eds research abstract book

RESEARCH ABSTRACT BOOK

VOLUME: 47 UPDATED: May 2009

Essential Dental Systems 89 Leuning Street

South Hackensack, NJ 07606 tel: 201.487.9090

fax: 201.487.5120 website: www.edsdental.com e-mail: [email protected]

TABLE OF CONTENTS VOLUME 47, May 2009

1 - Flexi-Post® and Flexi-Flange® Flexi-Post® and Flexi-Flange® Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ……… 1/1 Flexi-Post® and Flexi-Flange® Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . …… 1/1-1/47 2 - Flexi-Overdenture®, EDS’ AccessPost™ Overdenture, EZ-Change® Overdenture Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2/1 Overdenture Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ….. 2/1-2/5 3 - Ti-Core® Titanium and Lanthanide Reinforced Composite Core Materials Flexi-Flow Cem® Titanium and Lanthanide Reinforced Composite Cements Ti-Core® and Flexi-Flow Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . …. 3/1 Ti-Core® and Flexi-Flow Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . …. 3/1-3/45 4 - EDS’ AccessPost™ EDS’ AccessPost™ Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4/1 EDS’ AccessPost™ Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ……… 4/1-4/14 5 - SafeSiders® & EZ-Fill® SafeSiders® and EZ-Fill® Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5/1 SafeSiders® and EZ-Fill® Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . … 5/1-5/23 6- Glove'n Care® and Scrub’n Glove® Glove'n Care® and Scrub’n Glove® Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6/1 Glove'n Care® and Scrub’n Glove® Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6/1-6/3 7 – PulpOut Bur® PulpOut Bur® Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . …… 7/1 PulpOut Bur® Abstracts . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ……. 7/1-7/2 8- Irrigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ………………… 8/1-8/6 9 - General Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ………… 9/1-9/8 ______________________________________________________________________________ Essential Dental Systems, Inc. 89 Leuning Street, S. Hackensack, NJ 07606 USA Toll-free: 1-800-22-FLEXI Tel: 201-487-9090 Fax: 201-487-5120 E-Mail: [email protected]

FLEXI-POST® AND FLEXI-FLANGE® 1/1

FLEXI-POST® & FLEXI-FLANGE® Flexi-Post and Flexi-Flange was developed to solve the age-old problem of fracture potential, resulting from high stress during post insertion. Flexi-Post and Flexi-Flange are prefabricated, split-shank, parallel-sided, threaded posts that absorbs the stresses of insertion (by gradually closing during placement), while providing maximum retention. They are the essential posts for safety and retention. The Flexi-Flange system is a triple tier system that results in maximum coronal adaptation by incorporation of the flange. Musikant BL, Deutsch AS: A new prefabricated post and core system. J Prosthet Dent 1984;52:631-634. The Flexi-Post (which is an active parallel post, with blade-like threads and a second tier), is described as having tremendous retention for the post in the root, while minimizing the stress of insertion. With the use of photoelastic blocks observed through polarized light, the Flexi-Post had minimal stress during insertion. This included normal clinical torque of 3 to 4 inch.oz., resulting in no stress fringes, and insertion with a force of 40 inch.oz., resulting in minimal stress equally distributed over the length of the post. The Flexi-Post system, therefore, provides a design for reduced stresses of insertion and increased retention. Clinical Research Associates Newsletter, Prefabricated Posts. 1984;8:3. The Flexi-Post system has a unique, threaded, vertical split-shank design that allows extremely high post retention with minimal stress production on the tooth. Advantages include: 1) split-shank, which reduces stress in tooth during insertion, 2) very sharp threads in shank which are 1 mm apart and extend 0.2 mm from shank into dentin (allowing for excellent resistance to dislodgment from canal hole), 3) color coding, which allows for rapid identification, 4) tapered and non-threaded apical end of post, which facilitates penetration of tooth canal, and 5) a "second tier" (shank near coronal extension which is wider in diameter than apical shank), providing a stronger post and allowing positive seating.CRA evaluators found the product fast and easy to use. Deutsch AS, Musikant BL, Cavallari J. Effective post-hole Preparation for prefabricated posts. Quintessence International 1984;2:171-175. A safe, accurate method of post-hole preparation (1) uses non-end cutting reamers to achieve 100 percent of the length and 90 percent of the width of the post-hole and (2) limits insertion of the matched reamer

from the post system to as few times as possible in order to maintain maximum concentricity. Clinical Research Associates Newsletter, Flexi-Post Modified and Improved. 1985;9:12. The Flexi-Post is a screw-type post for endodontically treated teeth. It contains a unique stress-absorbing split in the apical portion of the shank, allowing relatively stress-free seating in previously cut post hole. A recent improvement is the internal wrench, which is used to decrease removal of coronal dentin and allow for post clearance during seating. Deutsch AS, Musikant BL, Antenucci G, Giusti P: Adaptation of a Prefabricated Post to Dentin. J Prosthet Dent 1985;53:182-184. An imaginative post design with a split up two-thirds of the shaft to absorb the stresses of insertion into a root has been introduced: Flexi-Post. Here, twenty single-rooted teeth with Flexi-Posts were sectioned longitudinally and examined. The following was observed: 1) The split shank displaced inwardly. 2) The self-tapping action of the threads was gradual. 3) The post (including the split) was completely enclosed in the cementing medium. 4) Only the threads engaged the root, while the second tier was definite stop for post placement. 5) The shaft of the post and the second tier were consistently separated from the root canal walls by approximately 0.1 mm of cement, with the threads engaged into the dentin. Musikant BL, Deutsch AS, Endodontics Posts and Cores, Part Two - Design of the Flexi-Post. J Alabama Dent. 1985;69:42-46. A newly designed threaded, split-shank, double-tiered, parallel endodontic post (Flexi-Post) is described to satisfy most endodontic criteria. This post combines maximum retention with minimum stress. The split-shank also allows space for dentinal debris to collect while eliminating most stresses of insertion. The intimate fit of the second tier reduces the stress of function to a minimum. Finally, the legs of the Flexi-Post collapse slightly during initial insertion to produce a taper of less than one degree. This results in maximum retention and minimal stress. Deutsch AS, Musikant BL The Flexi-Post as a Tap-In Post Placement. General Dentistry. 1986;146-147. Research from various clinicians indicates that parallel-threaded posts are the most retentive. The Flexi-Post, however, has a split-shank, permitting flexibility to tap the post before placement in the root canal. One reason the post fits so easily during tapping is that the dentinal debris generated is clogged or held up between the split. This reduces the torque of insertion. Therefore, instead of


clogging the spaces between the post and post hole, the Flexi-Post design results in minimum production of lateral stress with maximum retention of the post in the root. Millstein PL, Yu H, Hsu CS, Nathanson D. Effects of Cementing on Retention of a Prefabricated Screw Post. J Prosthet Dent 1987;57:171-174. This study evaluated the retention of the Flexi-Post with several dental cements. Three composite cements, Compspan (L.D. Caulk Co.), crown cementation paste (Den-Mat Corp.) and Flexi-Flow Cem Composite cement (Essential Dental Systems) were tested using zinc phosphate cement as the control. The zinc phosphate cement produced the highest mean separation forces (260 pounds), while the retentive strengths generated by different resin cements (Bis-GMA type) produced statistically similar results. Lentulo drills for spinning the cement into prepared canals significantly improved retention of the three resin cements. And zinc phosphate provided optimal retention. Brown JD. Retentive Properties of Dowel Post Systems. Oper Dent 1987;12:15-19. The retentive strength of several combinations of posts with cementing agents and canal treatments was determined using extracted human teeth. Many researchers have concluded that threaded and parallel-sided posts are most retentive. Here, the Flexi-Post system displayed twice the retention of the other systems evaluated, with retention of 260.1 pounds (+ 34.3) and 270.2 pounds (+ 43.4). It was cemented with Essential Dental Systems' composite cement (Flexi-Flow Cem) and glass-ionomer cement (Ketac-Cem), respectively. The Brasseler system, which used glass-ionomer cement at 111.9 pounds (+ 15.4), was statistically equal to the Whaledent Para-Post, also cemented with glass-ionomer cement at 106.1 pounds (+ 13.2). J.D. Brown believes that the "microthreads" on the Brasseler post have little influence on its retentive ability. Saunders RD, Lorey RE, Powers JM, Sloan KM, University of Michigan, Ann Arbor Michigan, A Comparison of Five Post-Cement Systems for Tensile Retentive Capacity. J Den Res 1988;67: IADR Abstract 304. The objective of this study was to compare and rate 5 groups of post cementation systems. Each groups consisted of 19 lateral incisor teeth with posts (approx. 0.07 inch diameter) cemented to a depth of 10 mm. Group 1 consisted of prefabricated stainless steel Para-Post cemented with zinc phosphate cement (Hy-Bond). Group 2 consisted of cast metal (Litecast B) smooth posts, cemented into post spaces for smear layer

removal (3% ferrite chloride, 10% citric acid), with a 4-Meta monomer resin cement (Super-Bond C & B). Group 3 consisted of serrated posts cast and cemented as in group 2. Group 4 consisted of tapered size 140 Endowels cast and cemented as in Group 2. Group 5 consisted of #2 Flexi-Post screw posts, cemented with Flexi-Flow composite cement. All groups were subjected to statistical analysis. The sample roots, with cemented posts, were embedded into acrylic resin, and tested on an Instron machine for tensile retention failure at a crosshead speed of 0.05 cm/min. Smooth posts (Group 2) were significantly more retentive than post in Group 1, 3, and 4. Cast serrated posts (Group 5) were as retentive as conventional prefabricated serrated stainless steel Para-Post (Group 1). Cast smooth tapered posts (Group 4) were the least retentive of all posts tested. Flexi-Posts (Group 5) were significantly more retentive than any other group tested. Sultan P. Ancranges Radiculaires. Du NOUVEAU. L'Incisive. 1989;47:6-7. Two principal groups of endodontic posts are described: passive posts (metal posts, with either smooth or matte surfaces, containing various shapes such as cylindrical or conical) and active posts (threaded, self-tapping, screw posts). Retention depends upon shape and length of post, with threaded posts being the most retentive. A new post design (Flexi-Post) is introduced. It has a split approximately two-thirds the length of the shank, to collect debris during tapping and reduce stress upon insertion. It also has a second tier to create an intimate contact between the post and most coronal portion of the root. Studies by numerous investigations have also shown that cementation of Flexi-Post increased its retention. Cementation with glass ionomer cement (Ketac Cem) results in the greatest retentive strength, with a value close to 140 Kg. Pettini PL, Salamanna S, Galantucci L, Simeone G, Crin Coli V. Valutazione Comparativa della Capacita ritentive di alcuni perni endocanalari. Minerva Stomatologica. 1989;38:1313-7. The retention of endodontic posts was evaluated in terms of post design, post diameter and cement employed. The following commercial products were examined: Flexi-Post (Essential Dental Systems), Para-Post Plus (Whaledent), Dentatus posts (Dentatus) with phosphacap (Vivadent), and Bondalap (Vivadent) cements. Greenfeld RS, Roydhouse RH, Marshall FJ, Schoner B. A comparison of two post system under applied compressive shear loads. J Prosthet Dent 1989;61:17-24.


This study tested the effects of compressive-shear loads applied to a human tooth restored with a composite crown supported by either a screw-type post (Flexi-Post) or a parallel, serrated type post (Para-Post. Ultimate failure was determined by crown alterations, post dislodgment and/or root fracture. Teeth restored with the Flexi-Post system did not fracture as frequently as those restored with the Para-Post system. Two failure modes, initial failure and ultimate failure, were evaluated for each system. The results clearly indicate that the Flexi-Post compared favorably with the Para-Post system and would facilitate endodontic treatment. Midwest Dental evaluation Group (MDEG). Flexi-Post Prefabricated Endodontic Post System. Interface. May/June 1989;1:3. Evaluations of the Flexi-Post system were unanimous concerning the quality of the Flexi-Post system. Evaluators recorded infrequent breakage of placement drills, very acceptable fit, and tolerances for related instruments. Smaller insertional forces were noted in comparison to self-threading systems, due to the split-shank design. Midwest Dental Evaluation Group (MDEG) found Flexi-Post to be a very high quality product and satisfying all requirements for a prefabricated post system, with few drawbacks. Boyarsky HP, Davis RD, Burgess, BO. Dentin-Retained Posts: An in vitro evaluation of root fracture. J Dent Res 1990;69 Abstract 122. Flexi-Posts were inserted into twenty teeth, while twenty control teeth had no posts inserted. All teeth were immersed in oil-red-o stain for five days, removed, and sectioned at four levels. These levels were: 1) one-half way between the end of the post and the apex, 2) at the end of the post, 3) at mid-post length, and 4) 1.0 mm between the CEJ. The sections were examined under a steromicroscope at 10 X power. The results suggest the Flexi-Post placement is no more stressful to a root than conventional endodontic therapy. Rosenberg SW. Chronic Dental Complications. NCI Monographs. 1990;9:173-178. Since the advent of radiation therapy (RI), and chemotherapy, long term survival rate of patients with certain cancers has increased. As a result, a new era of dental investigation, including treatment of chronic or delayed oral complications, has developed. The Flexi-Post system, which was designed to reduce root fracture, has become widely accepted in a variety of applications for endodontically treated teeth in irradiated patients. Under masticatory function, the Flexi-Post has been shown to cause fewer fractures of root than even a passive post, like

Para-Post. The Flexi-Post is, therefore, recommended when the danger of root fracture is critical. Wilson N, Hopwood WA. A clinical assessment of a split shank post system in permanent molar and premolar teeth. Quintessence International. 1990;21:907-11. This study assess the clinical use of a new split-shank post system in permanent molar and premolar teeth. Five investigators placed a total of 103 posts, and assessed the five operative procedures. A very high confidence level was obtained for the Flexi-Post system, because it proved to be a simple and effective technique in the restoration endodontically treated posterior teeth. University of Manchester Dental Hospital, Senior Operative Technique. 1990;37-39. The Flexi-Post system features a unique prefabricated post design aimed at reducing lateral insertional stress. This is achieved by the incorporation of a vertical split approximately two-thirds the length of the post shank. The post is parallel-sided, with sharp threads that tap the dentin during insertion. Advantages include: 1) a maximum of 1.0 mm thread penetration into dentin, 2) dentinal debris is directed into the vertical split, permitting apical placement of the post (without interference from the debris), 3) vented design enhances post cementation, and 4) the post compresses itself at the apical end where the root is fragile. Cohen BI, Musikant BL, Deutsch AS. Comparison of retentive properties of four post system. J Prosthet Dent. 1992;68:264-8. Retention of various diameter posts in root were studied: 0.05 inch/1.30 mm and 0.06 inch/1.60 mm posts from Unity, Filpost, and Brasseler were compared to the previously reported No. 1 and No. 2 Flexi-Posts. The retention of (0.05 inch/1.30 mm) posts, from most to least retentive, was: Flexi-Post No. 1 (zinc phosphate) (174.12 pounds) >Filpost (zinc phosphate) (81.20 pounds) >Filpost (resin) (70.60 pounds) >Brasseler (zinc phoshpate) (64.40 pounds) >Unity (resin) (60.50 pounds). The retention of (0.06 inch/1.60 mm) posts, from most to least retentive, was: Flexi-Post No. 2 (zinc phosphate) 265.89 pounds) >Filpost (zinc phosphate) (131.0 pounds) > Brasseler (zinc phosphate) (74.20 pounds) > Unity (resin) (64.20 pounds) > Filpost (resin) (63.40 pounds). Post retention of systems using resin cement with threaded canal walls falls far short of the retention achieved by the cemented threaded Flexi-Post. Burgess JB, Summitt JW, Robbins JW, Cronin JR, (UTHSC & Wilford Hall Med. Ctr., San


Antonio, TX), Four endodontic posts tested in tension, torsion and compression. J Dent Res 1991;Abstract 389:70. This study examined the forces required to displace four different endodontic posts (cemented with resin cement), when tensile, torsion, and compressive forces are applied. The coronal portion of 120 extracted mandibular premolars was removed at the CEJ. The teeth were divided into 12 groups of similar size. The pulpal tissue was removed. The canals were enlarged and irrigated with sodium hypochlorite. They were then dried and filled with gutta percha and Proco-Sol. Post preparations were made, using the recommended drills, to a depth of 9 mm. Posts with a standard length of 13 mm were cemented with one of two resin luting agents. Composite resin cores, fabricated around the coronal 4 mm of the posts and 2 threaded pins, were loaded in compression at 45o. The posts were aligned parallel to a paralleling device and the roots mounted in a metal cylinder with orthodontic resin. The specimens were placed into standardized fixtures and a constant load applied with an Instron. Each set of data was analyzed with an ANOVA and a multiple range test. Groups that are not statistically different are annotated with similar symbols. The Flexi-Post resisted tensile and torsion loads better than the other posts. Post & Luting Agent Tension Torsion Compression (Kg) (Kg/Cm) (Kg) Experimental Post & Resin 36.7 3.54 50.86 Parapost & Flexi-Flow 35.6 1.98 35.62 Vlock & Flexi-Flow 56.0 3.40 68.28 Flexi-Post & Flexi-Flow 98.6 5.85 59.12 Pameijer CH, Grasso J, The University of Connecticut, School of Dental Medicine, Farmington, CT. In vitro retention of three self tapping post & core systems. J Dent Res 1991;70:IADR Abstract 389. One-visit post and core techniques rely on the use of prefabricated posts, which are cemented in the prepared post space. The design of these posts would be such that they provide maximum retention, while exerting a minimum amount of stress on the remaining root structure. This study deals with the retentive values of three, threaded self-tapping systems only. The roots of extracted teeth were prepared to received posts from the following three systems. 1: Cytco (Caulk/Mailefer). 2: Flexi-Post (EDS). 3:Vlock

(Brasseler). The depth of the post space was 9 mm. A medium size drill and post was used for each system. All posts were cemented with zinc phosphate cement. The roots were imbedded in resin and retained in a copper cylinder, with an eyescrew at the end. (This was done to allow mounting and centering in an Instron machine). Fifteen samples were prepared for each group. The posts were pulled until separation or breakage of the root occurred. The following values were recorded: Cytco, 33Kg + 7.78. Flexi-Post, 54 + 12.63. And Vlock, 41.07 + 9.14. Statistical analysis (ANOVA) showed a significant difference between Cytco VS. Flexi-Post and Flexi-Post vs. Vlock (significant at 95%). No statistical difference was found for the Cytco vs. Vlock posts. In conclusion, retention required clinically is unknown. Therefore, an ideal system should only be selected after stress analysis for the three systems has been conducted, as reliance on retention alone is inappropriate. Musikant BL, Cohen BI, Deutsch AS. Retentive properties of Flexi-Post and three prefabricated post systems. J Dent Res 1991;70 IADR Abstract 2378:563. The purpose of this study was to compare the retention of three prefabricated post systems (Unity, Filpost, and Basseler) in the root (for various diameters, 0.05 inch/1.30 mm and 0.06 inch/1.6 mm) to that of the No. 1 (1.40 mm) and No. 2 (1.65 mm) Flexi-Post. The experiment was divided into three groups, comprising ten samples of each post system studied. In group 2, the Filpost system was cemented with both an unfilled resin and zinc phosphate cement. Retention values (measured in pounds) were obtained with a modified universal testing machine. The retention of (0.05 inch/1.3 mm) posts, from most to least retentive, was: Flexi-Post (zinc phosphate) 174 pounds> Filpost (zinc phosphate) 81 pounds> Filpost (resin) 71 pounds> Brasseler (zinc phosphate) 64 pounds > Unity (resin) 60 pounds. The retention of (0.06 inch/1.6 mm) posts, from most to least, was: Flexi-Post (zinc phosphate) 266 pounds> Filpost (zinc phosphate) 131 pounds> Brasseler (zinc phosphate) 74 pounds Unity (resin) 64 pounds> Filpost (resin) 63 pounds. The Filpost system achieves higher retention with zinc phosphate cement than it does with unfilled resin cement. Both Flexi-Post sizes tested were more than twice as retentive as the highest value of any of the other posts tested. Ross RS, Nicholls JI, Harrington GW. A comparison of strains generated during placement of five endodontic posts. J Endodon 1991;17:450-456.


Five endodontic posts were tested for the amounts of strain generated during post placement, where a non-threaded post (Para-Post Plus) acted as the control. The other posts tested were: Flexi-Post, Vlock post, Kurer Fin Lock Anchor, and Radix Anchor. Results demonstrated that the Flexi-Post (split-shank design) and the Vlock post (micro-thread design) generated strains which were statistically equivalent to the Para-Post Plus control. The Kurer Fin lock anchor and the Radix Anchor had strains which were extremely high, with no statistical difference. But, the Flexi-Post (a threaded, split-shank post) exhibited strain equivalent to that of a passive, non-threaded post (Para-Post Plus) when placed in a canal. The Flexi-Post produced low insertional stress during placement, accompanied by maximum retention in a canal. Chalfin HE, Goldberger RS. Management of post-induced radicular fractures in the coronal one third. PP & A. 1991;5:33-35. This clinical case report describes failure of a cast post, which caused root fracture, limited to the coronal one-third of the root. The tooth was retained by placement of a Flexi-Post (No. 2) with Ketac-Cem (glass ionomer cement). A core was then constructed, and prepared. And a crown fabricated. After one full year, examination of the patient gave no indication that failure was eminent. Robert D, Avon SL (Ecole de medecine dentaire, Universite Laval, Quebec, Canada). Torque needed to place prefabricated threaded posts. J Dent Res 1992;71 Abstract 133. The present study was undertaken to measure the torque needed to place prefabricated threaded posts and to evaluate the cutting efficiency of their threads in an homogenous material. A continuous measure of the torque developed to insert six types of posts was obtained with a rotating device designed to mechanically place posts into canals, prepared in Plexiglas blocks according to manufacturers instructions. The rotating device was connected to an Instron Universal Testing Machine. Two diameters of each of the following posts were tested: Cytco (Caulk Dentsply), Flexi-Post (EDS), and Vlock (Brasseler) and four specimens per type were used. To minimize frictional resistance, a lubricant (Cool-tec) specifically designed for Plexiglas was placed in each channel before insertion of the posts. The obtained curves were digitized and the total areas (force X length = energy (joules) under the curves were calculated. The total volume of material removed by the threads was also calculated (mm3). Results are as follows: Cytco 90 Cytco 120 Flexi-Post 1 Flexi-Post 2 mm 3 0.47 mm3 0.86 mm3 0.62 mm30.65 J 0.21 J 0.43 J 0.36 J 0.37

Vlock 2 Vlock 3 mm3 0.46 mm3 0.31 J 0.35 J 0.46 The Vlock 3 post was found to be the least efficient post, requiring the highest energy for the smallest volume of material removed. Cheng W, Millstein P (Boston University Goldman School of Graduate Dentistry, Boston, MA, USA). Design of prefabricated post heads on various core materials. J Dent Res 1992;71 Abstract 135. Core post adaptation as it relates to core materials and post head configurations was studied. Three hundred sixty samples consisting of combinations of 3 prefabricated post system: Flexi-Post (EDS), Para-post and Unity (Coltene-Whaledent); 3 core materials, amalgam (Tytin, Kerr), composite (Core-Paste, DenMat) and titanium reinforced composite (Essential Dental Systems) and core materials of 1 and 3 mm core covering thicknesses were made. Compressive an tensile failure loads were measured, in the absence of crowns using the Instron test machine. The mean values of 10 samples of each combination were analyzed using ANOVA and Newman-Keuls tests. The compressive tests revealed no statistically significant interactions between the variables. The compressive failure loads were affected by each single factor. Flexi-Posts, a 3 mm core thickness and amalgam were respectively most resistant to compressive force (p=0.05). In the tensile tests statistical interactions between post types and core materials and between post types and core covering thickness were significant. For both Flexi-Post and Para-Post amalgam was most resistant whereas for Unity, composite was more suitable (p=0.05). A 1 mm core thickness was significantly (p=0.05) more resistant for Para-Post with all core materials but insignificant for Flexi-Post and Unity. Flexi-Posts, a 3 mm core thickness and amalgam were respectively most resistant to compressive forces (p=0.05). Boyarsky H, DDS, Davis R, DDS. Root fracture with Dentin-Retained posts. American Journal of Dentistry. 1992;5:11-14. The purpose of this in vitro study was to compare the incidence of incomplete root fractures occurring in teeth with and without dentin-retained posts. Eighty extracted human mandibular canines were treated as follows: 20 teeth (controls) received pulpectomies using broaches and sodium hypochlorite; 60 teeth received endodontic therapy with laterally condensed gutta percha. Of those 60 teeth, 20 teeth received Flexi-Posts, 20 received Vlock dentin-retained posts, and 20 teeth had no posts placed. All teeth were stained with 5% Oil-Red-O stain for 5 days and


sectioned at four levels. The sections were then examined under a steromicroscope at X 20 power. No complete fractures were found. Incomplete fractures were found in two teeth from the endodontic treatment only group, two teeth from the Flexi-Post group, and two teeth from the Vlock group. None of the teeth in the control group were fractured. Based upon these results, it was concluded that Flexi-Post and Vlock post placement is no more likely to cause root fracture than is conventional endodontic therapy alone. The authors concluded that the following is of clinical significance: Occasionally, an active post is indicated for the restoration of an endodontically treated tooth. When the manufacturer's recommended techniques are followed, either the Flexi-Post or the Vlock dentin-retained post may be placed without significantly increasing the risk of root fracture. Musikant BL, Cohen BI, Condos S, Deutsch AS, (Essential Dental Laboratories, S. Hackensack,NJ). Flexi-Post retention with a titanium reinforced composite cement. J Dent Res 1992;72 Abstract 198. The purpose of this study was to compare the retention of various size Flexi-Posts (Nos. 00, 0, 1, and 2) in roots for two different cementation agents (Fleck's, zinc phosphate cement (ZOP) and Flexi-Flow Cem with titanium (FF Cem/ti)). The experiment was divided into eight groups which contained ten samples each. Retention values (measured in pounds) were obtained with a universal testing machine. ANOVA two-way analysis of variance (p<0.0001) and the Newman-Keuls multiple comparisons test were performed to determine which posts differed from each other. Values for retention with ZOP were: No. 00 (117.9), No. 0 (122.1) <No. 1 (174.1) <No. 2 (265.9 pounds). Values for retention with FF Cem/ti were: No. 00 (124.2), No. 0 (134.6) < No. 1 (208.5) <No. 2 (336.4 pounds). Within both the FF Cem and ZOP groups, Flexi-Post Nos. 00 and 0 are similar, but are different from Flexi-Post Nos. 1 and 2, which are different from one another. Comparing retention between cementation groups studied found that Flexi-Post Nos. 00 and 0 do not differ on mean load, but Flexi-Post Nos. 1 and 2 for the FF Cem/ti groups are statistically higher than the ZOP groups. The statistical increase in retention for the larger size Flexi-Post (Nos. 1 and 2) is probably due to deeper channels created by the threads of the post in the dentin and the higher cohesive strength for the titanium reinforced composite (Flexi-Flow Cem with titanium) as compared to the zinc phosphate cement. Cohen BI, Condos S, Musikant BL, Deutsch AS, (Essential Dental Laboratories, S. Hackensack, NJ). Cold treatment of stainless steel and

titanium alloy Flexi-Posts. J Dent Res 1992;72 Abstract 199. The purpose of this study was to determine if cold treatment at -96oC (using a sub-zero temperature freezer) affected the physical properties of different compositions and sizes of Flexi-Post. The experiment was divided into six separate groups. Two control groups were untreated stainless steel (50 posts) and titanium alloy (40 posts). The four experimental groups were: 1 time (1 X) and 2 times (2 X) cold treatment of 100 stainless steel and 80 titanium alloy posts. Each post was placed face-up in acrylic resin blocks and subjected to a force at a 26 degree angle, until the post heads broke. The breaking force test data (measured in pounds) was obtained with a universal testing machine. Values for breaking force for stainless steel (No. 00, 0, 1, 2 and 3) Flexi-Post were (N=10); control - 34.6, 38.9, 52.5, 77.1, 85.9 pounds; 1 X cold - 52.1, 65.0, 98.6, 90.4, 123.7 pounds and 2 X cold - 51.9, 70.4, 92.7, 85.3, 102.4 pounds. values for breaking force for titanium alloy (No. 00, 0, 2, and 3) Flexi-Posts were (N=10); control - 37.3, 44.3, 103.2 pounds; 1 X cold- 37.6, 36.2, 91.4, 88.9 pounds and 2 X cold- 34.7, 30.3, 63.9, 74.5 pounds. A two analysis of variance (ANOVA) (p<0.05) and a Newman-Keuls multiple range comparison test was used to determine which condition (control, 1 X and 2 X) differed from one another. Stainless steel Flexi-Posts all showed a significant increase in strength due to 1 X 2 X cold treatment. Titanium posts, however, showed no increase due to a single cold treatment, while they were weakened by a double cold treatment. Hence, we conclude that chemical composition differences between stainless steel and titanium alloy are affected by the cold treatment process. Burgess JO, Summit JB, Robbins JW. The resistance to tensile, compression and torsional forces provided by four post systems. J Prosthet Dent 1992;68:899-903. This study measured the force required to displace four different endodontic posts (an experimental, Para-Post, Flexi-Post, and Vlock) when tensile, torsion, or compressive forces were applied. Extracted mandibular premolars were decoronated at the cementoenamel junction, the roots were divided into groups of similar size, and the pulpal tissue was removed. The canals were enlarged, cleaned, and filled with gutta percha. Post preparations were made, and the posts were cut and cemented into the post spaces with resin cement. The roots were notched with a separating disc and lowered into a metal tube filled with acrylic resin. Two Minim pins were placed into the coronal dentin paralleling the post. Composite resin cores were made around the coronal 4 mm of the posts and the two pins for 10 specimens from each group. The specimens were placed into a standardized fixture and a load applied


until failure. The tensile load required to pull the experimental post and resin was significantly less than the load required to remove the threaded posts. Flexi-Posts provided the greatest resistance to torsion and tensile loading. The compressive load required to fracture the core over the post was significantly greater than the other post systems. The experimental post system tested, with its resin adhesive, polyacrylic acid conditioner, and drying agent did not provide a significant improvement over posts cemented with a conventional nonadhesive resin cement. Failure in almost all instances occurred at the dentin-resin interface; that is, failure was primarily adhesive at the dentinal surface. Because failures occurred at the cement-dentin interface, it is not surprising that the tensile values for nonthreaded post systems were similar. Threaded post systems provided significantly higher tensile resistance than the cemented post systems. Burns, DR, Douglas HB, Moon Pc. Comparison of the Retention of Endodontics Posts after preparation with EDTA. J Prosthet Dent 1993;69:262-6. Significant differences in the retention of performed endodontic posts for endodontically treated teeth were determined with (1) parallel sided, passively placed Para-Post dowel versus mechanically engaging, threaded Flexi-Post dowel; (2) irrigation of canals with EDTA; (3) cementation with urethane dimethacrylate resinous or zinc phosphate cement. It was hypothesized that EDTA would substantially increase retention by removing the smear layer on the prepared canal wall and create micromechanical retention in the dentin. Extracted teeth were prepared with endodontic posts and divided in groups representing combinations of variables. The forces for post removal and the locations of the retentive bond failures were recorded. The results indicated that EDTA did not significantly affect retention. The Flexi-Post dowel was significantly more retentive than the Para-Post dowel but also exhibited a greater potential for tooth damage compared with the Para-Post dowel during retentive failure loads. 1. EDTA treatment for the removal of the smear layer in a root canal before endodontic post cementation is potentially harmful. 2. If an appropriately positioned endodontic post is loaded with a sufficient shear force for retentive failure of the post, the Flexi-Post dowel possesses more potential for irreversible tooth failure than the Para-Post dowel. 3. The force necessary for retentive failure of the Flexi-Post dowel was substantially greater than that required for the Para-Post dowel. Cohen BI, Condos S, Musikant BL, Deutsch AS. Retentive properties of threaded split-shaft posts

with titanium-reinforced composite cement. J Prosthet Dent 1992;68:910-2. The retention of posts in tooth roots is vital to the success of the restoration. This study compared the retention of posts of various sizes and diameters cemented with a titanium-reinforced composite cement with that of posts previously reported cemented with zinc phosphate cement. Four groups made up of 10 samples each were used and retention values were compared using a universal testing machine. Two-way analysis of variance and the Newman-Keuls multiple range comparison tests were performed. Larger diameter posts cemented with titanium cement had better retention than similar posts cemented with zinc phosphate cement. The statistical in retention for larger size posts is probably the result of the deeper channels (threads) in the dentin and the higher cohesive strength for the titanium-reinforced composite resin. 1. Within both the titanium cement and zinc phosphate cement controls Flexi-Post posts Nos. 00 and 0 are similar in retention, but differ from the retention values of Flexi-Post dowels Nos. 1 and 2, which are different from one another. 2. Comparison between cementation groups studied found that Flexi-Post dowels Nos. 00 and 0 do not differ in retention, but Flexi-Post dowels Nos. 1 and 2 for the titanium cement groups are statistically higher in retention than the zinc phosphate cemented controls. 3. The statistical increase in retention for the larger size Flexi-Post dowels (Nos. 1 and 2) cemented with Flexi-Flow titanium cement is probably a result of the deeper channels created by the threads of the post in the dentin and the higher cohesive strength for Flexi-Flow cement with titanium compared with zinc phosphate cement. Cohen BI, Condos S, Musikant BL, Deutsch AS. Retention properties of a split-shaft threaded post: Cut at different apical lengths. J Prosthet Dent 1992;68:894-8. The retention of the post to the root of an endodontically treated tooth is critical for a successful restoration. Modification of the post length to accommodate a specific clinical situation is common. This study compared the retention of No. 1 and No. 2 Flexi-Post restorations shortened apically form 1 to 5 mm with that reported for full-length control No. 1 and No. 2 Flexi-Post dowels. The experimental material was divided into 10 groups with 10 samples in each group. Retentive values were recorded in pounds with a universal testing machine. Analysis of variance with a Tukey-Student range, multiple comparison test showed no statistical differences from apical reductions of 1, 2, 3, and 5 mm including the full-length control Flexi-Post No. 1 system. With 4 mm of apical shortening statistically greater retention was recorded. No statistical


differences resulted with apical reductions of 1 to 4 mm or with the full-length control Flexi-Post No. 2 system, but 5 mm of apical shortening caused significantly less retention. 1. There was no significant difference in retention of Flexi-Post No. 1 dowels between the control group and the groups shortened by 1, 2, 3, or 5 mm. 2. The No. 1 Flexi-Post system recorded a statistically significant increase (p<0.011) in retention for posts reduced by 4 mm. 3. There was no significant difference in retention for the Flexi-Post No. 2 system between the full-length control group and the groups shortened by 1, 2, 3, or 4 mm. 4. A statistically significant (p<0.001) difference in retention was observed for the Flexi-Post No. 2 dowel shortened by 5 mm and the remaining groups: The full-length control and 1, 2, 3, or 4 mm apical reductions. 5. Reducing the post shaft length to 4 mm for both the Flexi-Post No. 1 and No.2 dowels did not adversely affect the retention of the post. Milot P, Stein RS. Root fracture in endodontically treated teeth related to post selection and crown design. J Prosthet Dent 1992;68:428-35. Standardized plastic analogues simulating an endodontically treated maxillary central incisor root were used to investigate the resistance to root fracture in endodontically treated teeth. Three different post and core systems were used: (1) cast post and core, (2) Para-Post Plus post and (3) Flexi-Post post. The core build-up material selected in this study was Ketac Silver material, after which a crown preparation was made on each analogue. Two types of preparations were used: a wide chamfer margin (butt-joint) and a wide chamfer margin with a 1.00 mm circumferential bevel. An overcasting was fabricated and was permanently cemented on each preparation. Assemblies were subjected to an increasing lingual oblique force until fracture occurred. Results were tabulated using the analysis of variance (F test) and Student's test. Beveled preparations with a concomitant final restoration provided a significant increased resistance to root fracture. Furthermore, vertical fracture occurred twice as often with nonbeveled preparations. 1. When most of the tooth structure is preserved, the post selection has little or no effect on resistance to root fracture. 2. A beveled preparation with the concomitant final restoration offers an increased resistance to root fracture. 3. A nonbeveled preparation with a concomitant final restoration is more prone to an incidence of vertical fractures.

Cohen BI, Deutsch AS, Musikant BL. Cyclic fatigue testing of six endodontic post systems. J Prosthod. 1993;2:28-32. In a new experimental approach, in vivo biting force was compared with in vitro dynamic instantaneous forces delivered by a fatigue testing machine. Six prefabricated post systems were studied. The maximum average anterior in vivo biting force of 60 lb was found to be in the same range as an instantaneous applied force of 5.0 lbs. All samples for Flexi-Flange, Flexi-Post, Parapost, and EDS’ AccessPost showed no failure after 2,000,000 repetitions. Sixty percent of Vlock and all the Cytco post systems failed before the completion of the test configuration (failed before 2,000,000 cycles). It is believed that this experimental setup comes closer to simulating the biting forces seen clinically than does static loading applied to a test sample. Cohen BI, Musikant BL, Deutsch AS. Comparison of the photoelastic stress for a split-shank threaded post versus a threaded post. J Prosthod 1994;3:53-55. This study compared the stress distribution during insertion and after cementation for two prefabricated endodontic posts, (1) a split-shank threaded post, and (2) a threaded post with no split in the shank. Three test blocks of photoelastic material were prepared with simulated endodontic canals for each group studied. Specimens were then photographed after insertion and cementation. Minimal stresses were observed for the post with a split (group 1) throughout the length of the shaft, whereas asymmetric patterns of stresses for the post without a split (group 2) were present. Stress distribution for the post without a split were concentrated more apically rather than coronally. The presence of a split reduces insertion and cementation stresses for this post system. The split also acts as a vent during the cementation of the post into the canal and minimizes stress concentration during cementation. Cohen BI, Condos S, Musikant BL, Deutsch AS. Retentive properties of Flexi-Post cut at different apical lengths. J Dent Res 1994;73 Abstract 1790:325. Alteration of the post length to accommodate a particular clinical situation is common. Further, when it is necessary to shorten the Flexi-Post, the apical end must be cut in order to fully seat the second tier. This study compared the retention of Nos. 1 and 2 Flexi-Post cut apically at different lengths from 1 mm to 5 mm to that of the previously reported full-length values (controls). The experiment was divided into ten groups comprising ten samples each. For all samples studied, single rooted human teeth were used. Retention values were recorded in pounds with the use of a universal testing machine. ANOVA (one-way analysis of


variance) (p<0.001) with Tukey's studentized range multiple comparison test was obtained. Values for apical cutting for the No. 1 Flexi-Post were (pounds): 1 mm (183.5 + 22.4), 2 mm, (162.8 + 22.2) 3 mm (152.4 + 31.9), 4 mm (190.3 + 40.0), 5 mm (149.5 + 25.6) and full length control (174.1 +24.0). Values for apical cutting for No. 2 Flexi-Post were (pounds): 1 mm (299.2 + 96.3), 2 mm (282.2 + 52.5), 3 mm (296.9 + 51.0) 4 mm (235.4 + 58.6), 5 mm (180.5 + 49.7) and full length control (265.9 + 25.7). For the No. 1 Flexi-Post, no statistical decrease of retention results for apical cutting of 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm as compared to the full length control. For the No. 2 Flexi-Post, no statistical decrease of retention results from apical cutting of 1 mm, 2 mm, 3 mm, and 4 mm as compared to the full length control. 5 mm of apical cutting for the No. 2 Flexi-Post however, results in statistically smaller retention. These results demonstrate that apical reduction of approximately 40 % of the length of the Flexi-Post does not statistically reduce the retention for the post. Cohen BI, Condos S, Musikant BL, Deutsch AS. Pilot study comparing the photoelastic stress distribution for four endodontic post systems. Journal of Oral Rehabilitation 1996;23:679-685. This study compared the stress distribution under function using photelastic blocks for both vertical or compressive loading and oblique loading (on a 26 degree angle) for four post systems, groups 1-4 Flexi-Post, Flexi-Flange, Parapost and EDS’ AccessPost). Three test blocks of photoelastic material were prepared with simulated endodontic canals for each group studied. Specimens were then photographed. Minimal stresses were observed for all the posts studied after cementation in the unloaded state. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable under compressive loading at 30 pounds and stress patterns were symmetric over the entire length of the post. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable under oblique loadings of 20 and 30 pounds and stress patterns were symmetric over the entire length of the post. Stress distribution for the ParaPost under compressive loading at 30 pounds showed stress patterns which were asymmetric with concentration of stresses apically as compared to coronally. Stress distribution for the ParaPost under oblique loadings of 20 and 30 pounds were asymmetric with stress concentrated apically as compared to coronally. Cohen BI, Pagnillo M, Condos S, Deutsch AS, Musikant BL. Comparison of the torsional forces for seven endodontic post systems. J Prosthet Dent 1995;74:350-357. Increased resistance to torsional forces is an important factor in the restoration of the

endodontically treated tooth. In this study, seven different post designs (Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World Post, Vlock and Dentatus post) were cemented into tooth roots using two different post cements (Zinc phosphate and Flexi-Flow). This resulted in 11 different groupings which were subjected to torsional forces in the clockwise direction. In addition, two different directions were used (clockwise and counterclockwise) for the Flexi-Post and Flexi-Flange systems cemented with ZOP and Flexi-Flow. Torsional forces for the groups studied, ranged from 17 oz-inches (Dentatus/ZOP) to 81 oz-inches (Flexi-Post/ZOP). The threaded posts, Flexi-Post and Flexi-Flange resulted in the highest torsional forces obtained. As a result of torsional testing the heads were displaced from the posts. all other specimens from other groups resulted in removal of the posts (Parapost, EDS’ AccessPost, World Post, Vlock and Dentatus) from their corresponding root canals with no head displacement. Analysis were then carried out suing one-way and two-way analysis of variance (ANOVA), followed by Duncan's multiple range test. The only conclusive differences were between groups 11 (Dentatus/ZOP) and all other groups studied. Therefore, no conclusive differences in mean torque was observed for Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World post and Vlock post regardless of cement and direction of torque used. Musikant BL, Deutsch AS, Cohen BI. Presentation of a new Flexi-Flange post system for clinical use. Journal of Oral Rehabilitation 1995;22:435-437. Advantages of a new post design, Flexi-Flange, is described which incorporates a split shank parallel threaded post with a flange that seats into an occlusal countersunk dentin space. This case report describes placement of three Flexi-Flange posts in a first bicuspid, canine and central incisor. The Flexi-Flange system offers, high retention of the post in the root, superior distribution of stresses under insertion and under function, and long term resistance to metal fatigue. Cohen BI, Musikant BL, Deutsch AS. Retrospective review: A ten year literature review of a split-shank threaded post. Compend Contin Educ Dent 1995;16:630-631. A literature review of the last ten years is discussed for prefabricated threaded and passive post systems. A review of recent dental literature supporting the validity of the split-shanked thread post design, Flexi-Post is also discussed. It is important to be aware of the fact that a split-shanked post is altogether different from a solid-shanked threaded post. The research discussed confirms the high retention of the Flexi-Post and dispels the notion that high retention must be accompanied by high stress.


Cohen BI, Musikant BL, Deutsch AS. The Flexi-Flange post system and its clinical usage. Compend Contin Educ Dent 1994;15:1124-1128. The clinical case below, reports on the use of No. 2 Flexi-Flange posts to restore a first premolar and canine. The unique design of the Flexi-Flange includes a parallel threaded primary shank that is split along its longitudinal axis, a second tier for close adaptation of the post to the root at the point where coronal flares often exist and a wider third tier that fits within a machined root faced area. The result of a Flexi-Flange post is a post with a large metal to dentin interface without the need of a wide taper. The advantages of a tiered system over a tapered system include significantly less lateral stresses during insertion and function. The Flexi-Flange system offers; high retention of the post in the root, superior distribution of stresses under insertion and under function, and long term resistance to metal fatigue. Filiz K, Erdal S. Retentive properties of three post-core systems. Australian Dental Journal 1994;39:(1):20-24. The retention in root canals of Flexi-Posts, ParaPosts and Brasseler/Vlock Posts was measured using tensile and compressive/shear forces. Forty-two extracted maxillary anterior teeth were embedded in self-curing acrylic resin and treated endodontically. Each root canal was prepared with the appropriate matching drills for the post-core system chosen. Each post-core was cemented in the canal with zinc phosphate cement. A tensile force was applied along the long axis of each tooth and the force needed to dislodge the post-core was recorded. There was no difference in retention between the small diameter posts, but the difference between the medium and the large diameter posts, however, was significant. In the medium diameter post group, the Flexi-Post was approximately twice as retentive as the other two post-core systems evaluated. In the second series of tests compressive/shear force was applied at an angle of 130 degrees to the long axis of the tooth. The retention difference between the small diameter posts was found to be statistically significant, Flexi-Post being more retentive than ParaPost and B/V posts. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS. Comparison of the retentive and photoelastic properties for a split-shank threaded post versus a threaded post. J Esthet Dent 1995;7:174-178. This study compared the retentive and photoelastic properties of two active post systems. In addition, photoelastic stress distribution during insertion and after cementation for two prefabricated endodontic posts, 1) Flexi-Post (a split-shank threaded post) and 2) ParaPost XT (a threaded post) were also performed. Two groups making up 10 samples each

were used and retention values were compared using a universal testing machine. In addition, three test blocks of photoelastic material were prepared with simulated endodontic canals for each group studied. Specimens were then photographed after insertion and cementation. One-way analysis of variance was performed regarding the retentive properties. ANOVA revealed a highly significant difference (p<0.0001) between groups. Flexi-Post had a significantly higher retention than ParaPost XT. The Flexi-Post had a retention of 265.9 pounds, where the ParaPost XT had a retention of 137.7 pounds. Photoelastic results were; minimal stresses are observed for the Flexi-Post, while extreme asymmetric patterns of stresses for the ParaPost XT are present. Stress Distribution for the ParaPost XT are concentrated more coronally as compared to apically. The presence of a split for the Flexi-Post system reduces insertion and cementation stresses for this post system. The split also acts as a vent for release of hydrostatic pressure during cementation of the post into the canal and minimizes stresses during cementation. Cohen BI, Condos S, Musikant BL, Deutsch AS. Retentive properties of Flexi-Post cut at different apical lengths. Mosby Year Book of Restorative and General Dentistry July 1994 Chapter 12:326-328. When endodontic posts are shortened, fewer flexible threads are present at the apex than with the original, unaltered Flexi-Post dowel. The apical threads of the post then invade the dentin more deeply, and almost all threads fully engage dentin from the apex to the coronal surface of the root instead of the 3 to 4 levels of threads not engaging dentin near the apex in the unaltered post. Commentary by Berry, T.G. D.D.S.,M.A. The post and core restoration offers a very crucial means of restoring the badly broken-down tooth, but it is not without its problems. It is not always easy to achieve a post that is adapted to the canal along its entire length well enough to offer excellent retention without creating a wedging force. The Flexi-Post system offers a post that can create retention without undue internal pressures. Many of the posts (29%) must be shortened, so it is reassuring that shortening the post actually adapts it better to the canal walls. The remaining threads do cut into the dentin to gain excellent retention. For many situations, the Flexi-Post has proved to be an excellent choice for restoring the tooth. Cohen BI, Condos S, Deutsch AS, Musikant BL. Fracture strength for three different core materials in combination with three different endodontic posts. Int'l J Prosthod 1994;7:178-182.


The purpose for this study was to determine the fracture load for three different core materials supported by three different posts systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3x 3 factorial two-way analysis of variance (p<.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were: Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin 100.6; Parapost/Tytin, 134.6; Flexi-Post/Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and Parapost/Ketac-Silver, 37.7; The Titanium composite, Ti-Core, had the greatest fracture load values in all instances; the silver-filled glass-ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the Parapost had the least. Both the Flexi-Post and the Vlock post have large bulky heads with many vertical and horizontal grooves, apparently facilitating the locking of the core material into the post. Cohen BI, Condos S, Musikant BL, Deutsch AS. Proprieta` ritentiva del perno Flexi-Post tagliato a diverse lunghezze apicali. Minerva Ortognatodontica 1994;12:61-67. The retention of the post to the root of an endodontically treated tooth is critical for a successful restoration. Modification of the post length to accommodate a specific clinical situation is common. This study compared the retention of No. 1 and 2 Flexi-Post restorations shortened apically from 1 to 5 mm with that reported for full-length control No. 1 and No. 2 Flexi-Post dowels. The experimental material was divided into 10 groups with 10 samples in each group. Retentive values were recorded in pounds with a universal testing machine. Analysis of variance with a Tukey-Student range, multiple-comparison test showed no statistical differences from apical reductions of 1,2,3, and 5 mm including the full-length control Flexi-Post No. 1 system. With 4 mm of apical shortening statistically greater retention was recorded. No statistical differences resulted with apical reductions of 1 to 4 mm or with the full-length control Flexi-Post No. 2 system, but 5 mm of apical shortening caused significantly less retention. Cohen BI, Deutsch AS, Musikant BL. Prove cicliche di affaticamento di sei perni endodontici. Minerva Ortognatodontica 1994;12:229-235. This study tested the comparative cyclic fatigue of six prefabricated post systems (Flexi-Post (Essential Dental Systems, South Hackensack, NJ), Flexi-Flange (Essential Dental Systems), Vlock (Brasseler

USA, Inc. Savannah, GA), ParaPost (Whaledent/Coltene, New York, NY), Cytco (L.D. Caulk, Milford, DE), and EDS’ AccessPost (Essential Dental Systems). Cyclic fatigue testing was obtained with an in vitro fatigue machine that simulated clinical fatigue conditions. An instantaneous applied force of 5.0 pounds was applied to each post specimen and data was recorded when post breakages occurred. If no breakages occurred, then the test was stopped after 2,000,000 repetitions. Failures only occurred with the Cytco and Vlock post designs. The Flexi-Post, Flexi-Flange, ParaPost and the EDS’ AccessPost all had greater resistance to cyclic fatigue with no failures. This experimental design may simulate biting forces and stresses seen for posts in a clinical situation. Musikant BL, Cohen BI, Pagnillo M, Condos S, Deutsch AS. Retentive and Photoelastic Properties of Two Threaded Post Systems. J Dent Res 1995;74 Abstract 781:109. This study compared the retentive and photoelastic properties of two active post systems. In addition, photoelastic stress distribution during insertion and after cementation for two prefabricated endodontic posts, A) Flexi-Post (a split-shank threaded post), and B) ParaPost XT (a threaded post) were also performed. Two groups making up 10 samples each of single rooted human teeth (cemented with zinc phosphate) were used and retention values were compared using a MTS 810 materials testing machine. In addition, three test blocks of photoelastic material (PSM-5) were prepared with simulated endodontic canals for each group studied. Specimens were then photographed after insertion and cementation. One-way analysis of variance was performed regarding the retentive properties. ANOVA revealed a highly significant difference (p<0.0001) between groups. Flexi-Post had a significantly higher retention than ParaPost XT. The Flexi-Post had a retention of x=265.9 (SD=25.7) pounds, where the ParaPost XT had a retention of X=137.7 (SD=14.3) pounds. Photoelastic results were; minimal stresses were observed for the Flexi-Post, while extreme asymmetric patterns of stresses for the ParaPost XT were present. Stress distribution for the ParaPost XT are concentrated more coronally as compared to apically. The presence of a split for the Flexi-Post system reduces insertion and cementation stresses. The split also acts as a vent for release of hydrostatic pressure during insertion of the post into the canal and minimizes stresses during cementation. Cohen BI, Pagnillo M, Condos S, Musikant BL, Deutsch AS.


Comparison of seven endodontic post systems measured for torsion. J Dent Res 1995;74 Abstract 782:109. Increased resistance to torsional forces is critical in the restoration of the endodontically treated tooth. Seven different post designs (Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World Post, Vlock and Dentatus posts) were cemented into single rooted human teeth with zinc phosphate (ZOP) and Flexi-Flow (FF) with titanium cements. This resulted in 11 different groupings that were subjected to torsional forces using a torque transducer (Lebow Model No. 1102-200) in a clockwise direction. In addition, two different directions were used (clockwise and counter clockwise) for the Flexi-Post and Flexi-Flange systems. Torsional force values (oz-inch) were (N=10) clockwise; Flexi-Post/ZOP 76.57 (sd=12.23), Flexi-Post/ZOP/ Counterclock 81.75 (sd=17.73), Flexi-Post/FF 75.25 (sd=10.23), Flexi-Post/FF/Counterclock 68.88 (sd=13.39), Flexi-Flange/ZOP 62.00 (sd=10.54), Flexi-Flange/ZOP/Counterclock 68.00 (sd=18.19), Flexi-Flange/FF 55.57 (sd=10.97), Flexi-Flange/FF/ Counterclock 62.82 (sd=7.88), ParaPost/ZOP 51.94 (sd=16.99), EDS’ AccessPost/ZOP 51.81 (sd=15.28), EDS’ AccessPost/FF/ 37.00 (sd=7.05), World Post/ZOP 41.57 (sd=9.17), World Post/FF 39.89 (sd=6.64), Vlock/ZOP 43.69 (sd=8.11), and Dentatus/ZOP 17.56 (sd=5.83). Analysis were then computed with one-way and three-way analysis of variance (ANOVA), followed by Duncan's multiple range test. Duncan's multiple range test showed that Flexi-Post/ZOP/Clockwise was similar to Flexi-Post/FF/Clockwise and both had significantly higher torque levels than the other treatment conditions. Dentatus/ZOP/clockwise had significantly lower torque levels than the other treatment conditions. The threaded posts, Flexi-Post and Flexi-Flange resulted in statistical greater torsional forces as compared to other post systems studied. The Dental Advisor Plus. January/February 1995;5:1. Flexi-Flange ++++1/2 (Essential Dental Systems, Inc., 89 Leuning St., S. Hackensack, NJ) TDA PLUS Recommendation Flexi-Flange is highly recommended as a prefabricated, threaded post for restoration of endodontically treated teeth. It received a 91% approval rating. Description Flexi-Flange is a unique, parallel-sided, threaded post. The spiral end of the post is tapered and split midway up the shank. The split-shank design minimizes apical stresses upon insertion. The post has a triple-tiered design with a flange that seats into the prepared occlusal portion of the root. The posts

are available in 4 diameters, and the kit includes all the necessary components. Sixteen consultants evaluated Flexi-Flange. Positive Features Flexi-Flange is a well thought out, easy to use post system with an adequate size selection. The post space is easily prepared with the provided reamers and countersink drills. The countersink provides the post with a positive seat and helps reduce apical stress. The posts seated completely during trial insertion and cementation. Consultants felt that the split shank design would reduce apical root stresses. Selection of the proper post size is simplified by placing the depth gauge over an accurate radiograph. Most consultants stated that they would purchase or recommend Flexi-Flange. Consultants' Comments Cutting the post to length is best done with a carborundum disc. Establishing the countersink in some posterior teeth may be difficult because of the anatomy of the pulp chamber. Ratings Excellent +++++ Very Good ++++ Good +++ Fair ++ Poor + Cohen BI, Condos S, Deutsch AS, Musikant BL. Comparison of photoelastic stress properties for four prefabricated post systems. J Dent Res 1995;74 (IADR) Abstract 1254:557. This study compared stress distribution using photoelastic blocks for both vertical and oblique loading (at a 26 degree angle) for four prefabricated post systems, groups 1-4 (Flexi-Post, Flexi-Flange, Parapost and EDS’ AccessPost dowels). Three test blocks of photoelastic material (PSM-5, with a modulus of elasticity similar to dentin) were prepared with simulated endodontic canals for each group. Circular polarizer sheets were then placed on each block. Each post was cemented with zinc phosphate cement. Specimens were positioned in a special jig on a universal testing machine and then photographed in three test modes; unloaded, vertical at 30 pounds and obliquely at 20 and 30 pounds. Minimal stresses were observed for all the posts after cementation in the unloaded state. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable (symmetric) under vertical loading at 134 Newtons (30 pounds) and oblique loadings of 89 N (20 pounds) and 134 N (30 pounds). Stress patterns were symmetric over the entire length of these posts.


Stress distribution for the ParaPost under vertical loading at 134 N (30 pounds) generated stress patterns that were asymmetric with concentration of stresses apically compared to coronally. Stress distribution for the ParaPost during oblique loadings of 89 N (20 pounds) and 134 N (30 pounds) were also asymmetric with stress concentrated apically as compared to coronally. Greater "bottoming out" stresses were observed for the ParaPost system due to its single tiered design and lack of a second tier. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were all favorable (symmetric) under loading conditions studied. The Flexi-Post, Flexi-Flange and EDS’ AccessPost systems represent multi-tiered post designs. The ParaPost system however, resulted in unfavorable (asymmetric) stress distribution under similar loading conditions. This results from the single tiered ParaPost design. Cohen BI, Musikant BL, Deutsch AS. Clinical usage of the Flexi-Flange post system. Dental News 1995;Vol. II (III):33-36. The Flexi-Flange post offers the combination of the following; 1) safe high retention of the post in the root. 2) superior distribution of stresses under insertion and under function. and 3) long term resistance to metal fatigue. All of these attributes for the Flexi-Flange system equate to a stable final restoration. The unique design of the Flexi-Flange includes a parallel threaded primary shank that is split along its longitudinal axis, a second tier for close adaptation of the post to the root at the point where coronal flares often exist and a wider third tier that fits within a machined root faced area. Clinical experience suggests that the flange is most important where no coronal dentin exists to support the head of the post. Where coronal dentin exists. The forces acting on the core are largely reduced by the circumferential dentin. In fact, if enough dentin exists, there is no need for placement of a post. Condos S, Cohen BI, Musikant BL, Deutsch AS. The Effect of a Split-Shank Threaded Post on Photoelastic Stress. J Dent Res 1996;75 IADR Abstract 2931:384. This study compares the stress distribution during insertion and after cementation using photoelastic blocks for a split-shank threaded post, Flexi-Post (group 1) to that of a threaded Flexi-Post without a split in the shank (group 2). Photoelastic stress analysis concerns qualitative visual observations based on the ability of transparent plastic to exhibit interference fringes when stressed in a polarized light. Fringes that are observed represent zones of stress intensity or concentration and can be identified by a sequence of color bands. Colors observed for these bands can range from black (no stress), yellow, red, blue, etc. with the colors yellow, red and blue

representing a maximum stress pattern. Three stress free testing blocks of photoelastic material were prepared with simulated endodontic canals for each group studied. Specimens were then photographed after insertion and cementation. Minimal stresses was observed for the Flexi-Post with a split (group 1) throughout the length of the shaft, while asymmetric patterns of stresses for the Flexi-Post without a split (group 2) are present. Stress distribution for the Flexi-Post without a split are concentrated more apically as compared to coronally and additional stresses occurred during the tapping and cementation procedure for the Flexi-Post without a split. Therefore, the presence of a split for the Flexi-Post system clearly eliminates insertion and cementation stresses for this post system. The split also acts as a vent during the cementation of the post into the canal and minimizes stress concentration during cementation. Cohen BI, Deutsch AS, Musikant BL. Examen de la fatiga clinica de seis sistemas de espigas endodonticas. Rev. Asoc Odontol Argent 1995;83 (April/June):119-124. This study tested the comparative cyclic fatigue of six prefabricated post systems (Flexi-Post (Essential Dental Systems, South Hackensack, NJ), Flexi-Flange (Essential Dental Systems), Vlock (Brasseler USA, Inc. Savannah, GA), ParaPost (Whaledent/Coltene, New York, NY), Cytco (L.D. Caulk, Milford, DE), and EDS’ AccessPost (Essential Dental Systems). Cyclic fatigue testing was obtained with an in vitro fatigue machine that simulated clinical fatigue conditions. An instantaneous applied force of 5.0 pounds was applied to each post specimen and data was recorded when post breakages occurred. If no breakages occurred, then the test was stopped after 2,000,000 repetitions. Failures only occurred with the Cytco and Vlock post designs. The Flexi-Post, Flexi-Flange, ParaPost and the EDS AccessPost all had greater resistance to cyclic fatigue with no failures. This experimental design may simulate biting forces and stresses seen for posts in a clinical situation. Cohen BI, Condos S, Musikant BL, Deutsch AS. Propiedades retentivas de la espiga roscada de mango abierto: Cortada a diferentes distancias apicales. Soproden 1995;XI (3):265-270. The retention of the post to the root of an endodontically treated tooth is critical for a successful restoration. Modification of the post length to accommodate a specific clinical situation is common. This study compared the retention of No. 1 and No. 2 Flexi-Post restorations shortened apically form 1 to 5 mm with that reported for full-length control No. 1 and No. 2 Flexi-Post dowels. The experimental material was divided into 10 groups


with 10 samples in each group. Retentive values were recorded in pounds with a universal testing machine. Analysis of variance with a Tukey-Student range, multiple comparison test showed no statistical differences from apical reductions of 1, 2, 3, and 5 mm including the full-length control Flexi-Post No. 1 system. With 4 mm of apical shortening statistically greater retention was recorded. No statistical differences resulted with apical reductions of 1 to 4 mm or with the full-length control Flexi-Post No. 2 system, but 5 mm of apical shortening caused significantly less retention. 1. There was no significant difference in retention of Flexi-Post No. 1 dowels between the control group and the groups shortened by 1, 2, 3, or 5 mm. 2. The No. 1 Flexi-Post system recorded a statistically significant increase (p<0.011) in retention for posts reduced by 4 mm. 3. There was no significant difference in retention for the Flexi-Post No. 2 system between the full-length control group and the groups shortened by 1, 2, 3, or 4 mm. 4. A statistically significant (p<0.001) difference in retention was observed for the Flexi-Post No. 2 dowel shortened by 5 mm and the remaining groups: The full-length control and 1, 2, 3, or 4 mm apical reductions. 5. Reducing the post shaft length to 4 mm for both the Flexi-Post No. 1 and No.2 dowels did not adversely affect the retention of the post. Cohen BI, Condos S, Deutsch AS, Musikant BL. Fracture strength of three different core materials in combination with three different endodontic posts. Abstract citation in the Int Endod J 1996;29:51. The purpose for this study was to determine the fracture load for three different core materials supported by three different posts systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3 x 3 factorial two-way analysis of variance (p<.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were: Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin 100.6; Parapost/Tytin, 134.6; Flexi-Post/Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and Parapost/Ketac-Silver, 37.7; The Titanium composite, Ti-Core, had the greatest fracture load values in all instances; the silver-filled glass-ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the Parapost had the least. Both the Flexi-Post and the Vlock post have large bulky heads with many vertical and horizontal

grooves, apparently facilitating the locking of the core material into the post. Pamuk S, Suer E, Panuk E, Gor H, Kutay O, Babacan H. Root fracture with threaded prefabricated posts. J Dent Res 1996;75 IADR Abstract 303:55. Custom cast post have been successful over the years, but studies reveal them to be less retentive than prefabricated posts. The parallel-sided posts have been found more retentive then the tapered posts and the threaded posts have been determined the most retentive post design. But increasing retention may come at the expense of an increased risk of root fracture. The purpose of this study is to determine the effect of threaded post design on root fracture under compressive loading. Three different prefabricated parallel sided parallel posts, Flexi-Post (F), Parapost XT (P) and Flexi-Flange (FF) were used. Test specimens were prepared from sound 70 human maxillary incisors of comparable root lengths. Samples were subjected to compressive force, using a universal testing machine at a crosshead speed of 5 mm/min. with an angle of 135o to the long axes of the teeth was applied, until root fracture occurred. Results were analyzed to establish the statistical significance among the means of the groups. Due to its smaller diameter, roots restored with Parapost XT No. 4.5 had significantly lower fracture resistance compared to roots restored with Flexi-Post No. 2 and 3. Table I. Threaded posts used in this study. Post No. Diameter ParaPost XT 4.5 01.14mm 5.5 01.40mm 6 01.50mm Flexi-Post 2 01.25mm 01.65 w/threads 3 01.50mm 01.90 w/threads Flexi-Flange 2 01.25mm 01.65 w/threads 3 01.50mm 01.90 w/threads Table 2. Mean fracture loads and SD (N). Post Diameter Mean SD ParaPost XT 01.14mm 468.92 87.49 A B 01.40mm 681.19 228.38 01.50mm 632.22 199.39 Flexi-Post 01.25mm 897.71 177.22 A 01.50mm 922.9 264.26 B Flexi-Flange 01.25mm 734.86 264.3 01.50mm 510.27 293.42 Groupings with the same letter are statistically significant. Gur H, Pamuk S, Suer E, Pamuk E, Kutay O. Strength of core materials with different


prefabricated post head design. J Dent Res 1996;75 IADR Abstract 302:55. The mechanical properties of a post and core system may be affected by the design of the post head and the properties of the core material. The purpose of this study was to determine compressive strengths of four core materials retained by five different prefabricated posts heads. To determine the effect of posts head on the compressive and tensile strengths of core materials 100 samples were made. Posts used were ParaPost and ParaPost XT (Coltene/Whaledent, Mahwah, NJ), Flexi-Post, EDS’ AccessPost and World Post (EDS S. Hackensack, NJ) Core materials were Oralloy (Coltene/Whaledent, Mahwah, NJ), Ti-Core (EDS, S.Hackensack NJ), Vitremer (3M, S. Paul, MI) and Ketac-Silver (Espe, Germany). The core was cylindrical and 5mm in diameter. The covering thicknesses of the resin block and loaded with an universal testing machine at a crosshead speed of 5mm/min. Results were then recorded and statistical analysis were made using Kruskal-Wallis and Dunn's multiple comparison test (table 1 and 2). The lowed mean failure load is obtained with Ketac-Silver/ParaPost XT and the highest with Ti-Core/ParaPost combination. Although there is no significant difference among the mean of the groups, Ketac-Silver showed the lowest mean failure load with all post head designs. High retention of the split-shanked threaded post system confirmed. Citation in Dental Abstracts 1996;January/February Vol. 41 No. 1:23. Background - Although prefabricated parallel-threaded posts without a split in the shank are known to provide high retention, they also lead to high stress as a result of active engagement of the dentin by the thread of the post. Some dental practitioners believe that the stress of insertion from a threaded post is acceptable and threaded posts should be used for better retention. Others argue that enough retention and stability can be achieved by using an assortment of prefabricated passive systems and standard cast posts. The manufacturer of the split-shanked threaded post system has climbed that this system's design permits the practitioner to obtain maximum retention with only a threaded post while simultaneously minimizing the stress of insertion and cementation. Furthermore, the forces of occlusion are distributed more evenly with the split-shanked threaded post system than with a parallel passive system. A review of the literature spanning a 10-year period was undertaken to verify the validity of the split-shanked threaded post design known as Flexi-Post. Observations - This review of the literature served to confirm the high retention of the split-shanked threaded post system and dispelled the belief that high retention must be accompanied by high stress. It should be kept in mind that the split-shanked

threaded post is completely different from a solid-shanked threaded post. The ability of the split-shanked post to compress at the shank permits this system to adapt to a post-hole space. The threading process becomes a gradual one during which active engagement of all threads is used as opposed to an assault by the lead thread alone. Conclusions - The efficacy of the split-shanked threaded post system is supported in the literature. Use of this system leads to high retention without accompanying high stress. Clinical significance - A literature review has confirmed the validity of the split-shanked threaded post system, Flexi-Post. Use of this system provides maximum retention with minimal stress of insertion and cementation and leads to more evenly distributed occlusional forces than with a parallel passive system. Cohen BI, Musikant BL, Deutsch AS: A 10-year literature review of a split-shanked threaded post. Compend Contin Educ Dent 1995;16:630-631. A review of 10 years of literature on prefabricated threaded and passive post systems is presented along with recent literature supporting the validity of the split-shanked threaded post design, Flexi-Post. It is important to note that a split-shanked threaded post is altogether different from a solid-shanked threaded post. The research discussed in this article confirms the high retention of the Flexi-Post and dispels the notion that high retention must be accompanied by high stress. Cohen BI, Deutsch AS, Musikant BL. Tratamiento en frio de espigas endodonticas. Anales de Odontoestomatologia 1995;4:134-137. This study determined whether cold treatment at -96o affected the mechanical properties of various compositions and sizes of the Flexi-Post system. The experiment was divided into four groups of posts. The two control groups were made up of untreated stainless steel (50 posts) and titanium alloy (40 posts). In each instance the bending or breaking forces were tested on a universal testing machine. Stainless steel Flexi-Post samples showed a significant (p<0.05) increase in strength, whereas titanium alloy posts showed no significant increase in strength as a consequence of the cold treatment. Kahn FH, Rosenberg PA, Schulman A, Pines M. Comparison of fatigue for three prefabricated threaded post systems. J Prosthet Dent 1996;75:148-53. Post designs may have a direct effect on fracture resistance of endodontically treated teeth. This in vitro study compared the resistance of three


prefabricated threaded post systems (Cytco, Vlock and Flexi-Post) with lateral shearing forces. After endodontics were completed, prefabricated posts were inserted according to the manufacturer's instructions. A silver amalgam core was placed and extracted human teeth were prepared to a standard size with a 1 mm gingival chamber finished on sound dentin. A cast crown was fabricated and cemented and the specimens were thermocycled. The test samples were secured to an Instron testing machine and loaded until failure. Table. Compressive stress to failure (pounds/inch2) Group Count Mean SD Group I, Cytco 15 2725.9 796.5 Group II, Vlock 15 2810.8 1013.5 Group III, Flexi-Post 14 3024.5 1143.6 Group IV, Control 15 2013.6 771.4 Fracture patterns were recorded, fractured surface areas were measured, and compressive stresses were calculated. However, there were no statistically significant differences among threaded pots in each test group. The presence of a threaded post in the pulp space created fractures that were not significantly different from those teeth in which posts were not placed. Within the parameters of the experimental model used in this in vitro study, it was concluded that the designs of the (Cytco, Vlock and Flexi-Post) three threaded post systems tested did not contribute to or reduce radicular fracture in an endodontically treated tooth when restored by use of amalgam core and a veneer crown with a ferrule. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS. Nagwintowane wklady z przecietym trzonem i klasyczne wklady nagwintowane:wlasnosci wytrzymalosciowe oraz rozklad naprezen. Stomatologia Wspotczesna 1996;Vol.3, No.2:104-108. Split-shank threaded posts and threaded posts:tensile properties and stress levels. Two different threaded post designs were measured for tensile loading in a root canal and for the photoelastic stress generated during insertion and cementation. The Flexi-Post system resisted significantly higher tensile loading before failure that did the ParaPost XT. The stresses generated with the Flexi-Post were minimal, while those generated for the ParaPost XT were extreme. Such results indicated that the Flexi-Post may offer a safer and more retentive post system that the ParaPost XT. Cohen BI, Musikant BL, Deutsch AS. Propiedades retentivas de cuatro sistemas de espigas. Anales de Odontoestomatologia 1995;5:159-164.

This study compared the retention of posts in the root for various diameters (1.3 mm and 1.6mm) of three prefabricated post systems (Unity, Filpost and Brasseler with that of the previously reported No. 1 and No. 2 Flexi-Post systems. The experiment divided into three groups comprising 10 samples for each post system studied. In group 2, the Filpost system was cemented both with a resin cement and zinc phosphate cement. Retention values were obtained with a modified universal testing machine. The retention of 1.3mm posts from most to least retentive was Flexi-Post(zinc phosphate)>Filpost (zinc phosphate)> Filpost (resin)>Brasseler (zinc phosphate)> Unity (resin). The retention of 1.6mm posts from most to least was Flexi-Post (zinc phosphate)> Filpost (zinc phosphate)> Brasseler (zinc phosphate)> Unity (resin)> Filpost (resin). The Filpost system achieved higher retention with zinc phosphate cement than it did with resin cement. Lepe X, Bales DJ, Johnson GH. Tensile dislodgment evaluation of two experimental prefabricated post system. Operative Dentistry 1996;21:209-212. This study tested the tensile dislodgment forces of two experimental post designs that are threaded 7 mm into the most coronal aspect of the root. Experimental post systems studied were ParaPost XT-7 (XT-7), ParaPost XT-10 (XT-10) and they were compared to Flexi-Post (FP) and to the Standard ParaPost (SP). The XT-7 prototype post measured 7 mm in length, while all other post systems were 10 mm. The XT-7 and the FP are active post systems that are threaded throughout their entire length. The SP is a passive serrated post system, and the XT-10 is a combination active/passive design that has a 7 mm coronal thread with a passive serrated apical end. All systems tested were titanium alloy except the SP system, which was stainless steel. The purpose of this study was to compare an active and a passive post design to the experimental designs of the XT-7 active post and the combined active/passive design of the XT-10. This study clearly demonstrated that the highest retention was for the Flexi-Post system (FP) (79.2 +9.2), least retention was for the passive post ParaPost (SP) (46.4 + 8.96). The Flexi-Post was statistically more retentive than all the other systems studied. It is important to note that this research was supported by Coltene/Whaledent Inc. Cohen BI, Deutsch AS, BL Musikant. Wplyw niskich temperatur na wlasciwosci fizyczne stalowych i tytanowyh wkladow koronowo-


korzeniowych i narzedzi. Stomatologia Wspolczesna 1996;Vol.3, Nr.4:297-303. This study determined whether cold treatment at -96ºC affected the mechanical properties of various compositions and size of the Flexi-Post system. The experiment was divided into four groups of posts. The two control groups were made up of untreated stainless steel (50 posts) and titanium alloy (40 posts). The two remaining cold treated groups were made up of stainless steel (50 posts) and titanium alloy (40 posts) in each instance the bending or breaking forces were tested on a universal testing machine. Stainless steel Flexi-Post samples showed a significant (p<0.05) increase in strength, whereas titanium alloy posts showed no significant increase in strength as a consequence of the cold treatment. Cohen BI, Pagnillo MK, Condos S Deutsch AS, Musikant BL. Four Different core materials measured for fracture strength in combination with five different endodontic post designs. J Prosthet Dent 1996;76:487-95. The purpose of this in vitro study was to determine the fractural load of four core materials supported by five post designs. This study was divided into 20 groups with 10 samples per group. Specimens were placed in a special jig at a 45 degree angle, and the fracture load values, in pounds, were obtained with the use of a universal testing machine. A 5x4 factorial design was used to compare the fractural strength and a two-way analysis of variance (ANOVA) was used to determine whether the buccolingual, mesiodistal and height dimensions differed across groupings. Mean fracture load values were observed with Flexi-Post dowel/Ti-Core material 277.1 pounds, ParaPost dowel/Tytin silver amalgam 277.3 pounds with the greatest mean values and ParaPost dowel/Ketac-Silver material with the lowest mean value (49.6 pounds). For all posts, Tytin silver amalgam and Ti-Core materials were significantly stronger than Ketac-Silver and GC Miracle Mix material. Ketac Silver and GC Miracle Mix materials did not differ from each other. The greatest loads were recorded for the ParaPost dowel/Tytin silver amalgam combination follow by Flexi-Post dowel/Ti-Core material and Flexi-Flange dowel/Ti-Core material. These values were not statistically different. ParaPost dowel/Ketac Silver material had the lowest fractural load. Results indicated that Ti-Core material is at least as strong as Tytin silver amalgam. Cohen BI, Condos S, Deutsch AS, Musikant BL. Fracture strength of three different core materials in combination with three different endodontic posts. Abstract citation in the Int Endo J 1996;29:51. The purpose of this study was to determine the fracture load for three different core materials

supported by three different post systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine. A 3 X 3 factorial two-way analysis of variance (P<0.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were, Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin, 100.6; ParaPost/Tytin, 134.6; Flexi-Post/ Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and ParaPost/Ketac-Silver, 37.7. The titanium composite, Ti-Core had the greatest fracture load values in all instances: the silver-filled glass ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the ParaPost had the least. Both the Flexi-Post and Vlock post have large bulky heads with many vertical and horizontal grooves, apparently facilitating the locking of the core material into the post. Cohen BI, Condos S, Musikant BL, Deutsch AS. Retentionseigenschaften von geschlitzten Wurzelkanalschrauben. Bei apikaler Kurzung auf verschiedene Langen. ZWR 1996;Vol.105, No.9:471-475. The retention of the post to the root of an endodontically treated tooth is critical for a successful restoration. Modification of the post length to accommodate a specific clinical situation is common. This study compared the retention of No. 1 and No. 2 Flexi-Post restorations shortened apically form 1 to 5 mm with that reported for full-length control No. 1 and No. 2 Flexi-Post dowels. The experimental material was divided into 10 groups with 10 samples in each group. Retentive values were recorded in pounds with a universal testing machine. Analysis of variance with a Tukey-Student range, multiple comparison test showed no statistical differences from apical reductions of 1, 2, 3, and 5 mm including the full-length control Flexi-Post No. 1 system. With 4 mm of apical shortening statistically greater retention was recorded. No statistical differences resulted with apical reductions of 1 to 4 mm or with the full-length control Flexi-Post No. 2 system, but 5 mm of apical shortening caused significantly less retention. For the No. 1 Flexi-Post, no statistical decrease of retention results for apical cutting of 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm as compared to the full length control. For the No. 2 Flexi-Post, no statistical decrease of retention results from apical cutting of 1 mm, 2 mm, 3 mm, and 4 mm as compared to the full length control. 5 mm of apical cutting for the No. 2


Flexi-Post however, results in statistically smaller retention. These results demonstrate that apical reduction of approximately 40 % of the length of the Flexi-Post does not statistically reduce the retention for the post. Cohen BI, Pagnillo M, Condos S, Deutsch AS, Musikant BL. Torsional tests on endodontic posts. Abstract citation Compendium 1996;Vol.17, No.9:860. Increased resistance to torsional forces is an important factor in the restoration of the endodontically treated tooth. In this study, seven different post designs (Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World Post, Vlock and Dentatus post) were cemented into tooth roots using two different post cements (Zinc phosphate and Flexi-Flow). This resulted in 11 different groupings which were subjected to torsional forces in the clockwise direction. In addition, two different directions were used (clockwise and counterclockwise) for the Flexi-Post and Flexi-Flange systems cemented with ZOP and Flexi-Flow. Torsional forces for the groups studied, ranged from 17 oz-inches (Dentatus/ZOP) to 81 oz-inches (Flexi-Post/ZOP). The threaded posts, Flexi-Post and Flexi-Flange resulted in the highest torsional forces obtained. As a result of torsional testing the heads were displaced from the posts. all other specimens from other groups resulted in removal of the posts (Parapost, EDS’ AccessPost, World Post, Vlock and Dentatus) from their corresponding root canals with no head displacement. Analysis were then carried out suing one-way and two-way analysis of variance (ANOVA), followed by Duncan's multiple range test. The only conclusive differences were between groups 11 (Dentatus/ZOP) and all other groups studied. Therefore, no conclusive differences in mean torque was observed for Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World post and Vlock post regardless of cement and direction of torque used. MUDr. V. Zabrodsky, MUDr. R. Jirkalova. Korenove cepy Flexi-Post Ctyrlete zkusenosti s klinickym pouzitim prefabrikovanych korenovych cepu s rozpolcenou korenovou casti. Quintessenz 1996;5:62-66. This article was recently published in Quintessence International in the Czech Republic. The research investigated the retention and stability of the Flexi-Post, Flexi-Flange, Ti-Core and Flexi-Overdenture systems. All these systems were shown to have clinical advantages over commercially available systems. From March 1992 to December 1995 492 posts from the Flexi-Family have been used in clinical cases. The evaluation has been made for 415 posts: 154 Flexi-Posts, 215 Flexi-Flange and 46

Flexi-Overdentures. This represents a 99.76% success rate over a 4 year period for the Flexi-Post. Cohen BI, Condos S, Deutsch AS, Musikant BL. Resistenza a frattura di tre materiali di ricostruzione in combinazione con tre perni endocanalari. Il Dentista Moderno 1196;9:1289-1293. The purpose of this study was to determine the fracture load for three different core materials supported by three different post systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3 x 3 factorial two-way analysis of variance (p<0.0408) was used to test the effects of core material and post type on the fractural resistance. Ti-Core had the greatest fracture load values in all instances, Ketac-Silver had the least. Flexi-Post and Vlock-Post had the greatest fracture load values, while ParaPost had the least. Both Flexi-Post and Vlock Post have large bulky heads with many vertical and horizontal grooves, apparently facilitating the locking of the core material into the post. Cohen BI, Deutsch AS, Musikant BL. Ermudungszyklus-prufungen an sechs Wurzelstiftsystemen. ZWR 1996;12:711-715. This study tested the comparative cyclic fatigue of six prefabricated post systems (Flexi-Post, Flexi-Flange, Vlock, ParaPost, Cytco and EDS’ AccessPost). Cyclic fatigue testing was obtained with an in vitro fatigue machine that simulated clinical fatigue conditions. An instantaneous applied force of 5.0 pounds was applied to each post specimen and data was recorded when post breakages occurred. This experimental design may simulate biting forces and stresses seen for posts in a clinical situation. Most favorable posts were; Flexi-Post, Flexi-Flange, ParaPost and EDS’ AccessPost. Least favorable posts were; Vlock and Cytco posts. Deutsch AS, Cohen BI, Pagnillo M, Condos S, Musikant BL, Cofrancesco G. Fracture Strength of Four Core Materials Supported by Five Post. J Den Res (IADR Abstracts) 1997;76:555. The purpose of this in vitro study was to determine the fractural load of four core materials (Ti-Core, Tytin amalgam, Ketac-Silver and GC Miracle Mix) supported by five post designs (Flexi-Post (FP), Flexi-Flange (FF), EDS’ AccessPost (AP), ParaPost (PP) and C-Post (CP)). The study was divided into 20 groups with each group consisting of 10 samples. A total of 200 recently extracted, single-rooted human teeth were used in this study. Post preparations were made for FP No. 2, FF No. 2, AP No. 2, PP No. 6 and


CP No. 2, all equivalent to a Flexi-Post No. 2 dowel. The posts were luted in the corresponding root canals with zinc phosphate cement and were allowed to set for 1 hour. For Ti-Core and Tytin silver amalgam, no bonding agents were used. Ketac-Silver and GC Miracle Mix were pre-treatment with 40% polyacrylic acid. All cores were prepared freehanded with a 6-to-8 angle and was standardized to a height of 6.0 mm. The tooth-post-core combinations were mounted in acrylic resin blocks and were then placed in 100% humidity at room temperature for 7 days before testing. Specimens were placed in a special jig on a 45 angle and the fracture load values were obtained using (MTS 810) Material Testing Machine with a crosshead speed of 0.635 cm/min. A two-way Analysis of Variance (ANOVA) was used to determine whether the three dimensions, buccolingual, mesiodistal and height differed across groupings. Pearson correlation coefficients were calculated to determine if there were any correlation between fractural strength and any of the three dimensions. None of the tooth parameters differed significantly across posts or cores. A two-way analysis of covariance (ANACOVA) was used to compare mean fractrual strength across all post-core combination. For each ANACOVAs, pairwise multiple comparisons between core types were carried out using Bonferroni-adjusted pairwise independent sample t-test between ANACOVA-adjusted means. As there were six possible pairwise comparisons of cores, a pairwise t-test was considered significant if its p<0.008. Fracture load values (measured in pounds) were: FP/Ti-Core 277.1, FP/Tytin amalgam 187.8, FP/Ketac-Silver 109.3, FP/GC Miracle Mix 111.4; FF/Ti-Core 273.5, FF/Tytin amalgam 234.5, FF/Ketac-Silver 90.9, FF/GC Miracle Mix 110.7, PP/Ti-Core 169.7, PP/Tytin amalgam 277.3, PP/Ketac-Silver 49.6, PP/GC Miracle Mix 72.7, AP/Ti-Core 202.1, AP/Tytin amalgam 232.9, AP/Ketac-Silver 102.6, AP/GC Miracle Mix 121.0, CP/Ti-Core 213.7, CP/Tytin amalgam 189.7, CP/Ketac-Silver 65.3 and CP/GC Miracle Mix 67.9. For all post, Tytin amalgam and Ti-Core are significantly stronger than Ketac-Silver and G-C Miracle Mix which did not differ from one another. The greatest fractural loads were PP/Tytin amalgam with a fractural load of 277.3131.4 follow closely by FP/Ti-Core 277.181.6 and FF/Ti-Core 2743.583.6. PP/Ketac-Silver had the lowest fractural load of 49.618.5. Ti-Core was at least as strong as Tytin amalgam. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Cyclic Fatigue Properties of Four Core Materials Supported by Five Posts. J Dent Res (IADR Abstracts) 1997;76:554. This pilot study concerned the cyclic fatigue of five different endodontic post systems (EDS’ AccessPost (AP), Flexi-Flange (FF), Flexi-Post (FP), ParaPost

(PP), and Vlock (V)) with four different core materials (Tytin Silver amalgam (TSA), Ti-Core (TC), Ketac-Silver (KS) and G-C Miracle Mix (GC)). This study was divided into 20 groups. Each group consisted of 5 samples for a total of 100 samples. A total of 100 recently extracted human single rooted teeth were used. The preparations for the post-holes were performed according to manufacturers' instructions. In this study only stainless steel posts were used. All posts were cemented with zinc phosphate cement to eliminate any difference with cements and was allowed to set for at least 1 hour. Core preparations used for either Ti-Core and Tytin amalgam were etched with a 37% phosphoric acid gel and then Scotchbond Multi-Purpose bonding agent was applied. Ketac-Silver and G-C Miracle Mix core preparations used were etched with 40% polyacrylic acid. Fabrication of each core was completed with the use of a hard copper band as the matrix and cores were then trimmed and cut to a standard height of 6 mm. The tooth/post/core combinations were mounted in acrylic resin blocks and were then placed in 100% humidity for 1 week before testing. The specimens were placed in a special jig on a 30 angle on the buccolingual axis and in vitro cyclic fatigue was performed using fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 pounds was applied to each post and core combination for a test configuration of 4,000,000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Results were: AP/TC 4,000,000, AP/TSA 4,000,000, AP/KS 13957, AP/GC 1949795, FF/TC 4,000,000, FF/TSA 4,000,000, FF/KC 115125, FF/GC 2364217, FP/TC 4,000,000, FP/TSA 4,000,000, FP/KS 196503, FP/GC 3206836, PP/TC 4,000,000, PP/TSA 4,000,000, PP/KC 7876, PP/GC 1127135, V/TC 4,000,000, V/TSA 4,000,000, V/KC 23311 and V/GC 2572832. Two-way analysis of variance (ANOVA) was used to compare groups. All post/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4,000,000 cycles with no failures. All post/core samples with Ketac-Silver failed before the 4,000,000 test cycle configuration with all failures being core failures. All post/core samples with G-C Miracle Mix failed in a similar way. Newman-Keuls multiple comparison test, illustrated that Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Pagnillo MK, Cohen BI, Musikant BL, Deutsch AS. Retention and Photoelastic Properties of Two Endodontic Post Systems. J Dent Res (IADR Abstracts) 1997;76:553. This in vitro study compares the retention of a Flexi-Post No. 2 cemented with either zinc phosphate


cement (ZOP) or Flexi-Flow (FF) resin composite cement to C-Post No. X-80652R cemented with either ZOP or Bisco Crown & Bridge resin composite cement with All-bond 2. In addition, photoelastic stress analyses were performed with two loading conditions; vertical (30 pounds) and oblique at 26 degree angle (30 pounds). The Flexi-Post is a split-shank threaded post and the C-Post is a carbon fiber bound in an epoxy resin, passive double taper tier post. The retentive studied consisted of four groups with 10 specimens per group. All single rooted human teeth used were endodontically instrumented and a post hole was prepared according to the manufacturer's directions. The posts were then cemented into the prepared post holes with zinc phosphate cement (Fleck's zinc cement), FF or Bisco Crown & Bridge with All-bond 2 according to manufacturers' instructions and allowed to set for a minimum of 1 hour. The teeth were mounted in acrylic resin and stored in 100% humidity for 1 week. These groups were subjected to retentive forces, measured in pounds, with a MTS 810 Material Testing Machine with a crosshead speed of 0.638 in/min. In addition, two photoelastic blocks (PMS-5) were prepared with simulated root canals for each post studied. Post holes free of stress were prepared according to manufacturer's instructions for Flexi-Post and C-Post. The posts were cemented into place with zinc phosphate cement. After post cementation the specimens were allowed to set for 24 hours. One-way analysis of variance (ANOVA) for retention data revealed that there were four distinct groupings that differed from each other (p<0.0001). Flexi-Post with FF (336.4±60.2 lbs) had statistically higher retention than Flexi-Post with ZOP (265.9±25.7 lbs) which had statistically higher retention than C-Post with Bisco Crown & Bridge cement with All-bond 2 (60.5±16.6 lbs) which was statistically higher that C-Post with ZOP (38.7±14.3 lbs). Photoelastic analysis indicated minimal stresses for both the Flexi-Post and C-Post in the unloaded state. The C-Post illustrated asymmetrical apically stress patterns, while loaded in both states. The multi-tiered system of the Flexi-Post clearly distributes stress symmetrically, while the C-Post distributes stresses asymmetrically. The symmetric, even stresses and statistically higher retentive strength for Flexi-Post are more favorable than the asymmetric, uneven stresses and relatively low retentive strength for the C-Post. Musikant BL, Cohen BI, Deutsch AS. Modifying Concepts to Optimum Posts. Dentistry Today 1997;16(5):112-113. This article examines rules of post hole instrumentation and post placement as to provide long-term success of the overlying restoration.Rule 1 - Remove as little tooth structure as possible when preparing the post hole. When providing endodontic treatment one should have some idea of the optimum

thickness of a post before access opening acts as a control against excessive widening. The post hole preparation may be wider than the narrowest preparation possible to provide for a post that is strong enough to distribute functional stresses in a safe manner. Rule 2 - Make the post hole as long as possible. This is more prominent in parallel posts than tapered ones. Functional stresses are distributed through the shank of a post in direct relationship to its surface area. The tapered cast post reduces the effective of length. The very thin apical section of this post distributes minimal stresses to the root, in contrast, the coronal section of this post distributes functional stress in a very concentrated area. Because of the destructive potential of the tapered shape, cast posts must be treated with caution when placed to prevent their wedging action. Rule 3 - Accuracy is critical. The first stresses encountered with post placement are insertional ones. Cast posts are an attempt to create an exact duplication of the post hole. Because cement has an absolute minimal thickness between 10 and 20µm, an exact-fitting cast post cannot be fully seated enhancing the wedging action upon insertion. To prevent the stresses of insertion, the accuracy must be modified either by shrinkage in the casting procedure or reduction in the shank after fabrication.Rule 4 - Threaded posts fracture teeth. Threads on a solid shank, parallel or tapered, produce significant insertional stresses and possible destruction. This is because the solid shank allows for no adaptation to the post hole space, forcing a full depth cut into the dentin by the lead thread. If the thread is on a split shank, the post will adapt to the post hole as insertion takes place. The lead thread will cut only a portion of its full depth, reducing the insertional stressed that would have occurred. The full depth of cut is achieved in a graduated manner minimizing and distributing the insertional stresses over the entire length of the shank. The result is high retention with minimal insertional stress. Deutsch AS, Musikant BL, Cohen BI. Rational Predictable Posthole Preparation. Compendium June 97;18(6):626-630. Restoration of the endodontically treated tooth is a common occurrence in everyday dental practice. Unfortunately, clinical posthole preparation seems to be a random technique. Posthole preparation can and should be a simple, easy, and reliable technique when the below questions are answered: 1. How long should the posthole be? Answer; a. 3mm to 5mm of gutta-percha should be left in the apical area of the root to maintain an adequate endodontic seal. b. There should always be at least 1mm of dentin lateral from the apical end of the post to the cementum. 2. How wide should the canal be? Answer; The smaller the diameter of the posthole the better as not to weaken the root. 3. How can the proper width be maintained so that the prefabricated post does not strip in the canal and lose its retention? Answer; The drill from the post system should not enter the canal more than twice. 4. If it is decided to use a cast post, what is the best posthole preparation to maximize retention? Answer; The most retentive cast posts are


ones that use parallel sided post-holes such as that of the ExactaCast burnout post system. 5. Is there an easy way to avoid perforation the root while preparing the canal for the post? Answer; Gates-Glidden drill and Peeso type reamers have noncutting nipples at the tip of the drills that prevent drills from cutting at their apical ends. For this reason, these drills should first be used to prepare 100% of the posthole length and 90% of the width. 6. Clinically, how can the posthole be prepared quickly, easily, and predictably every time? Answer; Precision parallel sided, multi-tiered post systems such as the ExactaCast burnout post system and the Flexi-Flange prefabricated post system provide corresponding drills for a posthole preparation that can be completed quickly, easily and predictably every time. Musikant BL, Cohen BI, Deutsch AS. Fallacious Concepts of Post and Cores. Dentistry Today 1997;16(10):112. This article examines five post and core concepts that while they look good at first, they do not hold up under careful scrutiny. 1. The concept of making the post-hole as narrow as possible: Removing tooth structure makes a root weaker and more prone to fracture. While a narrow post-hole leaves the root stronger, the space created will only accommodate a thin shanked post. The root may be stronger because less dentin has been removed, but the post may be too weak to support the functional stresses of the final restoration. 2. The concept of a cast post being superior because of its accurate fit: Accuracy is a necessity for these restorations to prevent decay at the margins. If the casting has shrunk, placement will create compressive stresses that are well tolerated by dentin because the compressive strength of dentin exceeds 40,000 PSI. The fallacious truth of cast posts’ superiority derives from the uncritical acceptance that they fit the post-hole precisely and precision is a desirable trait. 3. The concept that passive posts produce no stress: A myriad of studies have definitively proven that parallel single-tiered passive posts produce a concentration of apical stresses with the potential of vertical fracture. Passive posts create no stress when they are first placed, but they must dissipate functional stresses just like any other post. Once under function, a passive parallel single-tiered post creates apical stresses because that is the post’s only natural stop. A parallel threaded system has many stops dissipating the stresses through the length of the root. 4. The concept that a fiber reinforced composite post as strong as dentin represents optimum strength: When one compares strength and stiffness of two materials, the samples must be of the same dimension. Because a post is so much thinner than the bulk of dentin that it replaces, it must be significantly stronger and stiffer than an equivalently dimensioned section of dentin. For a relatively thin sectioned post to have the equivalent

strength of dentin in the dimension of a root, the strength must come from stainless steel, titanium, titanium alloy or a ceramic. Fiber-reinforced composites bend much more easily under function than the root dentin. The greater flexure of the post under function creates increased stresses in the surrounding composite core and the bonded and cemented interphases. 5. The concept that an etch and bond sequence creates a restored tooth comparable in strength to the original: Creating the cohesive strength between a post and core equal to that of an intact natural tooth would be a great achievement. Retention studies of a fiber reinforced composite post placed after an eight step etching and bonding procedure did not exceed 60 pounds, far below the strength of a natural tooth. To date, no passive post exceeds 90 pounds of retention because retention is limited to the cohesive strength of the cement which to date does not exceed 90 pounds. This compares poorly with the over 300 pounds of retention found for the most retentive parallel split-shank threaded post design (Flexi-Post) which gain their greater stability by embedding a series of threads into dentin. Cohen BI, Pagnillo M, Condos S, Deutsch AS. Porównanie wytrzymalosci na skrecanie siedmiu róznych typów wkladów koronowo-korzeniowych. Stomatologia Wspólczesna 1997;4(3):194-201. (Paper published in Poland’s Stomatologia Wspólczesna (Polish) comparing the torsional forces for seven endodontic post systems.) Increased resistance to torsional forces is an important factor in the restoration of the endodontically treated tooth. In this study, seven different post designs (Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World Post, Vlock and Dentatus post) were cemented into tooth roots using two different post cements (Zinc phosphate and Flexi-Flow). This resulted in 11 different groupings which were subjected to torsional forces in the clockwise direction. In addition, two different directions were used (clockwise and counterclockwise) for the Flexi-Post and Flexi-Flange systems cemented with ZOP and Flexi-Flow. Torsional forces for the groups studied, ranged from 17 oz-inches (Dentatus/ZOP) to 81 oz-inches (Flexi-Post/ZOP). The threaded posts, Flexi-Post and Flexi-Flange resulted in the highest torsional forces obtained. As a result of torsional testing the heads were displaced from the posts. All other specimens from other groups resulted in removal of the posts (Parapost, EDS’ AccessPost, World Post, Vlock and Dentatus) from their corresponding root canals with no head displacement. Analysis were then carried out using one-way and two-way analysis of variance (ANOVA), followed by Duncan's multiple range test. The only conclusive differences were between groups 11 (Dentatus/ZOP) and all other groups studied. Therefore, no conclusive


differences in mean torque was observed for Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World post and Vlock post regardless of cement and direction of torque used. Cohen BI, Condos S, Musikant BL, Deutsch AS. Wlasciwosci retencyjne wkladow z przecietym trzpiemiem, shroconych w czesci wierzcholkowej. Stomat, Wspolczesna; vol 4, nr 4, 1997, 290-295. (Paper published in Poland’s Stomatologia Wspólczesna (Polish) Retention properties of a split-safted threaded post: Cut at different apical lengths.) The retention of the post to the root of an endodontically treated tooth is critical for a successful restoration. Modification of the post length to accommodate a specific clinical situation is common. This study compared the retention of No. 1 and No. 2 Flexi-Post restorations shortened apically form 1 to 5 mm with that reported for full-length control No. 1 and No. 2 Flexi-Post dowels. The experiment material was divided into 10 groups with 10 samples in each group. Retentive values ere recorded in pounds with a universal testing machine. Analysis of variance with a Tukey-Student range, multiple-comparison test showed no statistical differences from apical reductions of 1, 2, 3, and 5 mm including the full length control Flexi-Post No. 1 system. With 4 mm of apical shortening statistically greater retention was recorded. No statistical differences resulted with apical reductions of 1 to 4 mm or with the full-length control Flexi-Post No. 2 system, but 5 mm of apical shortening caused significant less retention. The Dental Advisor-Plus. 1997;7(6) Flexi-Post ++++ (Essential Dental Systems, Inc., 89 Leuning St., S. Hackensack, NJ) The Dental Advisor Plus Recommedation: Flexi-Post is highly recommended as a threaded post for restoration of non-vital teeth. It received an 86% rating. Flexi-Post is a pre-fabricated, threaded post system with a patented split shank. This design, coupled with the posts multiple tiers, directs insertion stresses to the length of the post and not the root. The post is vented apically with a second tier of increased diameter at the midsection to improve the metal to dentin fit of the post in the coronal portion of the canal. The introductory kit contains 12 posts (4 each of 3 sizes), a depth gauge, primary and secondary reamers, an external and internal wrench, and an extender. Eighteen consultants used Flexi-Post in 210 clinical cases. Flexi-Post was well received because of its ease of use and design features, such as the split shank and the positive seat from the second tier. The post is

easy to fit and threads into place with minimal pressure from the wrench. Size seclection is adequete, and length adjuctment is easily made. The post seats completely with no apparent pressure and adapts well to the prepared canal. The head has sufficient undercuts to retain and amalgam or composite core. Seventy-five percent of consultants indicated that they would purchase and recommend Flexi-Post. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Cyclic Fatigue Testing of Five Endodontic Post Designs Supported by Four Core Materials. J Prosthet Dent 1997;78(4):458-64. This pilot study examined the cyclic fatigue of five endodontic post systems (EDS’ AccessPost, Flexi-Flange, Flexi-Post, ParaPost, and Vlock) with four core materials (Tytin silver amalgam, Ti-Core, Ketac-Silver and G-C Miracle Mix). In vitro cyclic fatigue was performed with a machine designed to simulate masticatory fatigue forces. An instantaneous force of 22.2 N (5 pounds) was applied to each post and core combination for a test configuration of 4,000,000 repetitions, or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way analysis of variance (ANOVA) was used to compare groups. All posts/core samples with Ti-Core composite and Tytin silver amalgam completed the test with no failures. All posts/core samples with Ketac-Silver material failed before the 4,000,000 test cycle configuration and all failures were core failures. All post/core samples with G-C Miracle Mix material failed in a similar manner. Newman-Keuls multiple comparison test illustrated that, with this simulated fatigue test, Ti-Core material and Tytin silver amalgam were superior to both G-C Miracle Mix and Ketac-Silver materials. Cohen BI, Pagnillo MK, Deutsch AS, Musikant BL. Fracture strengths of three core restorative materials supported with or without a prefabricated split-shank post. J Prosthet Dent 1997;78(6):560-565. The aim of this study was to compare the fracture strengths of three restorative materials, a lanthanide reinforced composite (Ti-Core Natural), a silver amalgam (Tytin), and a hybrid glass ionomer (Advance), supported by either a multi-tiered, threaded split-shank post (Flexi-Flange) or with a dentin spur without a post. A total of 60 recently extracted single-rooted human teeth were divided into six groups of 10. All groups were stored at 100% humidity at room temperature for 1 week before testing. Each specimen was placed in a special jig at a 45-degree angle to the buccolingual axis and subjected to a crosshead speed of 0.63 cm/minute until failure. Two-way analysis of variance followed by the Newman-Keuls pairwise multiple comparisons


test were used to compare the results. There was a statistically significant difference between core materials (p < 0.001), but not regarding post conditions. Ti-Core Natural material had a significantly larger mean failure threshold for fracture than either Tytin silver amalgam or Advance material and the latter two core materials (Tytin and Advance) do not differ from each other. There was no statistical difference between Ti-Core material supported by a post and Ti-Core material supported without a post. This study evaluated the resistance for the core materials supported with or without a post. Ti-Core material supported by a split-shank (Flexi-Flange) post recorded statistically significantly higher fracture resistance than all other core materials supported by a post (Tytin silver amalgam and Advance material). An artificial crown was not used to cover the cores, but the results of this study are important because the strength of the cores were tested in a worst case scenario situation. Deutsch AS, Musikant BL, Cohen BI. Racjonalne i w pelni przwidywalne przgotowanie kanalu korzenia zebra pod osadzenie wkladu koronowo-korzeniowego. Stomatologia Wspolczesna; vol 4, nr 6, 1997, 454-457. (Paper published in Poland’s Stomatologia Wspólczesna (In Polish)) Restoration of the endodontically treated tooth is a common occurrence in everyday dental practice. Unfortunately, clinical posthole preparation seems to be a random technique. Posthole preparation can and should be a simple, easy, and reliable technique when the below questions are answered: 1. How long should the posthole be? Answer; a.) 3mm to 5mm of gutta-percha should be left in the apical area of the root to maintain an adequate endodontic seal. b.) There should always be at least 1mm of dentin lateral from the apical end of the post to the cementum. 2. How wide should the canal be? Answer; The smaller the diameter of the posthole the better as not to weaken the root. 3. How can the proper width be maintained so that the prefabricated post does not strip in the canal and lose its retention? Answer; The drill from the post system should not enter the canal more than twice. 4. If it is decided to use a cast post, what is the best posthole preparation to maximize retention? Answer; The most retentive cast posts are ones that use parallel sided post-holes such as that of the ExactaCast burnout post system. 5. Is there an easy way to avoid perforation the root while preparing the canal for the post? Answer; Gates-Glidden drill and Peeso type reamers have noncutting nipples at the tip of the drills that prevent drills from cutting at their apical ends. For this reason, these drills should first be used to prepare 100% of the posthole length and 90% of the width. 6. Clinically, how can the posthole be prepared quickly, easily, and predictably every time? Answer; Precision parallel sided, multi-tiered post systems such as the ExactaCast burnout post system and the Flexi-Flange prefabricated post system provide corresponding drills for a posthole preparation that can be completed quickly, easily and predictably every time.

Wilson NHF, Setcos JC, Dummer PMH, Gorman DG, Hopwood WA, Saunders WP, Hughlock RJ, Hunter MJ. A Split-Shank prefabricated post system: A critical multidisciplinary review. Quintessence Int. 1997;28(11):737-743. A multidisciplinary panel of senior academics and practitioners has evaluated a system of prefabricated threaded split-shank post (Flexi-Post / Flexi-Flange) from published research and their own clinical use. These posts have been compared with requirements of an ideal post system in relation to clinical use, stress effects, stress distribution, retention, loosening and displacement, provision for cores, and biocompatibility. The purpose was to provide this critical review to allow interested clinicians to compare this novel design to other available post systems. Clinical Relevance: These prefabricated post systems, which enable a post and core to be provided in one visit, have been characterized as easy to use, reliable, retentive with low stress, and successful clinical use. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of Three Endodontic Posts Cemented with Five Different Types of Dental Cements. J Prosthet Dent 1998;79(5):520-525. The purpose of this study was to compare the retentive values of three different posts (Flexi-Post, EDS’ AccessPost, and ParaPost) cemented with five different cements (Flexi-Flow, zinc phosphate, Advance, Duet, and Ketac-Cem) plus a control group that consisted of a Flexi-Post No. 2 dowel without cement. A total of 160 recently extracted human single-rooted teeth with crowns removed at the cementoenamel junction were divided into 16 groups with 10 samples per group. Post holes were prepared according to manufacturers' instructions. Posts were then cemented with either Flexi-Flow, zinc phosphate, Advance, Duet, or Ketac-Cem cements. Each sample was placed into a specialized jig and on a tensile testing machine with crosshead speed of 0.638 cm/min applied until failure. A two-way analysis of variance and Newman-Keuls multiple range comparison tests were performed for all cemented groups. A one-way analysis of variance and a Student-Newman-Keuls multiple range comparison test was performed only for the groups with the Flexi-Post dowel, this included the no cement condition. Results were consider to be statistically significant if p<0.05. The Flexi-Post dowel with Flexi-Flow Natural cement obtained the highest retentive value of 303.91 pounds. ParaPost dowel with Duet cement had the lowest retention value of 21.23 pounds. The Flexi-Post dowel had higher mean retention than did EDS’ AccessPost or ParaPost dowels, and EDS’ AccessPost dowel was higher than ParaPost dowel. Flexi-Flow cement had the highest overall mean retention followed, in


decreasing order by zinc phosphate, Advance, Ketac-Cem, and Duet cements. Flexi-Post dowel was the most retentive post studied with values ranging from 303.91 pounds with Flexi-Flow Natural cements to 150.93 pounds without cement. Flexi-Flow cements had a higher overall mean retention than other cements studied. Pagnillo MK, Cohen BI, Musikant BL, Deutsch AS.Retention Strength of Three Posts Cemented with Five Different Dental Cements. J Dent Res 1998;77[Abstract 221]:133. The purpose of this study was to compare and evaluate the retention values of three different posts (Flexi-Post, EDS’ AccessPost, and ParaPost) cemented with five different cements (Flexi-Flow, zinc phosphate (ZOP), Advance, Duet, and Ketac-Cem). This study was divided into 16 groups with 10 specimens per group. A total of 160 recently extracted human single rooted teeth with their crowns removed at the CEJ were used in this study. Post holes were prepared according to manufacturer's instructions and then cemented with either Flexi-Flow, ZOP, Advance, Duet, or Ketac-Cem. The Flexi-Post control group was prepared without cement (Group 16). The cement for each group was allowed to set for 1 hour before being placed into acrylic blocks. The test specimens were then stored in a 100% humidity environment at room temperature for a week before being tested. The test specimens were placed in a specialize jig and tensile strength using a 810 MTS testing machine (crosshead speed of 0.638 cm/min) was measured until posts were removed from their roots. A 3x5 analysis of variance (ANOVA) was used to find any significant interactions between the three levels of posts and the five different cements. This was followed by a one-way ANOVA and the Newman-Keuls (SNK) pairwise multiple comparison test that compared the five cements and the "no-cement condition" for the Flexi-Post only. All results were considered statistically significant if p<0.05. Flexi-Flow ZOP Advance Duet Ketac-Cem No Cement Flexi-Post 303.9 265.9 189.0 160.8 188.4 150.9 EDS’AccessPost 89.7 96.2 88.4 41.7 34.5 pounds (sd) ParaPost 56.2 34.4 51.9 21.2 36.8 Flexi-Post with Flexi-Flow obtained the highest retention value of 303.9 pounds and ParaPost with Duet had the lowest retention value of 21.2 pounds. Flexi-Post had statistically higher retention mean values than did EDS’ AccessPost or ParaPost, with EDS’ AccessPost being higher than ParaPost. Flexi-Flow cement had statistically higher overall retention means followed in decreasing order by ZOP, Advance, Ketac-Cem, and Duet. Flexi-Post was the most retentive post studied with values of 303.9 pounds with Flexi-Flow. Flexi-Flow had statistically higher overall retention means than all other cements studied. The cements based on

resin composite's compositions were stronger than cements based on glass ionomers compositions. Musikant BL, Cohen BI, Deutsch AS. Bledne opinie na temat wkladów koronowo-korzeniowych i zrebu koronowego. Stomat Wspolczesna 1998; Supplement No.1:28-30. (Paper published in Poland’s Stomatologia Wspólczesna (Polish) Fallacious Concepts of Post and Cores) This article examines five post and core concepts that while they look good at first, they do not hold up under careful scrutiny. 1. The concept of making the post-hole as narrow as possible: Removing tooth structure makes a root weaker and more prone to fracture. While a narrow post-hole leaves the root stronger, the space created will only accommodate a thin shanked post. The root may be stronger because less dentin has been removed, but the post may be too weak to support the functional stresses of the final restoration. 2. The concept of a cast post being superior because of its accurate fit: Accuracy is a necessity for these restorations to prevent decay at the margins. If the casting has shrunk, placement will create compressive stresses that are well tolerated by dentin because the compressive strength of dentin exceeds 40,000 PSI. The fallacious truth of cast posts’ superiority derives from the uncritical acceptance that they fit the post-hole precisely and precision is a desirable trait. 3. The concept that passive posts produce no stress: A myriad of studies have definitively proven that parallel single-tiered passive posts produce a concentration of apical stresses with the potential of vertical fracture. Passive posts create no stress when they are first placed, but they must dissipate functional stresses just like any other post. Once under function, a passive parallel single-tiered post creates apical stresses because that is the post’s only natural stop. A parallel threaded system has many stops dissipating the stresses through the length of the root. 4. The concept that a fiber reinforced composite post as strong as dentin represents optimum strength: When one compares strength and stiffness of two materials, the samples must be of the same dimension. Because a post is so much thinner than the bulk of dentin that it replaces, it must be significantly stronger and stiffer than an equivalently dimensioned section of dentin. For a relatively thin sectioned post to have the equivalent strength of dentin in the dimension of a root, the strength must come from stainless steel, titanium, titanium alloy or a ceramic. Fiber-reinforced composites bend much more easily under function than the root dentin. The greater flexure of the post under function creates increased stresses in the surrounding composite core and the bonded and cemented interphases. 5. The concept that an etch and bond sequence creates a restored tooth comparable in strength to the original: Creating


the cohesive strength between a post and core equal to that of an intact natural tooth would be a great achievement. Retention studies of a fiber reinforced composite post placed after an eight step etching and bonding procedure did not exceed 60 pounds, far below the strength of a natural tooth. To date, no passive post exceeds 90 pounds of retention because retention is limited to the cohesive strength of the cement which to date does not exceed 90 pounds. This compares poorly with the over 300 pounds of retention found for the most retentive parallel split-shank threaded post design (Flexi-Post) which gain their greater stability by embedding a series of threads into dentin. Freeman MA, Nicholls JI, Kydd WL, Harrington GW.Leakage Associated with Load Fatigue-Induced Preliminary Failure of Full Crowns Placed over Three Different Post and Core Systems. J Endodontics 1997;24(1):26-32. Thirty -six maxillary central incisors were endodontically treated and restored with a post and core and cast crown. Three different post and core systems were evaluated. Restored teeth fatigue-loaded until preliminary failure of the casting occurred as detected by a strain gauge bonded across the lingual margin of the cast crown. After preliminary failure, fatigue loading was continued for 100,00 load cycles with the crown margin exposed to basic fuschin dye. Teeth were then immersed in dye for 24 hours, sectioned, and evaluated for leakage. There was no significant difference in the number of load cycles required to cause preliminary failure among the three post and core systems (Flexi-Post, ParaPost and cast posts). Leakage occurred in all three groups, with no significant difference between groups. The occurrence of preliminary failure is clinically undetectable, yet it allows leakage between the restoration and tooth that may extend down the prepared post space. Deutsch AS, Musikant BL, Cohen BI. Rational Predictable Posthole Preparation. Iavouapioc 97;16(7):35-40. (Article Published in Greek) Restoration of the endodontically treated tooth is a common occurrence in everyday dental practice. Unfortunately, clinical posthole preparation seems to be a random technique. Posthole preparation can and should be a simple, easy, and reliable technique when the below questions are answered: 1. How long should the posthole be? Answer; a. 3mm to 5mm of gutta-percha should be left in the apical area of the root to maintain an adequate endodontic seal. b. There should always be at least 1mm of dentin lateral from the apical end of the post to the cementum. 2. How wide should the canal be? Answer; The smaller the diameter of the posthole the better as not to weaken the root. 3. How can the proper width be

maintained so that the prefabricated post does not strip in the canal and lose its retention? Answer; The drill from the post system should not enter the canal more than twice. 4. If it is decided to use a cast post, what is the best posthole preparation to maximize retention? Answer; The most retentive cast posts are ones that use parallel sided post-holes such as that of the ExactaCast burnout post system. 5. Is there an easy way to avoid perforation the root while preparing the canal for the post? Answer; Gates-Glidden drill and Peeso type reamers have noncutting nipples at the tip of the drills that prevent drills from cutting at their apical ends. For this reason, these drills should first be used to prepare 100% of the posthole length and 90% of the width. 6. Clinically, how can the posthole be prepared quickly, easily, and predictably every time? Answer; Precision parallel sided, multi-tiered post systems such as the ExactaCast burnout post system and the Flexi-Flange prefabricated post system provide corresponding drills for a posthole preparation that can be completed quickly, easily and predictably every time. Trushkowsky, RD. Esthetic, biologic and restorative considerations in coronal segment reattachment for a fractured tooth: A clinical report. J Prosthet Dent 1998;79(2):115-117. Reattachment of a fractured clinical crown involving minimal invasion of the biologic width can be accomplished without conventional ostectomy and crown lengthening so that satisfactory esthetics can be achieved. Adhesive techniques sometimes in conjunction with traditional mechanical retention, such as a post, can be used to reattach the fractured segment. An esthetics result can be obtained with a minimal number of procedures and cost to the patient. A post and core are often needed for an endodontically treated tooth with substantial loss of coronal tooth structure. Flexi-Post dowel is a parallel, tapered, threaded system with a split shaft in the apical third that diminishes insertion stressed. A vertical vent in the solid core coronal to the split shaft allows escape of luting material and reduces hydrostatic back pressure. The post flexes inwardly as it moves apically, and the initial threads penetrated less than a threaded solid post. Subsequent threads cut only slightly deeper. Boyarsky and Davis demonstrated that, when an active post is desired for restoration of endodontically treated teeth and the manufacturer’s recommended procedures are closely followed, the Flexi-Post dowel may be placed without substantially increasing the risk of fracture. 1998 CRA Dental Product Buying Guide.CRA-Clinical Research Associates Newsletter. 1998;22(1):2&4. Products which were highly rated after clinical field trials:


Flexi-Flange- Excellent overall grade & purchase indicated Cohen BI, Pagnillo MK, Deutsch AS, Musikant BL. Wytrzymalosc na pekanie trzech maaterialow do odbudowy zrebu koronowego z wkladem lub bez wkladu koronowo-korzeniowego z przcietym trzonem. Stomat Wspolczesna 1998;5(2):126-131. (Paper published in Poland’s Stomatologia Wspólczesna (Polish) Fracture strengths of three core restorative materials supported with or without a prefabricated split-shank post). This study evaluated the resistance for the core materials supported with or without a post. Ti-Core material supported by a split-shank (Flexi-Flange) post recorded statistically significantly higher fracture resistance than all other core materials supported by a post (Tytin silver amalgam and Advance material). An artificial crown was not used to cover the cores, but the results of this study are important because the strength of the cores were tested in a worst case scenario situation. The aim of this study was to compare the fracture strengths of three restorative materials, a lanthanide reinforced composite (Ti-Core Natural), a silver amalgam (Tytin), and a hybrid glass ionomer (Advance), supported by either a multi-tiered, threaded split-shank post (Flexi-Flange) or with a dentin spur without a post. A total of 60 recently extracted single-rooted human teeth were divided into six groups of 10. All groups were stored at 100% humidity at room temperature for 1 week before testing. Each specimen was placed in a special jig at a 45-degree angle to the buccolingual axis and subjected to a crosshead speed of 0.63 cm/minute until failure. The results were; 1) Ti-Core without a post 230.8±38.8, 2) Ti-Core with post 213.0±49.5, 3) Tytin amalgam with post 172.8±31.5, 4) Tytin amalgam without post 140.8±57.0, 5) Advance with post 158.3±24.4, 6) Advance without post 133.9±45.5. Two-way analysis of variance followed by the Newman-Keuls pairwise multiple comparisons test were used to compare the results. There was a statistically significant difference between core materials (p < 0.001), but not regarding post conditions. Ti-Core Natural material had a significantly larger mean failure threshold for fracture than either Tytin silver amalgam or Advance material and the latter two core materials (Tytin and Advance) do not differ from each other. There was no statistical difference between Ti-Core material supported by a post and Ti-Core material supported without a post. Musikant BL, Cohen BI, Deutsch AS. Optymalne zmiany koncepcji budowy wkladu. Stomat Wspolczesna 1998;5(1):48-51. (Paper published in Poland’s Stomatologia Wspólczesna (Polish) Modifying concepts to optimum posts)

This article examines rules of post hole instrumentation and post placement as to provide long-term success of the overlying restoration.Rule 1 - Remove as little tooth structure as possible when preparing the post hole. When providing endodontic treatment one should have some idea of the optimum thickness of a post before access opening acts as a control against excessive widening. The post hole preparation may be wider than the narrowest preparation possible to provide for a post that is strong enough to distribute functional stresses in a safe manner. Rule 2 - Make the post hole as long as possible. This is more prominent in parallel posts than tapered ones. Functional stresses are distributed through the shank of a post in direct relationship to its surface area. The tapered cast post reduces the effective of length. The very thin apical section of this post distributes minimal stresses to the root, in contrast, the coronal section of this post distributes functional stress in a very concentrated area. Because of the destructive potential of the tapered shape, cast posts must be treated with caution when placed to prevent their wedging action. Rule 3 - Accuracy is critical. The first stresses encountered with post placement are insertional ones. Cast posts are an attempt to create an exact duplication of the post hole. Because cement has an absolute minimal thickness between 10 and 20µm, an exact-fitting cast post cannot be fully seated enhancing the wedging action upon insertion. To prevent the stresses of insertion, the accuracy must be modified either by shrinkage in the casting procedure or reduction in the shank after fabrication.Rule 4 - Threaded posts fracture teeth. Threads on a solid shank, parallel or tapered, produce significant insertional stresses and possible destruction. This is because the solid shank allows for no adaptation to the post hole space, forcing a full depth cut into the dentin by the lead thread. If the thread is on a split shank, the post will adapt to the post hole as insertion takes place. The lead thread will cut only a portion of its full depth, reducing the insertional stressed that would have occurred. The full depth of cut is achieved in a graduated manner minimizing and distributing the insertional stresses over the entire length of the shank. The result is high retention with minimal insertional stress as illustrated for the Flexi-Post and Flexi-Flange split shank design. Cohen BI, Musikant BL, Deutsch AS. Efecto del tratamiento de frîo en la fuerza del metal. Anales de Odontoestomatologia 1995;5:165-173. (Spanish Article) This study determined whether cold treatment at 96 degrees celsius affected the mechanical properties of various compositions and sizes of the Flexi-Post system. The experiment was divided into four groups of posts. The two control groups were made up of untreated stainless steel (50 posts) and titanium alloy (40 posts). The two


remaining cold-treated groups were made up of stainless steel (50 posts) and titanium alloy (40 posts). In each instance the bending or breaking forces were tested on a universal testing machine. Stainless steel Flexi-Post samples showed a significant (p<0.05) increase in strength, whereas titanium alloy posts showed no significant increase in strength as a consequence of the cold treatment. 1. The cold-treated stainless steel Flexi-Post samples of all different sizes showed a significant increase in bending or breaking force compared with the untreated samples. 2. Titanium alloy Flexi-Post samples that were cold treated showed no difference in bending or breaking force compared with the untreated samples. 3. Cold treatment has great potential in dentistry for increasing the mechanical properties of stainless steel dental instruments. Cohen BI, Condos S, Musikant BL, Deutsch AS. Propiedades Retentivas De La Espiga Hilada De Mango Abierto: Cortada A Diferentes Distancias Apicales. R Cent Ci Bioméd Univ Fed Uberlandia 1996;12(1):51-59. (Brazilian publication, published in Portuguese-Retention properties of a split-shaft threaded post: Cut at different apical lengths) The retention of the post to the root of an endodontically treated tooth is critical for a successful restoration. Modification of the post length to accommodate a specific clinical situation is common. This study compared the retention of No. 1 and No. 2 Flexi-Post restorations shortened apically form 1 to 5 mm with that reported for full-length control No. 1 and No. 2 Flexi-Post dowels. The experimental material was divided into 10 groups with 10 samples in each group. Retentive values were recorded in pounds with a universal testing machine. Analysis of variance with a Tukey-Student range, multiple comparison test showed no statistical differences from apical reductions of 1, 2, 3, and 5 mm including the full-length control Flexi-Post No. 1 system. With 4 mm of apical shortening statistically greater retention was recorded. No statistical differences resulted with apical reductions of 1 to 4 mm or with the full-length control Flexi-Post No. 2 system, but 5 mm of apical shortening caused significantly less retention. 1. There was no significant difference in retention of Flexi-Post No. 1 dowels between the control group and the groups shortened by 1, 2, 3, or 5 mm. 2. The No. 1 Flexi-Post system recorded a statistically significant increase (p<0.011) in retention for posts reduced by 4 mm. 3. There was no significant difference in retention for the Flexi-Post No. 2 system between the full-length control group and the groups shortened by 1, 2, 3, or 4 mm.

4. A statistically significant (p<0.001) difference in retention was observed for the Flexi-Post No. 2 dowel shortened by 5 mm and the remaining groups: The full-length control and 1, 2, 3, or 4 mm apical reductions. 5. Reducing the post shaft length to 4 mm for both the Flexi-Post No. 1 and No.2 dowels did not adversely affect the retention of the post. Ukens H. Flexi-Post and Flexi-Flange for long-term success. European Dental Practitioner 1998;9:72. Before the split-shank concept, clinicians were forced to choose between posts offering high retention accompanied by high stress (conventional screw posts) and low stress/low retention (passive posts). Flexi-Post from Essential Dental Systems, combines high retention with optimum stress distribution. Several independent studies have confirmed the average retention of a Flexi-Post at around 130kg — far higher than any other commercially available post. Passive posts do not exceed 30kgs even with the most advanced bonding agents. At the same time, published research illustrates that the strain of insertion of a Flexi-Post is similar to that of a passive post. Photoelastic studies show that Flexi-Post distributes functional stressed to the root more benignly than passive posts, particularly when these lack a second or third tier. Post without tiers tend to pass functional stress on to the apex. Occlusal, cyclic and other functional forces cause minute movement (micromovement) among the elements of the restoration. While dentin is elastic to a certain degree, all contemporary cements are brittle, and even small movements will cause breakdown and, possibly loss of retention. In cases with little or no coronal dentin, posts — especially passive posts — are often completely embedded in cement with little or no dentin-post contact. Flexi-Flange provides a third tier designed to rest intimately on a shoulder prepared with a special countersink drill. Functional forces are now met by this dentin/post interface in the strong coronal part of the root. Even more importantly, wedge-type forces are converted into far more benign compressive forces, since teeth typically withstand compressive stresses up to seven times better than tensile stresses. The patented Flexi-Post reduces stress of insertion, distributes functional stresses benignly, allows for higher retention, and vents hydrostatic pressure of cementation. The patented Flexi-Flange is ideal for situations with little or no coronal dentin. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS. Comparison of the Retentive and photoelastic properties of two prefabricated endodontic post systems. J Oral Rehabil 1999;26:488-494.


This in vitro study compared the retention and photoelastic stress patterns from two loading conditions, vertical (30 pounds, 133.2N) and oblique at 26 degree angle (30 pounds, 133.2N) for two prefabricated post systems. The post studied were; (1) Flexi-Post (a split-shank threaded post) and (2) C-Post (a carbon fiber bound in an epoxy resin, passive double taper tier post). Two groups with 10 specimens per group were subjected to retentive forces with a universal testing machine (MTS 810 Material Testing Machine). In addition, two photoelastic test blocks were prepared with simulated root canals for each post studied. After cementation the photoelastic blocks were photographed before vertical and oblique loading and after loading. One-way analysis of variance (ANOVA) for retention data revealed a highly significant difference (p< 0.0001) between groups. The Flexi-Post had a statistically higher mean retention force of 265.9 pounds (1180.6N), while the C-Post had a mean of 38.7 pounds (171.8N). Photoelastic analysis indicated minimal stresses for both the Flexi-Post and C-Post in the unloaded state. The C-Post showed asymmetrical apically stress patterns, while loaded in both states. The multi-tiered system of the Flexi-Post clearly distributes stress symmetrically, while the C-Post distributes stresses asymmetrically. The symmetric, even stresses and statistically higher retentive strength for Flexi-Post are more favorable then the asymmetric, uneven and relatively low retentive strength for the C-Post. Comparison of the fracture resistances of pulpless teeth restored with a cast post and core or carbon-fiber post with a composite core. Martinez-Insua A, Da Silva L, Rilo B and Snatana U. J Prosthet Dent 1998;80(5):527-532. This study compared the fracture resistance of 2 types of restorations: teeth restored with prefabricated carbon-fiber posts and composite cores to cast dowel-core restored teeth. A total of 44 recently extracted sound premoloars were randomly distributed into 2 equal groups; group I, restored with prefabricated carbon-fiber post and a composite core; and group II, with custom-cast type III gold alloy post and cores. The size and shape of the posts were identical in the 2 groups. All teeth were fully covered with a nonprecious cast crown. Fracture resistance was measured by applying a point force at 45 degrees to the long angle of the tooth. Mean fracture threshold was 103.7 ± 53.1 kg for group I versus 202.7 ± 125.0 kg for group II whereas in group I, the post-core nearly always failed first. Posts and cores used for the restoration of pulpless teeth should be strong; nevertheless the post should fail before the remaining dental structure in response to mechanical stress. In this study, the failure threshold of carbon-fiber posts was significantly lower than the threshold

for cast posts. Cast posts commonly resulted in tooth fracture at failure. The Lazy Dentist’s Guide to Excellence: 101 Efficiency Tips and Secret Forms of a Top-Producing Dental Practice. Wahl MJ. 1999;2:62. Flexi-Post, a prefabricated post combine the retention of screw-post with the safety (of less likely root fracture) of parallel posts by the use of a patented split-shank. They are wonderful in situations where a post is needed, but there is still significant tooth structure remaining or where a post and backfill is needed under a crown or bridge. Note: For cases with inadequate coronal tooth structure, Flexi-Flange offers similar benefits. Porownanie rozkladu naprezen dla czterech rodzajow wkladow koronowo-korzeniowych za pomoca badania elastoopotycznego. Cohen BI, Condos S, Musikant BL, Deutsch AS. Stomatologia Wspolczesna 1998;5(4):268-272. (Paper published in Poland’s Stomatologia Wspolczesna, Pilot study comparing the photoelastic stress distribution for four endodontic post systems). This pilot study compared stress distribution using photoelastic blocks for both vertical loading and oblique loading (26° angle) for four groups of post systems (Flexi-Post, Flexi-Flange, ParaPost, and EDS’ AccessPost dowels). For each group, three test blocks of photoelastic material were prepared with simulated endodontic canals, and the specimens were then photographed. Minimal stresses were observed for all the posts after cementation in the unloaded state. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable under vertical loading at 134 N and oblique loadings of 89 N and 134 N. Stress patterns were symmetric over the entire length of these posts. Stress distribution for the ParaPost under vertical loading at 134 N generated stress patterns that were asymmetric with concentrated apically as compared to coronally. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were all favorable under loading conditions studied. Post and core combinations tested for retention. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Dental Abstracts 1998;43(5):250. Retention of posts is a major factor in successful treatment involving endodontic therapy and post and core restoration. This study compared the retention of three endodontic posts cemented with five different materials and compared them with a control. Specimens were 160 recently extracted single-rooted teeth. Crowns removed at the cemento-enamel junction and teeth were divided into 16 groups of 10. One group was treated with a Flexi-Post No. 2 dowel without cement (control). The appropriate post hole


was made according to manufacturers instructions for the three stainless steel dowels tested: Flexi-Post, EDS’ AccessPost, and ParaPost. Five groups of each dowel were used to test each of the cements: Flexi-Flow Natural (resin composite), ZOP (zinc phosphate), Advance (hybrid glass ionomer), Duet (hybrid glass ionomer), and Ketac-Cem (glass ionomer). Specimens were tensile tested until the post was removed. Results were analyzed by post and by the post/cement interactions. The Flexi-Post dowel had the highest mean retention rate, followed by EDS’ AccessPost. The Flexi-Post dowel cemented with Flexi-Flow Natural had the highest retentive value (303.91 pounds). The ParaPost dowel cemented with Duet had the lowest value (21.23 pounds). Flexi-Flow cement had the highest total mean retention, followed by ZOP, Advance, Ketac-Cem, and Duet. Retention was influenced significantly by both the post and cement used. Post-related differences did not remain constant when different cements were used. Combinations of posts and cements demonstrated significant differences in retention. Dissolution of cement, root caries, fracture, and retrofit of post and cores. Rosen H. J Prosthet Dent 1998;80:511-3. Cement dissolution, root caries, and fracture of abutments can result in severe los of tooth structure, often with concomitant pulpal involvement. Removal of a fixed partial denture (FPD) or a segment of the FPD commonly provides acceptable access for debridement. Considerable tooth structure is frequently lost so a new FPD is indicated with additional apical extension of the preparation. In certain situations, this apical extension of the finish line is facilitated by surgical crown lengthening. The new FPD needs to engage as much sound tooth structure as possible to provide improved retention and better protection against recurrence of dental caries and root fracture. Extensive loss of coronal tooth structure often precludes the use of cast post and cores. Prefabricated parallel-sided, serrated, or threaded posts can be made more retentive without removal of sound tooth structure. (These posts include the patented, multi-tiered, split-shank Flexi-Post). Prefabricated posts and cores can also be constructed in 1 appointment. Initial Failure of Post/Core Systems Under Compressive-Shear Loads. Wong EJ, Ruse ND, Greenfeld RS, and Coil JM. J Dent Res (IADR Abstract #2269) 1999;78:389. The objective of this study was to compare the compressive-shear loads at which initial failure occurred in two post and core systems. After embedding in acrylic, the anatomical crowns of 34 extracted anterior teeth were removed, and their canals were instrumented to file size 45 using the

step-back technique. Gates Glidden drills were used to flare the coronal one-third of the canals. Canals were obturated with gutta percha and Roth 801 sealer, using the formed cone technique. Root canals were prepared to receive either a ParaPost™ or Composipost™, and teeth were paired based on matching root dimensions. Posts were cemented using Fuji I luting cement prior to resin-bonded composite core build-ups employing One-Step™ adhesive and Core-Flo™ in celluloid crown forms. Fourteen pairs of teeth were loaded until initial failure was detected visually by monitoring load-displacement curves. Three pairs of teeth were not loaded, and served as controls. All teeth were then immersed in basic fuchsin dye for 96 hours, ground, and evaluated for leakage. A paired t-test was performed on the loading data. Results indicated that there was a significant difference in initial failure between the two post and core systems. Roots with the ParaPost™ system required a greater load (92.91 N± 6.44) than roots with the Composipost™ system (62.50 N ± 3.88) for initial failure to occur (p<0.05). Leakage was evident in both post/core groups, which was different than in the controls. They conclude that the initial failure occurs with the smaller loads in Composipost™ - restored teeth than in ParaPost™ - restored teeth. Christensen GJ, Christensen W, Hunsaker K, Larson T, & Christensen RP (Clinical Research Associates, Provo, UT 84604, USA) J Dent Res (IADR Abstract #3421) 1999;78:533. Recently, new post materials have been introduced. This study compared 7 post types (see table below) currently on the market. Methods: Test 1) Ultimate Strength of Post & Core Buildups - Extracted human maxillary incisors were sectioned at the facial CEJ & treated for endo. Posts were placed per manufacture's instructions, & Corepaste buildups (height & Diam = 4mm) placed after thermocycling 2,500 x in 5º-55º C water, samples were broken using a rounded point force applied 45º from the occlusal on the lingual build up surface. Test 2) Yield Strength of Posts - Group 1 (control) received no treatment, group 2 was fatigued 15,000 cycles with an oscillating force of 5-50 N, group 3 was soaked for 24 hrs in 37º C water. All posts were embedded in delrin with 3mm extending perpendicular to the surface & broken on a 45º angle. Data were analyzed using A0V & Fisher's LSD (p<0.05). Results: Test 1) Statistically, 6 of 7 posts were as strong as "Human Tooth, & one (Fiber) was weaker, 6 of 7 posts were stronger than the "Core Buildup only, & one (Fiber) was statistically, the same. Breaks occurred mainly at the buildup/post interface. Test 2) Fatigue cycling did not weaken any posts statistically. Carbon, Carbon/Zirconium, & Ceramic posts were statistically weaker when stored in water. Posts do not increase tooth strength.


Traditional metal posts maintained in their original strength better than non-metal posts. Post Material - Brand Test 1 Test 2 Note: n_ 5 for all test groups. Tooth Control Fatigued Control Soaked All results reports in Newtons. Buildup Yield Yield Yield Used a MTS 810 at 1mm/min. Break Force Force Force Stainless Steel - ParaPost 678±74 179±23 162±11 153±22 Titanium (99%) - Filpost 646±56 164±26 138±3 151±22 Carbon - C-Post 634±112 90±12 81±20 74±11 Titanium Alloy - ParaPost 623±38 238±22 215±36 222±36 Ceramic - Cerapost 617±67 549±91 490±152 365±37 Carbon / Zirconium - Aestheripost 568±64 102±19 97±7 5±13 Human Teeth - Control 568±91 n/a n/a n/a Core Buildup only - Control 404±100 n/a n/a n/a Fiber - Ribbond 397±91 n/a n/a n/a

Esthetics Post Placement. Essential Dental Systems, Inc. Contemporary Esthetics 1998;2(6)30-32. The first and most important function of the post is not esthetics, but the ability to support the restoration with the greatest long-term stability. The split-shank design of the Flexi-family (Flexi-Post, Flexi-Flange, Flexi-Overdenture) of post creates an architecture that integrates the needs of a supportive post and high retention with those of the root, minimal insertional stresses, and the even distribution of functional stresses. To make this solid foundation esthetics, the manufacture has developed tooth-colored, long-term (at least 5 years), fluoride-releasing composite cements and core materials, namely Flexi-Flow Natural and Ti-Core Natural. Together with an opaquing layer these products mask the color of the metal post and improve its esthetics. In addition, Ti-Core and Flexi-Flow also come in grey (reinforced with titanium) to differentiate from the lighter tooth structure when necessary. Badanie wytrzymalosci zmeczeniowej szesciu róznych wkladów koronowo-korzeniowych. Cohen BI, Deutsch AS, Musikant BL. Stomatologia Wspólczesna 1998;5(6):429-433. (Paper published in Poland’s Stomatologia Wspolczesna, Cyclic fatigue testing of six endodontic post systems) In a new experimental approach, in vivo biting force was compared with in vitro dynamic instantaneous forces delivered by a fatigue testing machine. Six prefabricated post systems were studied. The maximum average anterior in vivo biting force of 60 lbs was found to be in the same range as an instantaneous applied force of 5.0 lbs. All samples for Flexi-Flange, Flexi-Post, Parapost, and EDS’ AccessPost showed no failure after 2,000,000 repetitions. Sixty percent of Vlock and all the Cytco post systems failed before the completion of the test configuration (failed before 2,000,000

cycles). It is believed that this experimental setup comes closer to simulating the biting forces seen clinically than does static loading applied to a test sample. LA FUERZA DE FRACTURA DE TRES TIPOS DE MATERIALES PARA EL MUÑON EN COMBINACION CON TRES ESPIGAS ENDODONTIACALES DISTINTAS. Cohen BI, Condos S, Deutsch AS, Musikant BL. R. Cent. Ci. Bioméd. Univ. Fed. Uberlândi. 1997;13(1):69-76. (Spanish text published in Brazil “Fracture strength for three different core materials in combination with three different posts”. ) The purpose for this study was to determine the fracture load for three different core materials supported by three different posts systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3x 3 factorial two-way analysis of variance (p<.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were: Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin 100.6; Parapost/Tytin, 134.6; Flexi-Post/Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and Parapost/Ketac-Silver, 37.7; The Titanium composite, Ti-Core, had the greatest fracture load values in all instances; the silver-filled glass-ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the Parapost had the least. Both the Flexi-Post and the Vlock post have large bulky heads with many vertical and horizontal grooves, apparently facilitating the locking of the core material into the post. Prezentacja nowego systemu wkladów koronowokorzeniowych Flexi-Flange dla zastosowan klinicznych. Opis przypadku. Musikant, BL, Cohen BI, Deutsch AS. Stomatologia Wspólczesna 1999;6(2):35-37. (Article printed in Polish: Presentation of a new, Flexi-Flange Post system for clinical use.) Advantages of a new post design, Flexi-Flange, is described which incorporates a split-shank parallel threaded post with a flange that seats into an occlusal countersunk dentin space. This case report describes placement of three Flexi-Flange posts in a first bicuspid, canine and central incisor. The Flexi-Flange system offers, high retention of the post in the root, superior distribution of stresses under insertion and under function, and long term resistance to metal fatigue.


Retencja trzech rodzajów wkladów koronowokorzeniowych cementowanych za pomoca pieciu róznych cementów. Cohen BI, Pagnillo M, Newman I, Musikant BL, Deutsch AS. Stomatologia Wspólczesna 1999;Supp 1:24-29. (Article printed in Polish: Retention of three endodontic posts cemented with five dental cements.) The purpose of this study was to compare the retentive values of three different posts (Flexi-Post, EDS’ AccessPost, and ParaPost) cemented with five different cements (Flexi-Flow, zinc phosphate, Advance, Duet, and Ketac-Cem) plus a control group that consisted of a Flexi-Post No. 2 dowel without cement. A total of 160 recently extracted human single-rooted teeth with crowns removed at the cemento-enamel junction were divided into 16 groups with 10 samples per group. Post holes were prepared according to manufacturers' instructions. Posts were then cemented with either Flexi-Flow, zinc phosphate, Advance, Duet, or Ketac-Cem cements. Each sample was placed into a specialized jig and on a tensile testing machine with crosshead speed of 0.638 cm/min applied until failure. A two-way analysis of variance and Newman-Keuls multiple range comparison tests were performed for all cemented groups. A one-way analysis of variance and a Student-Newman-Keuls multiple range comparison test was performed only for the groups with the Flexi-Post dowel, this included the no cement condition. Results were consider to be statistically significant if p<0.05. The Flexi-Post dowel with Flexi-Flow Natural cement obtained the highest retentive value of 303.91 pounds. ParaPost dowel with Duet cement had the lowest retention value of 21.23 pounds. The Flexi-Post dowel had higher mean retention than did EDS’ AccessPost or ParaPost dowels, and EDS’ AccessPost dowel was higher than ParaPost dowel. Flexi-Flow cement had the highest overall mean retention followed, in decreasing order by zinc phosphate, Advance, Ketac-Cem, and Duet cements. Flexi-Post dowel was the most retentive post studied with values ranging from 303.91 pounds with Flexi-Flow Natural cements to 150.93 pounds without cement. Flexi-Flow cements had a higher overall mean retention than other cements studied. Cohen BI, Pagnillo MK, Newman I, Musikant BL, and Deutsch AS. Retention of Four Endodontic Posts Cemented with Composite Resin Cements. AGD (Gen Dent) 2000;48(3):320-324. The purpose of this in vitro study was to test and compare the retentive values of the Cerapost ceramic post cemented with Universal Post Cementation Kit II system (Brasseler USA) to the split-shanked Flexi-Flange, ExactaCast (a burnout/cast post), ExactaCast with grooved dentin, and ParaPost dowels, all cemented with Flexi-Flow Natural cement (Essential Dental Systems). This study was divided into 5

group with 10 samples per group. A total of 50 recently extracted human single-rooted teeth with their crowns removed at the cementoenamel junction (CEJ) were used. The post-hole for each group was made according to manufacturer’s instructions. A post-hole length of 10 mm was used to standardized the post-hole length for all groups studied. One of the ExactaCast groups had their post-holes grooved with a retentive grooving drill. All groups except the Cerapost dowel group were cemented with a lanthanide reinforced fluoride releasing Bis-GMA based composite cement, Flexi-Flow Natural (FF) according to manufacturer’s instructions. For all groups, the cement was allowed to set for 1 hour before specimens were placed into acrylic blocks. The test specimens were then stored in a 100% humidity environment at room temperature for 24 hours before being tested. The tensile strength test was performed using a 810 MTS testing machine (Material Testing System) with a crosshead speed of 0.638 cm/minute until failure. Failure occurred when the post was removed from the tooth or with post head breakage. One-way analysis of variance (ANOVA) followed by a Student-Newman-Keuls (SNK) multiple comparisons test was used to compare the mean retention. Results were consider to be statistically significant if p < 0.05. The retention of all groups (in pounds) was as follows; Flexi-Flange/FF 270.4 ±34.3, ExactaCast grooved/FF 90.6 ±21.3, ExactaCast/FF 63.9 ±18.9, ParaPost/FF 70.3 ±19.5 and Cerapost/Universal cement 23.4 ±7.8. ANOVA revealed a significant difference between groups (p<0.0001). The SNK test showed that the Flexi-Flange post recorded highest level of retention followed by ExactaCast with grooved dentin walls which were greater than ParaPost dowel and ExactaCast without grooved dentin walls. The Cerapost with Universal cement system had statistically lower retention than all other groups studied. From the results of this study the following conclusions were drawn; the threaded, split-shank design of the Flexi-Flange (270.4 pounds) offers the greatest retention. The serrated design of the ExactaCast cast post in conjunction with grooved dentin walls offers the greatest retention of all passive post designs studied with a retention value of 90.6 pounds. The smooth wedge-shape design of the Cerapost ceramic post is the least retentive post design with a retentive value of 23.4 pounds. Penugonda B, Cohen BI, Pagnillo MK, Schulman A, Hittelman E. Torsional Forces on Crowns supported by Post-Core Restorations. J Dent Res 2000;79:546 (Abstract 3223). The purpose of this in vitro study was to investigate the effect of torsion on a crown supported by a titanium-reinforced composite core material (Ti-Core core material) and three different endodontic post


system (Flexi-Post, EDS’ AccessPost and ParaPost). This study was divided into three groups with 10 specimens per group. A total of 30 recently extracted human single-rooted (incisors) teeth with their crowns removed at the cementoenamel junction were used. Post-hole preparations were created following manufacturer’s instructions. The post-holes were prepared to a depth of 10 mm. All posts were cemented in place using Flexi-Flow cement. Scotchbond Multi-Purpose bonding agent was used as the bonding system for all groups. All cores were fabricated with Ti-Core with titanium core build-up material using hard copper bands as the matrix. The Ti-Core core build-up material was placed and allowed set for one hour before being shaped and trimmed with 0.5 mm shoulder and beveled on tooth using diamond burs. Polyvinyl siloxane (PVS) impressions of the teeth were taken to fabricate metal crowns on epoxy dies. Polished metal crowns were cemented with zinc phosphate cement. The test specimens were then placed into acrylic blocks and stored in 100% humidity for 1 week before being tested. The test specimens were placed in a special jig and a clockwise torsional force was applied. The torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorder in inch x ounces. A one-way ANOVA followed by a Student-Newman-Keuls (SNK) and Scheffe comparison tests were performed and results were considered significant if p<0.05. Results of the mean torque loading was as follows; Group 1, Flexi-Post 162.2 ± 52.2 in x oz, Group 2, EDS’ AccessPost 77.2 ± 30.3 in x oz, and Group 3, ParaPost 60.9 ± 28.4 in x oz. The results of the ANOVA revealed a significant difference p<0.001. The SNK and Scheffe comparison test revealed that the Flexi-Post group had significantly greater resistance to torque loading than the EDS AccessPost and ParaPost groups, which were statistically similar to each other. It was concluded that post design has an effect on torsional resistance of a crown supported by a titanium reinforced core build-up and post. The active threaded split-shank design of the Flexi-Post dowel offers greater resistance to torsional loading than the passive posts studied. Deutsch AS, Cohen BI, Pagnillo MK, Newman I, Musikant BL. Post-head Retention of Two Core Materials Using Three Post Designs. J Dent Res 2000;79:546 (Abstract 3222). The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s

instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS’ AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Pagnillo MK, Cohen BI, Newman I, Musikant BL, and Deutsch AS. Retention of Four Endodontic Post Designs Cemented with Composite Resin Cements. J Dent Res 2000;79:546 (Abstract 3220). The purpose of this in vitro study was to test and compare the retentive values of the Cerapost ceramic post cemented with Universal Post Cementation Kit II system (Brasseler USA) to the split-shanked Flexi-Flange, ExactaCast (a burnout/cast post), ExactaCast with grooved dentin, and ParaPost dowels, all cemented with Flexi-Flow Natural cement (Essential Dental Systems). This study was divided into 5 group with 10 samples per group. A total of 50 recently extracted human single-rooted teeth with their crowns removed at the cementoenamel junction (CEJ) were used. The post-hole for each group was


made according to manufacturer’s instructions. A post-hole length of 10 mm was used to standardized the post-hole length for all groups studied. One of the ExactaCast groups had their post-holes grooved with a retentive grooving drill. All groups except the Cerapost dowel group were cemented with a lanthanide reinforced fluoride releasing Bis-GMA based composite cement, Flexi-Flow Natural (FF) according to manufacturer’s instructions. For all groups, the cement was allowed to set for 1 hour before specimens were placed into acrylic blocks. The test specimens were then stored in a 100% humidity environment at room temperature for 24 hours before being tested. The tensile strength test was performed using a 810 MTS testing machine (Material Testing System) with a crosshead speed of 0.638 cm/minute until failure. Failure occurred when the post was removed from the tooth or with post head breakage. One-way analysis of variance (ANOVA) followed by a Student-Newman-Keuls (SNK) multiple comparisons test was used to compare the mean retention. Results were consider to be statistically significant if p < 0.05. The retention of all groups (in pounds) was as follows; Flexi-Flange/FF 270.4 ±34.3, ExactaCast grooved/FF 90.6 ±21.3, ExactaCast/FF 63.9 ±18.9, ParaPost/FF 70.3 ±19.5 and Cerapost/Universal cement 23.4 ±7.8. ANOVA revealed a significant difference between groups (p<0.0001). The SNK test showed that the Flexi-Flange post recorded highest level of retention followed by ExactaCast with grooved dentin walls which were greater than ParaPost dowel and ExactaCast without grooved dentin walls. The Cerapost with Universal cement system had statistically lower retention than all other groups studied. From the results of this study the following conclusions were drawn; the threaded, split-shank design of the Flexi-Flange (270.4 pounds) offers the greatest retention. The serrated design of the ExactaCast cast post in conjunction with grooved dentin walls offers the greatest retention of all passive post designs studied with a retention value of 90.6 pounds. The smooth wedge-shape design of the Cerapost ceramic post is the least retentive post design with a retentive value of 23.4 pounds. Cohen BI, Musikant BL, Deutsch AS. Elastooptyczne porównawcze badania naprezen wykazywanych przez nagwintowane wklady pelne i z przecietym trzonem. Stomat. Wspólczesna 1999;6(3):38-40. (Published in Polish: Comparison of the photoelastic stress for a split-shank threaded post versus a threaded post.) This study compared the stress distribution during insertion and after cementation for two prefabricated endodontic posts, (1) a split-shank threaded post, and (2) a threaded post with no split in the shank. Three test blocks of photoelastic material were prepared

with simulated endodontic canals for each group studied. Specimens were then photographed after insertion and cementation. Minimal stresses were observed for the post with a split (group 1) throughout the length of the shaft, whereas asymmetric patterns of stresses for the post without a split (group 2) were present. Stress distribution for the post without a split were concentrated more apically rather than coronally. The presence of a split reduces insertion and cementation stresses for this post system. The split also acts as a vent during the cementation of the post into the canal and minimizes stress concentration during cementation. Stockton LW, Williams PT. Retention and Shear Bond Strength of Two Post Systems. Oper Dent 1999;24:210-216. The purpose of this study was to compare the retention and shear strength of teeth restored with the Para Plus post (P) and the C post (C1 and C2) systems. Twenty-four P, C1, and C2 posts each were placed 7 mm into recently extracted and endodontically treated maxillary anterior roots and luted with Ketac-Cem and Bis-Core respectively. In addition, 13 samples of each post type had a Bis-Core composite core placed. The tensile retention strength of the post and shear strength of the post and core restorations when the core was loaded buccolingually at 45º to the roots’ long axis were determined at a strain rate of 1.3 mm/min. The C2 posts required significantly more tensile force (P<0.001) to remove them than the P or C1 posts. The shear strength of the post/core restorations was not significantly different (P<0.04). The C1 restorations had 12 root fractures, the C2 restorations had 11 root fractures, and the P samples had six root fractures. It was concluded that the lack of stiffness of the C post adversely affected the success of these restorations. The author also concludes, the use of C posts may be undesirable for most cases. Cohen BI, Pagnillo MK, Newman I, Musikant L, Deutsch AS. Pilot study of the cyclic fatigue characteristics of five endodontic posts with four core materials. J Oral Rehabil 2000;27:83-92. This pilot study concerned the cyclic fatigue of five different endodontic post systems. (EDS’ AccessPost, Flexi-Flange, Flexi-Post, ParaPost and Vlock with four different core materials (Tytin Silver amalgam, Ti-Core, Ketac-Silver and G-C Miracle Mix). In vitro cyclic fatigue was performed using a fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 lbs. was applied to each post and core combination for a test configuration of 4,000,000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way


ANOVA was used to compare groups. All posts/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4,000,000 test cycle without failures. All post /core samples with Ketac-Silver failed before the 4,000,000 test cycle test cycle configuration, all as a result of core failures. All post/core samples with G-C Miracle Mix failed in a similar way. The Newman-Keuls multiple comparison test illustrated that Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Similar fatigue test results are found in the literature. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of a core material supported by three post head designs. J Prosthet Dent 2000;83(6):624-628. The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS’ AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied

were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Cohen BI, Penugonda B, Pagnillo MK, Schulman A, Hittelman E. Torsional resistance of crowns cemented to composite cores involving three stainless steel endodontic post designs. J Prosthet Dent 2000;84(1):38-42. The purpose of this in vitro study was to investigate the effect of torsion on a crown supported by a titanium-reinforced composite core material (Ti-Core core material) and three different endodontic post system (Flexi-Post, EDS’ AccessPost and ParaPost). This study was divided into three groups with 10 specimens per group. A total of 30 recently extracted human single-rooted (incisors) teeth with their crowns removed at the cementoenamel junction were used. Post-hole preparations were created following manufacturer’s instructions. The post-holes were prepared to a depth of 10 mm. All posts were cemented in place using Flexi-Flow cement. Scotchbond Multi-Purpose bonding agent was used as the bonding system for all groups. All cores were fabricated with Ti-Core with titanium core build-up material using hard copper bands as the matrix. The Ti-Core core build-up material was placed and allowed set for one hour before being shaped and trimmed with 0.5 mm shoulder and beveled on tooth using diamond burs. Polyvinyl siloxane (PVS) impressions of the teeth were taken to fabricate metal crowns on epoxy dies. Polished metal crowns were cemented with zinc phosphate cement. The test specimens were then placed into acrylic blocks and stored in 100% humidity for 1 week before being tested. The test specimens were placed in a special jig and a clockwise torsional force was applied. The torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorder in inch x ounces. A one-way ANOVA followed by a Student-Newman-Keuls (SNK) and Scheffe comparison tests were performed and results were considered significant if p<0.05. Results of the mean torque loading was as follows; Group 1, Flexi-Post 162.2 ± 52.2 in x oz, Group 2, EDS’ AccessPost 77.2 ± 30.3 in x oz, and Group 3, ParaPost 60.9 ± 28.4 in x oz. The results of the ANOVA revealed a significant difference p<0.001. The SNK and Scheffe comparison test revealed that the Flexi-Post group had significantly greater resistance to torque loading than the EDS’ AccessPost and ParaPost groups, which were statistically similar to each other. It was concluded


that post design has an effect on torsional resistance of a crown supported by a titanium reinforced core build-up and post. The active threaded split-shank design of the Flexi-Post dowel offers greater resistance to torsional loading than the passive posts studied. O’Keefe KL, Miller BH, Powers JM. In Vitro Tensile Bond Strength of Adhesive Cements to New Post Materials. Int J Prosthodont 2000;13:47-51. The purpose of this study was to measure the in vitro tensile bond strength of 3 types of adhesive resin cements to stainless steel, titanium, carbon fiber-reinforced resin, and zirconium oxide post materials. Disks of post materials were polished to 600 grit, air abraded, and ultrasonically cleaned. Zirconium oxide bonding surfaces were pretreated with hydrofluoric acid and silanated. Bis-Core, C&B Metabond, and Panavia cements were bonded to the post specimens and placed in a humidor for 24 hours. Post specimens were debonded in tension. Means and standard deviations (n=5) were analyzed by 2-way analysis of variance. Failure modes were observed. Panavia 21 provided the highest bond strengths for all types of post materials, ranging from 22 MPa (zirconium oxide) to 37 MPa (titanium). C&B Metabond bonded significantly more strongly to stainless steel (27 MPa) and titanium (22 MPa) than to zirconium oxide (7 MPa). Bis-Core results were the lowest, ranging from 16 MPa (stainless steel) to 8 MPa (zirconium oxide). In most cases, bonds to carbon fiber post materials were weaker than to stainless steel and titanium, but stronger than to zirconium oxide. In general, higher bond strengths resulted in a higher percentage of cohesive failures within the cement. Panavia 21 provided the highest bond strength to all post materials, followed by C&B Metabond. In most cases, adhesive resins had higher bond strengths to stainless steel, titanium, and carbon fiber than to zirconium oxide. Musikant BL, Cohen BI, Volovich Y, Deutsch AS. Retention of a Flexi-Flange post with bonded Ti-Core cores. J Den Res (Abstract 1774), 2001;80:257. The use of dentinal bonding agents has achieved wide acceptance in dentistry. However, there are limited studies on their retention of a post with a core bonded to tooth structure using various dentinal bonding agents. The purpose of this study was to determine the retentive values of a Flexi-Flange post (Essential Dental Systems, Inc. S. Hackensack, NJ) with a Ti-Core Natural core (Essential Dental Systems, Inc.) using various dental multi-step bonding agents (Tenure Multi-step (Den-Mat Corp. Santa Maria, Calif), All-Bond 2 (Bisco, Inc. Itasca, Ill.) and 3m Scotchbond (3M Dental Products Division St. Paul, Minn.)) compared to a control

where no bonding agent was used. The experiment was divided into 3 groups and a control with 10 specimens per group. The retentive strengths were evaluated after 24 hours on a 810 MTS universal testing machine with a crosshead speed of 0.638 cm/min. The results were; Tenure 264.5 + 52.7 pounds, All-Bond 2 291.4 + 42.1 pounds, 3M Scotchbond 297.9 + 37.9 pounds and the control 270.4 + 34.3 pounds. A one-way ANOVA illustrated that none of the groups differed statistically from each other and from the control (P< 0.2448). The values for the retention of the Flexi-Flange/ Flexi-Flow/Ti-Core using various dentinal bonding agents ranged from a low of 264.5 pounds (Tenure) to a high of 297.9 pounds (3M Scotchbond) with a control (without bonding agent) of 270.4 pounds. All of the retention for the Flexi-Flange post resulted from the retention of the split-shank threaded portion (mechanical retention) of the post which mechanically engages the root canal. The phenomenon where mechanical retention is greater and more significant than chemical retention (from dentinal bonding agents) has been described previously in the literature.

Purton DG, Love RM, Chandler NP. Rigidity and Retention of Ceramic Root Canal Posts. Operative Dent 2000;25:223-227. CeraPost (1.2 mm coronal diameter, ceramic/tapering/smooth posts) and ParaPosts (1.25 mm stainless-steel, parallel/serrated posts) were tested for rigidity by means of a three-point bending test. To test retention in roots, ceramic posts were cemented using one of three protocols: (1) glass-ionomer cement, (2) silane coupling agent and composite resin cement, or (3) sandblasted post surface, silane coupling agent, and composite resin cement. Stainless-steel posts were cemented with composite resin. The tensile force required to dislodge the post, following four weeks of storage in water, was recorded. Data were compared using Student’s t-test and Mann-Whitney U analysis. The stainless-steel, parallel/serrated posts cemented with composite resin were significantly more retentive than the smooth/tapering Cerapost. Cohen BI, Pagnillo M, Newman I, Musikant BL, Deutsch AS. Badania wytrzymalosciowe pieciu róznych wkladów koronowo-korzeniowych zastosowanych z czterema róznymi materialami do odbudowy zrebu koronowego. Przeglad Stomatologiczny 2000;January:18-21. (Published in Polish: Pilot study of the cyclic fatigue characteristics of five endodontic posts with four core materials.) This pilot study concerned the cyclic fatigue of five different endodontic post systems. (EDS’ AccessPost, Flexi-Flange, Flexi-Post, ParaPost and Vlock with four different core materials (Tytin Silver amalgam,


Ti-Core, Ketac-Silver and G-C Miracle Mix). In vitro cyclic fatigue was performed using a fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 lbs. was applied to each post and core combination for a test configuration of 4,000,000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way ANOVA was used to compare groups. All posts/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4,000,000 test cycle without failures. All post /core samples with Ketac-Silver failed before the 4,000,000 test cycle test cycle configuration, all as a result of core failures. All post/core samples with G-C Miracle Mix failed in a similar way. The Newman-Keuls multiple comparison test illustrated that Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Similar fatigue test results are found in the literature. Cohen BI, Musikant BL, Deutsch AS. Prezeglad 10-letniej literatury dotyczacej aktywnych wkladow koronowo-korzeniowych z przeceta czescia korzeniowa. Stomatologia Wspolczesna 2000;7(2):40-42. (Published in Polish: A 10-year literature review of a split-shanked threaded post.) A review of 10 years of literature on prefabricated threaded and passive post systems is presented along with recent literature supporting the validity of the split-shanked threaded post design, Flexi-Post. It is important to note that a split-shanked threaded post is altogether different from a solid-shanked threaded post. The research discussed in this article confirms the high retention of the Flexi-Post and dispels the notion that high retention must be accompanied by high stress. Cohen BI, Musikant BL, Deutsch AS. Zastosowanie kliniczne systemu wkladow koronowo-korzeniowych Flexi-Flange. Quintessence dla lekarzy stomatologów 2000;TomVII(Numer2):69-73. (Published in Polish: The Flexi-Flange post system and its clinical usage.) The clinical case below, reports on the use of No. 2 Flexi-Flange posts to restore a first premolar and canine. The unique design of the Flexi-Flange includes a parallel threaded primary shank that is split along its longitudinal axis, a second tier for close adaptation of the post to the root at the point where coronal flares often exist and a wider third tier that fits within a machined root faced area. The result of a Flexi-Flange post is a post with a large metal to dentin interface without the need of a wide taper. The advantages of a tiered system over a tapered system include significantly less lateral stresses during insertion and function. The Flexi-

Flange system offers; high retention of the post in the root, superior distribution of stresses under insertion and under function, and long term resistance to metal fatigue. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Retentive Properties of a Split-Shank Threaded Post with a Core Using Three Different Multi-Step Bonding Agents. Oral Health 2000;90(10):43-51. This study determined the retentive values of a Flexi-Flange post with a Ti-Core Natural core using various dental multi-step bonding agents (Tenure, All-Bond 2 and 3m Scotchbond) compared to a control where no bonding agent was used. The experiment was divided into 3 groups and a control with 10 specimens per group. The retentive strengths were evaluated after 24 hours on a 810 MTS universal testing machine with a crosshead speed of 0.638 cm/min. A one-way ANOVA illustrated that none of the groups differed statistically from each other and from the control ( P< 0.2448). The values for the retention of the Flexi-Flange/ Flexi-Flow/Ti-Core using various dentinal bonding agents ranged from a low of 264.5 pounds (Tenure) to a high of 297.9 pounds (3M Scotchbond) with a control (without bonding agent) of 270.4 pounds. All of the retention for the Flexi-Flange post resulted from the retention of the split-shank threaded portion (mechanical retention) of the post which mechanically engages the root canal. The phenomenon where mechanical retention is greater and more significant than chemical retention ( from dentinal bonding agents) has been described previously in the literature. The Dental Advisor. October 2000;17(8):5. The patented split shank Flexi-Flange post delivers maximum retention (in the root and of core material) with minimal insertional stress. By the incorporation of a flange the patented Flexi-Flange provides stability in situations where there is inadequate coronal dentin and excessive occlusal forces. Available in both titanium and stainless steel. The Dental Advisor recommends this product giving it a 91% clinical rating with 4 1/2 stars. This rating was the highest given to a active post. Musikant BL, Deutsch AS, Cohen BI. Prezentacja nowego systemu wkladów koronowo-korzeniowych Flexi-Flange dla zastosowan klinicznych. Twój Przeglad Stomatologiczny 2000;2:20-21. (Article Published in Polish: Presentation of a new Flexi-Flange post system for clinical use.) Advantages of a new post design, Flexi-Flange, is described which incorporates a split shank parallel threaded post with a flange that seats into an occlusal countersunk dentin space. This case report describes placement of three Flexi-Flange posts in a first


bicuspid, canine and central incisor. The Flexi-Flange system offers, high retention of the post in the root, superior distribution of stresses under insertion and under function, and long term resistance to metal fatigue. Cohen BI, Pagnillo MK, Condos S, Musikant BL, Deutsch AS. Wlasciwosci retencyjne wkladów z przecietym trzpieniem, skróconych w czesci wierzcholkowej. Twój Przeglad Stomatologiczny 2000;3:40-43. (Article Published in Polish: Retention properties of a split-shaft threaded post: Cut at different apical lengths.) The retention of the post to the root of an endodontically treated tooth is critical for a successful restoration. Modification of the post length to accommodate a specific clinical situation is common. This study compared the retention of No. 1 and No. 2 Flexi-Post restorations shortened apically form 1 to 5 mm with that reported for full-length control No. 1 and No. 2 Flexi-Post dowels. The experimental material was divided into 10 groups with 10 samples in each group. Retentive values were recorded in pounds with a universal testing machine. Analysis of variance with a Tukey-Student range, multiple comparison test showed no statistical differences from apical reductions of 1, 2, 3, and 5 mm including the full-length control Flexi-Post No. 1 system. With 4 mm of apical shortening statistically greater retention was recorded. No statistical differences resulted with apical reductions of 1 to 4 mm or with the full-length control Flexi-Post No. 2 system, but 5 mm of apical shortening caused significantly less retention. 1. There was no significant difference in retention of Flexi-Post No. 1 dowels between the control group and the groups shortened by 1, 2, 3, or 5 mm. 2. The No. 1 Flexi-Post system recorded a statistically significant increase (p<0.011) in retention for posts reduced by 4 mm. 3. There was no significant difference in retention for the Flexi-Post No. 2 system between the full-length control group and the groups shortened by 1, 2, 3, or 4 mm. 4. A statistically significant (p<0.001) difference in retention was observed for the Flexi-Post No. 2 dowel shortened by 5 mm and the remaining groups: The full-length control and 1, 2, 3, or 4 mm apical reductions. 5. Reducing the post shaft length to 4 mm for both the Flexi-Post No. 1 and No.2 dowels did not adversely affect the retention of the post. Cohen BI, Condos S, Musikant BL, Deutsch AS. Porównanie rozkladu naprezen dla czterech rodzajów wkladów koronowo-korzeniowych za pomoca badania elastooptycznego. Compendium Stomatologli 2000;3:21-24. (Article Published in Polish: Pilot study comparing the photoelastic stress distribution for four endodontic post systems.) This study compared the

stress distribution under function using photelastic blocks for both vertical or compressive loading and oblique loading (on a 26 degree angle) for four post systems, groups 1-4 Flexi-Post, Flexi-Flange, Parapost and EDS’ AccessPost. Three test blocks of photoelastic material were prepared with simulated endodontic canals for each group studied. Specimens were then photographed. Minimal stresses were observed for all the posts studied after cementation in the unloaded state. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable under compressive loading at 30 pounds and stress patterns were symmetric over the entire length of the post. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable under oblique loadings of 20 and 30 pounds and stress patterns were symmetric over the entire length of the post. Stress distribution for the ParaPost under compressive loading at 30 pounds showed stress patterns which were asymmetric with concentration of stresses apically as compared to coronally. Stress distribution for the ParaPost under oblique loadings of 20 and 30 pounds were asymmetric with stress concentrated apically as compared to coronally. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Comparison of the Photoelastic stress properties for different post-core combinations. Oral Health 2001;91(10):63-72. This study compares two different core materials (Ti-Core and GC Miracle Mix) supported by two different endodontic post systems (Flexi-Post and Para-Post) for photoelastic stress distribution in an oblique loading condition with a 26 degree angle at 20 pounds. Four groups of post/core systems blocks of photoelastic materials were prepared with simulated endodontic canals (using a plastic that approaches the strength of dentin), and the specimens (photoelastic block/cemented post/core combinations) were then photographed in the unloaded and loaded states. Minimal stresses were observed for all post/core combinations in the unloaded state. The specimens prepared with the multi-tiered, Flexi-Post clearly distributed stress symmetrically and coronally in the loaded oblique state, while the specimens with the single tiered Para-Post showed asymmetrical apically and coronally stress patterns. Post/core combinations with Ti-Core composite were more stable than post/core combinations with GC Miracle Mix glass ionomer. The symmetric, even stresses for the Flexi-Post/core systems are more favorable than the asymmetric, uneven stresses for the Para-Post/core systems. Post/core combinations with Ti-Core a titanium reinforced composite are more stable and favorable than post/core combinations with GC Miracle Mix glass ionomer.


Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention values of post head design and core materials compared. Dental Abstracts 2000;45(6):270. The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Comparison of torsional resistance for natural human teeth. Dentistry (UK) 2003 In Press.

Torsional resistance of an endodontic restorative system is an important consideration for a long-term restoration. However, currently no studies have established the amount of torsional resistance necessary for a tooth reconstruction; no cut-off or threshold limit values for success or failure are known in the literature. This study determined the torsional resistance of the natural human teeth by investigating a possible correlation between teeth dimensions and their resistance to torsional force. This study also compares the torsional resistance of post-core components which make up a restoration from previously published studies. Three groups of 10 specimens per group were studied. A total of 30 recently extracted human single rooted (incisors) teeth were used. All teeth were measured and recorded at the cementoenamel junction (CEJ), buccolingually (B/L) and mesiodistally (M/D). The groupings were selected according to teeth dimension. The extracted teeth were mounted in acrylic resin blocks. Test specimens were placed into a special jig and a clockwise torsional force was applied. Torsional force was measured on a Lebow torque transducer and recorded on a Hewlett-Packard recorder measured in inch X ounces. A One-way analysis of variance (ANOVA) and SNK was used to test for statistical significance (P < 0.05). The torsional resistance values (inch X ounce) were: group 1; 33.97 + 9.20 ( B/L = 5 mm, M/D = 3-4 mm), group 2; 37.67 + 17.68 (B/L = 6 mm, M/D = 4-5 mm) and group 3; 76.15 + 33.71 (B/L = 7-8 mm, M/D = 5-6 mm). SNK revealed that group 3 had significantly greater resistance to torsional loading than groups 1 and group 2. Groups 1 and 2 were statistically similar to each other. The tooth dimensions have an effect on torsional resistance of the tooth. The torsional resistance of teeth with B/L = 7-8 mm and M/D = 5-6 mm are significantly greater than the torsional resistance of teeth with B/L = 5-6 mm and M/D = 3-5 mm. Are Ceraposts really this bad? Reality: The Reviews 2000;128:21-22.* This article reviewed three articles which have tested retention values of the Cerapost to answer the question - Are CeraPosts really this bad?: 1) Cohen BI, Pagnillo MK, Newman I, Musikant BL, and Deutsch AS. Retention of Four Endodontic Posts Cemented with Composite Resin Cements. AGD (Gen Dent) 2000;48(3):320-324. Upon critique of this article Flexi-Flange, a patented split-shank threaded post, was found be significantly more retentive than the passive CeraPost. 2) Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of a core material supported by three post head designs. J Prosthet Dent 2000;83(6):624-628. Upon critique of this article the CeraPost was found to have poor adhesion to core materials. Reality stated; it is obvious that metal-free


posts should also have heads with macro-mechanical retention, similar to those on metal posts. Miracle Mix is obsolete and has no place in modern dentistry. 3) O’Keefe KL, Miller BH, Powers JM. In Vitro Tensile Bond Strength of Adhesive Cements to New Post Materials. International J Prosthodon 2000;13(1):47-51.Upon critique of this article, relating to the bond strength of resin three resin cements (Panavia 21, C&B Metabond and Bis-Core), Panavia 21 was found to have the highest bond strength (to metal as well as carbon-fiber). Reality does point out that; “Unfortunately, due to its anaerobic setting mechanism and especially with the addition of the ED Primers, it is difficult to use Panavia 21 when cementing post. There is always a danger it will begin to set at the bottom of the posthole before you can seat the post.” *From Reality’s Publication, Reality: The Reviews 2000;128:21-22. Phan DC, Nagy WW, Dhuru VB, Karczewski MB, Ziebert AJ. Effect of Sterilization and Disinfection Procedures on Prefabricated Posts. J Den Res (Abstract 1259), 2001;80:1259. A prefabricated post may be inserted in the canal and examined until the correct size is chosen. For those posts that were tried but not used, a potential for blood borne contamination exists. This study evaluated six prefabricated post types for alteration in surface detail or other visible morphological change after disinfection and sterilization. Three metallic and three non-metallic post types were evaluated, ParaPost - titanium, Flexi-Post - stainless steel , Filpost - pure titanium, C-Post - carbon fiber, FiberKor - glass fiber, and the Cosmo Post - zirconium oxide. Two posts of each type were subjected to three cycles of disinfection (alkaline glutaraldhyde, phenolic, sodium hypochorite) and sterilization (steam - regular and flash, dry heat, ethylene oxide, chemical vapor). Specimens were examined with a 10X optical microscope and a 550X (SEM), and baseline and post exposure photomicrographs were made. The white FibreKor post exhibited a greenish hue when removed from the phenolic disinfection solution suggesting the porous nature of the post body, and the post was slightly darkened after dry heat sterilization at 165° C, suggesting additional polymerization of the resin matrix. Metallic and zirconium oxide posts are physically stable when subject to three cycles of commonly used dental office disinfection and sterilization protocol. Fiber/resin posts show surface changes, and steam or ethylene oxide sterilization is recommended. Finger WJ, Ahlstrand W, Fritz UB. Evaluation of the radiopacity of fiber-reinforced resin posts. J Dent Res (Abstract 1113) 2001;80:666.

To determine the radiopacity of resin fiber posts before and after cementation in extracted human canines, and to evaluate their appearance on dental radiographs by clinical acceptability scores. One titanium and 7 resin fiber posts were investigated: Komet/Titanium (TIT), Æstheti-Plus (AES), FiberKor (FIK), Light-post/rtd (LPR), LightPost/Dentatus (LPD), Mirafit (MIR), Snowlight (SNL), and Snowpost (SNP). Radiographs of the separate posts and of the posts seated with Panavia 21 EX in endodontically treated prepared canine roots were produced. The radiodensities were determined with a densitometer and expressed in mm Al-equivalents. Sixteen radiographs of the cemented posts (two of each brand) were presented in random order to 20 dental practitioners for ranking by decreasing radiodensity and characterization of the radiographic appearance on a 5-step scale: 1 (good), 2 (adequate), 3 (acceptable), 4 (not acceptable), 5 (no radiopacity). The data was statistically analyzed by one-way ANOVA and Duncan's post-hoc test at p>0.05. Ranking of the separate posts: TIT > SNL, SNP > FIK > LPR, LPD > MIR. Ranking of the cemented posts: TIT > SNL, SNP > FIK, LPD, AES, MIR, LPR. The dentist’ ranking from highest to lowest radiopacity was: TIT > SNL, SNP > FIK > LPD, MIR > LPR > AES. The ranking clinical acceptability was: TIT(1.0) > SNL(2.2), SNP(2.5) > FIK(3.3.) > LPD(4.2), MIR(4.2), LPR(4.6), AES(4.6). The results showed that resin fiber posts are considerably less radiopaque than titanium (metallic) posts. Only three of the seven fiber posts evaluated fulfilled the requirement of acceptable radiographic appearance. Schmage P, Sohn J, Nergiz I, Platzer U. Various Conditioning Methods Influencing the Retention of Root Posts. J Dent Res (Abstract 1305) 2001;80:690. In order to achieve a high root post retention the usage of composites for the post fixation was advised. For the various composite cements different conditioning methods are recommended by the manufacturers, nevertheless the effects of not following them are unclear. This study aimed to measure the bonding strengths of passive tapered root posts inserted with composite cements using different conditioning methods. The root canals of 140 extracted teeth were prepared for sandblasted Titanium Erlangen posts (Brasseler USA, Savannah, USA) of size 11/ length 12mm. Groups of 10 posts were fixed using four composites (Compolute, ESPE, Seefeld, Germany; Flexi-Flow Cem. Essential Dental Systems, NJ, USA; Panavia 21 EX, Kurary, Osaka, Japan: Twinlook, Heraeus-Kulzer, Dormagen, Germany) and the following three conditioning methods respectively: no conditioning, etching, etching/ bonding. Panavia was also used as recommended with a primer. For comparison 10


posts were inserted using a conventional zincphosphate cement (Tenet, Vivadent, Schaan, FL). A tensile force test (Instron 1026) was performed after moist storage for 24 hours and thermocycling. The results were statistically analyzed using the ANOVA-test and the Scheffé-correction. The highest retentive strengths corresponded with the manufacturers conditioning recommendations for Compolute (352±76N) and for Twinlook (430N±78N) using etching and bonding and for Flexi-Flow using no conditioner (475N±104N). The results using Panavia with etching and bonding (442N±97N) instead of primer (375N±77N) did not prove to be statistically significantly different. In all other groups the results decreased significantly if he manufacturers instructions for conditioning were not followed. There were no significant difference between the composites and the conventional cement (414N±102N). Flexi-Flow composite cement resulted in statistically similar retention and the use of Flexi-Flow composite was simpler where no conditioner was needed. Flexi-Flow also had the added benefit of being the only composite cement with 5+ years of documented fluoride release data. Rathke A, Heintze SD, Zappini G. Cyclic Loading of Incisors Restored with Different Post Systems. J Dent Res (Abstract 1431) 2001;80:705. Occlusal stress may result in the failure of post and core build-ups. The aim of this study was to evaluate the fatigue resistance of prefabricated posts covered with metal copings by submitting them to cyclic loading. Thirty-five extracted human maxillary incisors of similar dimensions were decapitated, root filed and embedded in acrylic blocks with simulated periodontal ligaments. Post spaces were prepared to a depth of 8 mm. Five groups of 7 specimens each were compared: a 1.5 mm diameter titanium post (Mooster, CM) (A), a 1.7 mm diameter zirconia post (Cosmopost, Ivoclar) (B), a 1.4 mm diameter fiber post (Aesthetiplus, RTD) (C), and experimental fiber posts of 1.5mm (D) and 2.0 mm in diameter (E). The posts were cemented with zinc phosphate cement. The specimens were stored 37ºC water for 48 hours, then cyclically loaded with 25N peak load at an angle of 45º to the axial direction in an universal testing machine (Zwick 1465). Every 250 cycles (frequency of 0.2 Hz), the peak was increased by 25 N until post failure. Failure modes were yielding (A) and post fracture (B, C, D, E). The mean loading cycles and standard deviations were: 1475±66 (A), 1045±93 (B), 767±69 (C), 761±134 (D), and 1160±143 (E). The mean equivalent loads and standard deviations were: 128 ± 10 N (A), 68 ± 12 N (B), 40 ± 6 N (C), 40 ± 12 N (D), and 83 ± 18 N. (E). For both variables, ANOVA post Tukey test showed significant differences (p<0.001) between (A) and other groups. No statistically significant differences (p>0.05) were found between (C) and (D) or (B) and (E). Metal

posts demonstrated higher fatigue resistance than non-metal posts. Raygot CG, Chai J, Jameson L. Fracture Resistance and Primary Failure Mode of Endodontically Treated Teeth Restored with a Carbon Fiber-Reinforced Resin Post System In Vitro. Int J Prosthodont 2001;14(2)141-145. This study was undertaken to characterize the fracture resistance and mode of fracture of endodontically treated incisors restore with cast post-and-core, prefabricated stainless steel post, or carbon fiber-reinforced composite post systems. Ten endodontically treated teeth restored with each technique were subjected to a compressive load delivered at a 130-degree angle to the long axis until the first sign of failure was noted. Then fracture load and the mode of fracture were recorded. The results showed that carbon-fiber posts did not improve the fracture resistance of endodontically treated central incisors when compared to metallic posts. Musikant BL, Cohen BI, Deutsch AS. Current Trends in Post, Cores, and Restorative Crowns. Dentistry 2001;5:30-33. This article evaluated the recent developments in restorative dentistry, uncovering their pitfalls in critical areas such as; post retention, insertional stress, distribution of functional stress, retention of core material. The Flexi-Post and Flexi-Flange post systems lead these categories by providing a maximum post retention of 220 lbs., minimal insertional stress by the use of a patented split-shank design, multi-tiered design for distribution of functional stress and, coupled with Ti-Core resin-composite core material, provide a long-term restoration. Cohen BI, Condos S, Musikant BL, Deutsch AS. Wytrzymalosc na zlamanie trzech roznych materialow, zastosowanych w polaczeniu z trzema rodzajami standardowych wkladów koronowo-korzeniowych, odbudowy zrebu koronowego. Compendium Stomatolgil 2000;4:13-15. (Paper published in Poland’s Compendium Stomatolgil (In Polish) Fracture strength for three different core materials in combination with three different endodontic posts.) The purpose for this study was to determine the fracture load for three different core materials supported by three different posts systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3x 3 factorial two-way analysis of variance (p<.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were: Flexi-Post/Ti-Core,


204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin 100.6; Parapost/Tytin, 134.6; Flexi-Post/Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and Parapost/Ketac-Silver, 37.7; The Titanium composite, Ti-Core, had the greatest fracture load values in all instances; the silver-filled glass-ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the Parapost had the least. Both the Flexi-Post and the Vlock post have serrated post heads with many vertical and horizontal grooves which facilitate retention. Cohen BI, Pagnillo MK, Deutsch AS, Musikant BL. Wytrzymalosc na pekanie trzech materialow do odbudowy zrebu koronowego z wkladem lub bez wkladu koronowo-korzeniowego z przecietym trzonem. Compendium Stomatolgil 2001;1:7-11. (Paper published in Poland’s Compendium Stomatolgil (In Polish) Fracture strengths of three core restorative materials supported with or without a prefabricated split-shank post.) The aim of this study was to compare the fracture strengths of three restorative materials, a lanthanide reinforced composite (Ti-Core Natural), a silver amalgam (Tytin), and a hybrid glass ionomer (Advance), supported by either a multi-tiered, threaded split-shank post (Flexi-Flange) or with a dentin spur without a post. A total of 60 recently extracted single-rooted human teeth were divided into six groups of 10. All groups were stored at 100% humidity at room temperature for 1 week before testing. Each specimen was placed in a special jig at a 45-degree angle to the buccolingual axis and subjected to a crosshead speed of 0.63 cm/minute until failure. Two-way analysis of variance followed by the Newman-Keuls pairwise multiple comparisons test were used to compare the results. There was a statistically significant difference between core materials (p < 0.001), but not regarding post conditions. Ti-Core Natural material had a significantly larger mean failure threshold for fracture than either Tytin silver amalgam or Advance material and the latter two core materials (Tytin and Advance) do not differ from each other. There was no statistical difference between Ti-Core material supported by a post and Ti-Core material supported without a post. This study evaluated the resistance for the core materials supported with or without a post. Ti-Core material supported by a split-shank (Flexi-Flange) post recorded statistically significantly higher fracture resistance than all other core materials supported by a post (Tytin silver amalgam and Advance material). Yang HS, Lang LA, Guckes AD, Felton DA. The effect of thermal change on various dowel-and-

core restorative materials. J Prosthet Dent 2001;86:74-80. Severe thermal stresses caused by food-induced temperature changes may result in dowel-and-core failure. This study investigated the influence of thermal stresses on various combinations of dowel-and-post materials of a restored endodontically treated incisor. A 2-dimensional finite element model was constructed in a labiolingual cross-sectional view of a maxillary central incisor, a dowel, a core, and the supporting tissues to investigate thermal stress distribution. Four combinations of dowel-and-core materials were used: (1) gold/gold, (2) stainless steel/resin composite, (3) stainless steel/amalgam, and (4) carbon fiber-reinforced composite/resin composite. For thermal analysis, a cold irritant (0°C) was applied on the outer surface of a metal-ceramic crown for 7 seconds. The metal dowel and core generated lower thermal stresses (metal dowels were the most stable) in the restorations and dentin than the nonmetallic dowel and core (non-metallic dowels were the least stable). Stress level is closely related to the degree of thermal gradient. The nonmetallic dowel and cores generated greater thermal stresses than metal dowel and cores. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Photoelastic Stress Properties for different Post-Core Combinations. J Dent Res 2002;81(Abstract 3478):A-428. The use of photoelastic stress analysis has been shown to illustrate the stress distribution for various prefabricated and cast post systems. However, there are limited studies investigating the photoelastic stress distribution for endodontic post/core systems. The purpose of this study was to compare two different core materials; Ti-Core (Essential Dental Systems, Inc.) and GC Miracle Mix (GC Corporation), supported by two different endodontic post systems -Flexi-Post (Essential Dental Systems, Inc.) and Para-Post (Coltene/Whaledent) for photoelastic stress distribution in an oblique loading condition (20 pounds) at a 26 degree angle. Four groups of post/core systems blocks of photoelastic materials were prepared with simulated endodontic canals (using a plastic that approaches the strength of dentin); group 1, Flexi-Post No. 1 / Ti-Core, group 2, Flexi-Post No. 1 / GC Miracle Mix, group 3, Para-Post No. 1 equivalent / Ti-Core and group 4, Para-Post No. 1 equivalent/ GC Miracle Mix. Only stainless steel posts (Flexi-Post No.1- a split-shank, multi-tiered prefabricated post design and Para-Post- a passive single tiered prefabricated post) were used for this study and zinc phosphate cement was used to cement each post into its simulated canal preparation. Specimens (photoelastic block/cemented post/core combinations) were then positioned in a special jig on a universal testing machine (Model CETM 922MTT20/1, Comten Industries) with oblique


loading at 20 pounds and color photographs of each specimen was recorded in the unloaded and loaded states. Despite this gentle loading condition, the GC Miracle Mix core groups failed with coronal core damage (photoelastic data however, was possible to obtain at this loading condition), whereas no core damage was observed for the Ti-Core groups. Minimal stresses were observed for all post/core combinations in the unloaded state. The specimens prepared with the split-shank multi-tiered, Flexi-Post clearly distributed stress symmetrically and coronally in the loaded oblique state, while the specimens with the single tiered Para-Post showed asymmetrical apically and coronally stress patterns. Post/core combinations with Ti-Core composite were more stable than post/core combinations with GC Miracle Mix glass ionomer. The symmetric, even stresses for the Flexi-Post/core systems are more favorable than the asymmetric, uneven stresses for the Para-Post/core systems. Post/core combinations with Ti-Core a titanium reinforced composite are more stable and favorable than post/core combinations with GC Miracle Mix glass ionomer. Deutsch AS, Cohen BI, Volovich Y, Musikant BL. Torsional Resistance for Natural Human Teeth an In Vitro Study. J Dent Res 2002;81(Abstract 1256):A-174. Torsional resistance of an endodontic restorative system is an important consideration for a long-term restoration. However, currently no studies have established the amount of torsional resistance necessary for a tooth reconstruction; no cut-off or threshold limit values for success or failure are known in the literature. This in vitro study determined the torsional resistance of the natural human teeth by investigating a possible correlation between tooth dimensions and their resistance to torsional forces. This study also compares the torsional resistance of post-core components which make up a restoration from previously published studies. Three groups of 10 specimens per group were studied. A total of 30 recently extracted human single rooted (incisors) teeth were used. All teeth were measured at the cementoenamel junction (CEJ), buccolingually (B/L) and mesiodistally (M/D) with the use of an electronic digital caliper. The groupings were selected according to teeth dimension; group 1 B/L= 5 mm and M/D= 3 to 4 mm, group 2 B/L= 6 mm and M/D =4 to 5 mm, and group 3 B/L= 7 to 8 mm and M/D= 5 to 6 mm. The extracted teeth were mounted in acrylic resin blocks with the coronal portion of the tooth remaining above the acrylic block. Test specimens were placed into a special jig with a custom vise grip that was tightened around the coronal portion of the tooth. Torsional force was measured in the clockwise direction using a Lebow 1102-200 torque apparatus (with a maximum torque value of 200 inch X ounce) and the force was

recorded with a Hewlett Packard 7915B X-Y recorder. The torsional resistance values (inch X ounce) were: group 1; 33.97 + 9.20 (B/L = 5 mm, M/D = 3 -4 mm), group 2; 37.67 + 17.68 (B/L = 6 mm, M/D = 4-5 mm) and group 3; 76.15 + 33.71 (B/L = 7-8 mm, M/D = 5-6 mm). A one-way ANOVA and SNK (Student-Newman-Keuls) revealed that group 3 had significantly greater resistance to torsional loading than groups 1 and 2 (P < 0.0004). Groups 1 and 2 were statistically similar to each other. The tooth dimensions have an effect on torsional resistance of the tooth. The torsional resistance of teeth with B/L = 7-8 mm and M/D = 5-6 mm are significantly greater than the torsional resistance of teeth with B/L = 5-6 mm and M/D = 3-5 mm. The results of this study may be used as a threshold for assessing the suitability of an endodontic restorative component such as, a endodontic post, core, bonding agent and crown reconstruction. The torsional results in this study were in the same range as previous studies concerning in vitro torsional properties of post-core components. The torsional data obtained in this study can be used to predict a restorative components clinical behavior. Musikant BL, Cohen BI, Deutsch AS. The Relationship of Post Design to the Long-Term Success of Endodontically Restored Teeth. Compendium 2001;22(11):974-988. Artificial cores replace missing tooth structure and contribute to the retention and stability of the subsequent restoration. The post is the anchoring mechanism for the core, which supports the final restoration. Stability of the post and core is the most important factor concerning the long-term success of the entire restoration. The amount of insertional and functional stresses produced and distributed by a post are also an important factor in long-term success. An optimal way of maximizing retention, minimizing insertional stresses, and distributing functional stresses is through the use of a multi-tiered parallel threaded split-shank Flexi-Post/Flexi-Flange post systems. Cohen BI. Core Buildups and Restorative Considerations. Endodontic Therapy 2001;1(1):25. This article reviews the restorative process after the endodontic phase of treatment. The use of a bonding agent and specific post head designs, such as Flexi-Post and Flexi-Flange, have demonstrated maximum core material retention. The Flexi-Post/Flexi-Flange post systems also result in maximum retention in the root with excellent fatigue characteristics. Contemporary composite core materials, such as Ti-Core and Ti-Core Natural, which provide long-term fluoride release and exhibit strong dentinal


characteristics are preferable for a successful restoration. Cohen BI, Musikant BL, Deutsch AS. Wklady koronowo-korzeniowe systemu Flexi-Flange i ich zastosowanie kliniczne. Compendium Stomatolgii 2001;2:23-25. (Published in Polish: The Flexi-Flange post system and its clinical usage.) The clinical case below, reports on the use of No. 2 Flexi-Flange posts to restore a first premolar and canine. The unique design of the Flexi-Flange includes a parallel threaded primary shank that is split along its longitudinal axis, a second tier for close adaptation of the post to the root at the point where coronal flares often exist and a wider third tier that fits within a machined root faced area. The result of a Flexi-Flange post is a post with a large metal to dentin interface without the need of a wide taper. The advantages of a tiered system over a tapered system include significantly less lateral stresses during insertion and function. The Flexi-Flange system offers; high retention of the post in the root, superior distribution of stresses under insertion and under function, and long term resistance to metal fatigue. Sábio S, Mondelli J, Bonachela V, and Sábio SS. A comparative study of the fracture resistance of endodontically treated teeth between metal cast post and two resin-reinforced pré-fabricated system in the intraradicular restoration. J Dent Res 2002;81(Abstract 0324):A-67. The purpose of this in vitro study was to investigate the fracture resistance of endodontically treated roots after restoration with pre-fabricated system against root restored with metal cast post-core. thirty two maxillary canine with similar anatomic characteristic were sectioned to obtain the same length for all specimens. Group I consisted of 8 roots restored with FibreKor system. Group II consisted of 8 roots restored with C-Post system. Group III consisted of 8 roots restored with metal cast post-core, the diameter was similar FibreKor system. Group IV consisted of 8 roots restored with metal cast post-core, the diameter was similar C-Post system. Specimens were cemented with dual-cure bonding agent (Dual-Cement and Unibond). These roots were then mounted in acrylic blocks. Prepared specimens were stored in deionized water at 37°C for 24 hours before testing. The sample were tested in a universal testing machine (Kratos). Each sample was angled at 135 degrees to the long axis of the root. A constantly increasing force was applied until the root fracture. Results: The means (kgf) and standard deviations found for groups were: I – 31,01(2,08); II – 41,32(3,44); III – 49,17(2,09); IV – 47,65(2,94). The present research indicated that root restored with metal post was statistically significant (p<0.05) more

resistant to fracture over root restored with non metal post. The Ratings � � � � Reality Publishing Co. 2002:16:551. Flexi-Post and Flexi-Flange are unique, parallel-sided, muli-tiered, posts with a tapered end that has a split in it to redirect stresses into the post, not the root. The post head is serrated for maximum retention of core build-up material. These posts provide the ultimate in retention. Flexi-Post and Flexi-Flange received a four star rating. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retencja materialu odbudowujacego zrab koronowy zastosowanego z trzema róznymi wkladami koronowo-korzeniowymi. Stomatologia Wspólczesna 2001;8(6):57-61. (Published in Poland: Retention of a core material supported by three post head designs) The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS’ AccessPost and Flexi-Post


dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Musikant BL, Deutsch AS, Cohen BI. Estetyka w stosowaniu wkladów koronowo-korzeniowych. Compendium Stomatologii 2001;3:32-33. (Published in Polish) This article demonstrates the characteristics of the patented split-shank Flexi-Post / Flexi-Flange post systems. These patented split-shank posts are shown to have minimal insertional and functional stress while far surpassing the retentive properties of other post systems. These posts systems, coupled with Flexi-Flow Natural and Ti-Core Natural fluoridated composite cement and core build-up material have been shown to provide a lasting aesthetic restoration. Musikant BL, Cohen BI, Deutsch AS. The Metallic Versus the Nonmetallic Restored Dentition. Dent Today 2002;21(2):124-129. This article discusses the current trend in aesthetic nonmetallic post restorations, pointing out many concerns of use. Such shortcoming include inadequate stiffness, support, core material retention and retention in the root. The overall restoration should not be compromised by aesthetics. To achieve aesthetic restorations with the greatest possibility of long-term success a highly retentive metal post such as the Flexi-Post / Flexi-Flange system, coupled with porcelain fused-to-metal crowns may be used. Restoring a tooth with little or no coronal dentin using the Flexi-Flange post system. Dent Products Report 2002;36(6):50. This article outlines a clinical procedure in which the step-by-step utilization of the Flexi-Flange post system and Ti-Core Natural, fluoride releasing, composite core material was used to produce an aesthetic restoration in a clinical case with no coronal dentin. Cohen BI, Penugonda B, Singh CJ, Isidro MA. Fractural Strength of Post and Core/Crown Combinations-An In Vitro Study. Oral Health 2002;92(10):49-58. The purpose of this in vitro study was to compare the effects of two post designs (Flexi-Post and Vlock) in combination with two restorative core materials (silver amalgam (Tytin) and a titanium reinforced

composite resin (Ti-Core)) with a metal crown. In vitro fracture loading testing has been a common method of testing a post-core combination. However, there have been limited studies investigating the effects of a crown on the fracture strength of a prefabricated post and core. This in vitro study consisted of the preparation of 32 tooth/post and core/crown specimens. The specimens were divided into 4 groups and separated according to post and core material used. Metal cast crowns Midas gold (Au)-palladium (Pd) alloy were fabricated for each tooth/post and core combination. Each tooth/post and core/crown combination was placed in a special jig on a 45 degree angle on the buccal/lingual axis and subjected to a load on a universal testing machine (MTS Systems Corp) with a crosshead speed of 0.25 in/min (0.635 cm/min). The values for fractural strength for each group were: group 1 = Vlock/Ti-Core 140.8 + 63.6 pounds; group 2 = Flexi-Post/Ti-Core 137.0 + 59.3 pounds; group 3 = Vlock/Tytin 74.1 + 30.0 pounds; and group 4 = Flexi-Post/Tytin 138.8 + 39.7 pounds. A 2 X 2 factorial two-way analysis of variance (ANOVA) was used to test effects of core material and post type on fracture resistance. All results were considered statistically significant if p < 0.05. Group 3 had statistically lower fractural resistance than groups 1-2 and 4. Groups 1-2 and 4 were all similar to one another. The results for this study were in the same range as other in vitro studies where post and core/crowns were tested for fractural strength. Musikant BL, Cohen BI, Deutsch AS. Zasady osadzania i doboru rodzaju wkladu koronowo-korzeniowych: Jak przedluzyc zywotnosc wykonaego uzupelnienia? Magazyn Stomatologicznym. 2002;6:50-52. (Original Article published in Poland: Principles of Post Placement and Design: Prolonging the Life of Your Restoration.) This article outlines the principles of post placement and the superior post design of the Flexi-Post and Flexi-Flange post systems. These systems were found to have a high modulus of elasticity, superior retention, and minimal insertional stresses while distributing functional stresses evenly over the length of the shank in the root. Drummond JL, Bapna MS. Static and Cyclic Loading of Fiber-Reinforced Dental Resin. Dent Materials 2003;19:226-231. The aim of this study was to evaluate the flexure strength of unidirectional fiber-reinforced resins under static an cyclic loading with and without thermal cycling. The fiber-reinforced resin materials chosen for this project were commercially available endodontic posts and commercially procured bar samples. For all materials, controls for flexure strength were tested in air and in water using three-


point loading. Specimens were thermal cycled between 7 and 63º for 6000 cycles. A staircase approach was used to determine the flexure fatigue limit and scanning microscopy was used to examine the microstructure. Thermal cycling caused a significant lowering (11-24%) of the flexure strength for each resin based post system. The decreases in the strength property due to thermal cycling and the cyclic loading of these materials indicates that their utilization in the oral environment enhances their degradation, and potentially shortens their clinical life. Bapanaiah Penugonda, Brett I. Cohen, and Chandan J. Singh. Fractural Strength for Post and Core/Crown Combinations. J Dent Res 82 (Special Issue B (Goteborg Abstracts)):Abstract #2671,2003. Objective: This in vitro study was to test and compare the effects of two post designs (Flexi-Post and Vlock) in combination with two restorative core materials (silver amalgam (Tytin) and a titanium reinforced composite resin (Ti-Core)) with a metal crown. In vitro fracture loading testing has been a common method of testing a post-core combination. However, there have been limited studies investigating the effects of a crown on the fracture strength of a prefabricated post and core. Methods: This in vitro study consisted of the preparation of 32 tooth/post and core/crown specimens. The specimens were divided into 4 groups and separated according to post and core material used. Metal cast crowns Midas gold (Au)-palladium (Pd) alloy were fabricated for each tooth/post and core combination. Each tooth/post and core/crown combination was placed in a special jig on a 45 degree angle on the buccal/lingual axis and subjected to a load on a universal testing machine (MTS Systems Corp) with a crosshead speed of 0.25 in/min (0.635 cm/min). Results: The values for fractural strength for each group were: group 1 = Vlock/Ti-Core 140.8 ± 63.6 pounds; group 2 = Flexi-Post/Ti-Core 137.0 ± 59.3 pounds; group 3 = Vlock/Tytin 74.1 ± 30.0 pounds; and group 4 = Flexi-Post/Tytin 138.8 ± 39.7 pounds. A 2 X 2 factorial two-way analysis of variance (ANOVA) was used to test effects of core material and post type on fracture resistance. All results were considered statistically significant if p < 0.05. Group 3 had statistically lower fractural resistance than groups 1-2 and 4. Groups 1-2 and 4 were all similar to one another. Conclusions: The results for this study were in the same range as other in vitro studies where post and core/crowns were tested for fractural strength. Newman MP, Yaman P, Dennison J, Rafter M, Billy E. Fracture resistance of endodontically treated teeth restored with composite posts. J Prosthet Dent 2003;89:360-367.

The purpose of this study was to compare the effect of 3 fiber-reinforced composite post systems on the fracture resistance and mode of failure of endodontically treated teeth. Ninety maxillary central incisors were divided into 8 experimental groups and 1 stainless steel control group of 10 specimens each. Eighty teeth were assigned to 2 main experimental groups called “narrow” and “flared” canals. For the narrow canal group, post spaces were prepared with the corresponding diameter, respectively. For the flared canals group thin-walled canals were simulated. Teeth for the flared canals were restored with the same post but were cemented into tapered 2 mm wide canals created with a tapered diamond bur. Specimens were loaded to failure with a universal testing machine at a crosshead speed of 0.05 cm/min until failure occurred. The data was analyzed with analysis of variance and Student t tests (P<0.05). For the narrow canal, the mean load ranged form a low of 4.55 (±1.49)kg for the Ribbond standard to a high of 12.9 (±1.64)kg for the Luscent anchors. The stainless steel control group had the highest load value (18.33 (±3.27)kg. For the flared canal the low mean was 9.04 (±1.76)kg for FibreKor and the high was equal for both Luscent anchors and Ribbond standard, 12.87 (±2.69) and 12.87 (±3.54), respectively. The results from the study show that the load to failure of the stainless steel posts were significantly stronger than all the composite post studied. Musikant BL, Cohen BI, Deutsch AS. Post Design and the Optimally Restored Endodontically Treated Tooth. Compendium 2003;24:788-794. The basics for the sound restoration of endodontically treated teeth have not changed despite the advent of new materials and techniques. Adequate retention for posts and crowns, resistance to cyclic shearing forces, minimal insertional stresses, and even distribution of functional stresses are prime requirements that cannot be compromised without jeopardizing the longevity of the final restoration. Musikant BL, Deutsch AS. Post Design and its Impact on the Root and Crown. Compendium 2006;27:130-133. To optimize the longevity of an overlying restoration, it is important to follow proper engineering principles. These include the requirement of either an internal or external ferrule. When sufficient tooth structure does not exist to support an internal ferrule, it becomes necessary to use a porcelain-fused-to metal restoration. The posts supporting these restorations should have low insertional stress, high retentive values, and even distribution of functional stress. In the author’s opinion, the split-shanked design of the Flexi-Post and Flexi-Flange is the only design that can deliver this essential combination. The purpose of a post is to help restore or reinforce the coronal structure of a tooth to further increase the


retention and stability of an artificial crown. Removing tooth structure to place a post does not increase the root’s resistance to vertical or horizontal fracture. Smarge P, Sohn J, Ozcan M, Negriz I. Effect of surface treatment of titanium posts on the tensile bond strength. Dental Materials 2006;22:189-194. The purpose of this investigation was to investigate the effect of two conditioning treatments on the tensile bond strength of four resin-based luting cements and zinc phosphate cement to titanium posts. The composite resin luting cements did not show significant differences (P<0.05)showing values between (352±76 n-475±104 N) when the posts were air-abraded. Afterica silica coating and silanization, significantly higher (P<0.05) tensile strengths were obtained for Compolute® Aplicap (600±123 N) than those of the other lutic cements (Flexi-Flow cem TM:191±62 N; Panavia® 21 EX:375±77; Twinlook; 430±78 N). No significant differences (P>0.05) were found between the tensile strength of the posts luted with zinc phosphate (414±102 N) and the resin composite cements. Silica coating and silanization revealed the highest tensile bond strength in posts luted with Compolute® Aplicap but it was not effective for the other experimental groups. Zinc phosphate cement exhibited tensile bond strength as good as resin composite cements. Musikant BL, Deutsch AS. Post Design and Its Impact on the Root and Crown. Compendium 2006;27:130-133. To optimize the longevity of an overlying restoration, it is important ot follow proper engineering principles. These include the requirement of either an internal or external ferrule. When sufficient tooth structure dose not exist to support an internal ferrule, it becomes necessary to use a porcelain-fused-to-metal restoration. The posts supporting these restorations should have low insertional stresses, high retentive values, and an even distribution of functional stresses. In the author’s opinion, the split-shanked design of the Flexi-Post and Flexi-Flange is the only design that can deliver this combination. The purpose of a post is to help restore or reinforce the coronal structure of a tooth to further increasethe retention and stability of an artificial crown. Removing tooth structure to place a post dose not increase the root’s resistance to vertical or horizontal fracture. Yaman SD, Karacaer O, Sahin M. Stress Distribution of Post-Core Applications in Maxillary Central Incisors. Journal of Biomaterials Applications 2004;18:163-177. The purpose of this study was to evaluate the stress distribution in a maxillary central incisor restored with various post-core applications. The Study used

a three-dimensional finite element method. The tooth was assumed to be endodontically treated with a porcelain crown. Two different sizes of Flexi-post, Cear-post and Composipost were compared for 200N palatal and incisal loads. It was determined that, purely from the point of view of strength considerations, core material was determined to be of greater importance than post material or size. Higher elastic moduli of the posts resulted in lower stresses throughout the tooth. Gu S, Isidro M, Deutsch AS, Musikant BL. Comparison of the Retentionof 5 Core Materials Supported by a Dental Post. Int J Prosthodont 2006;19:183-184. Purpose: This study evaluated the retention of dental post heads (No.2 Flexi-Post) embedded in 5 core materials (1 auto mix resin composite, 2 hand-mixed resin composites, and 2 glass ionomers). Materials and Methods: Samples were prepaired by embedding post heads in 4.5-mm-thick disks of core material. Results: The resin composite materials provided significantly more retention than the glass-ionomer-based materials. The post head retention of the outo mix resin composite was comparable to that of the hand-mixed resin composites. Conclusion: Unlike the resin composite samples, all the glass-ionomer samles fractured during testing. This is an unacceptable condition for a clinically sussessful restoration. Schmage P, Sohn J, Nergiz I, Ozcan M, Various conditioning methods for root canals influencing the tensile strength of titanium posts. Journal of Oral Rehabilitation 2004;31:890-4. Sumary: Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, manufactures’ instructions for this purpose differ widely from one another. The Aim of this study was to compare the tensile bond strengths of passive, tapered, titanium root posts that were luted with four different resin composite cements (Compolute® Aplicap, Flexi-Flow cem™, Panavia® 21 EX, Twinlook®) in the root canals at three conditions, namely (i) no conditioning, (ii) etching with 37% phosphoric acid, and (iii) etching + bonding agent application. Panavia 21 EX was further tested after using the primer for the post-surface according to the manufacturer’s recommendations. The posts luted with zinc phosphate cement (Tenet) acted as the control group. Following endodontic preparation of 140 intact anterior teeth with hand instruments, the post-spaces were prepared using the opening drills of the corresponding size of the posts. The samples were first stored in water at 37º C for 24 h and then thermocycled (5000 cycles, 5-55 ºC, 30s). The tensile strength values were measured with the universal


testing machine at a cross head speed of 0·5mm min¯1. The data were analysed statistically using ANOVA and corrected with Scheffe test due to the significance levels )P<0·05). The Tensile bond strengths of the titanium posts after luting with various cements and thermocycling were affected by the conditioning systems used for the root canals. Tensile bond strengths were the higest with Flexi-Flow (475±78 N) followed in descending order by Panavia 21 EX (422±97N), Twinlook (430±78N) and Compolute Aplicap (352±76 N) after conditioning the root canal. The primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia 21 EX group (375±77 N) followed in descending order by Panavia 21 EX (442±97N), Twinlook (439±78 N) and Compolute Aplicap (352±76 N) after conditioning the root canal. The use of primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia group EX group (375±77 N) (P<0·001). Tensile bond strengths obtained after looting the posts with zinc phosphate cement (414±102N) wre nog significantly different (P<0·05) than those of resin composite cements. Although the importance of conditioning the root canal was evident for Panavia 21 EX, it was not the case for the other luting cements tested. Yaman, SD, Karacaer O, Sahin, M Stress Distribution of Post-Core Applications in Maxillary Central Incisors Journal of Biomaterials Applications Volume 18-January 2004 Abstract: The purpose of this study was to evaluate the stress distribution in a maxillary central incisor restored with various post-core applications. The study used a three-dimensional finite element method. The tooth was assumed to be endodontically treated with a porcelain crown. Two different sizes of a Flexi-Post, Cera-Post and Composipost were compared for 200 N palatal and incisal loads. It was determined that, purely from the point of view of strength considerations, core material was determined to be of greater importance than post material of size. Higher elastic moduli of the posts resulted in lower stresses throughout the tooth. Thesis by: Salah Abdel – Azeem Youseif Nasr Effect of ferrule length on fracture resistance of teeth restored with two different posts cemented with two types of luting materials. Within the limitation of this in vitro study the following conclusions may be drawn:

1. The fracture resistance of endodentically treated teeth increased with increasing the coronal dentinal structure (Ferrule length). 2. The fracture resistance of endodentically treated teeth restored by flexi post cemented with composite resin was higher than others

cemented with zinc phosphate. 3. The fracture resistance of endodentically treated teeth restored with cast post and cemented with composite resin was higher than cast post cemented with zinc phosphate. 4. The fracture resistance of endodentically treated restored with flexi-post and Ti core was higher than cast post and its core.

Gu S, Rasimick BJ, Deutsch AS, Musikant, BL In Vitro Evaluation of Five Core Materials J Prosthodont 2007;16:25-30 Purpose: This invitro study determined the fracture strength of five core materials supported by two different endodontic dowels. Diametral tensile strength and microhardness of three resin composite core materials used in this study were also tested. Material and Methods: The fracture strength study used one lanthanide-reinforced flowable resin composite (Ti-Core Auto E), one titanium- and lanthanide-reinforced composite (Ti-Core), one lanthanide-reinforced composite (Ti-Core Natural), and two metal-reinforced glass ionomer core materials (Ketac Silver and GC Miracle Mix). Two types of dowels were used: a multitiered, split-shank threaded dowel with a flange (#1 Flexi-Flange) and one without a flange design (#1 Flexi-Post). The specimens were divided into ten groups. Each tooth/dowel and core specimen was placed in a special jig at 45º and subjected to a load by a universal testing machine. The diametral tensile strength and the michrohardness of the three resin composite core materials were measured by a universal testing machine and Barcol hardness tester, respectively. All test groups contained ten specimens. Results: The fracture strength value of the resin composite core materials was significantly larger (p< 0.0001) than those for the metal-reinforced glass-iionomer core materials. Analysis of variance (ANOVA) also showed that the Flexi-Flange dowel interacted with Ti-Core and Ti-Core Auto E to significantly (p < 0.0013) increased the fracture strength relative to the Flexi-Post. One-way ANOVA revealed that there were no significant differences between them in terms of diametral tensile strength. The Barcol hardness values of the composite core materials were statistically different (p , 0.0001), with the Ti-Core the highest, followed by Ti-Core Natural, Then Ti-Core Auto E. Conclusions: Resin composite core material performed better than glass ionomer material in this in vitro study. The flowable composite core material performed about the same in terms of fracture strength and diametral tensile strength compared with nonflowable composites. Combined with certain core materials, the flange design increased the


fracture strength of the tooth/dowel and core combination. Rasimick BJ, Gu S, Deutsch AS, Musikant BL Measuring the Radiopacity of Luting Cements, Posts, and Core Build-up Materials with a Digital Radiography System Using a CCD Sensor J Prostodont 2007;1-8 Purpose: This study assessed the radiopacity of five luting cements, five posts, and five core build-up materials using two target distances. Material and Methods: Materials were analyzed using a modified version of ISO protocol 4049. 1-mm thick samples were digitally radiographed alongside a stepwedge fo aluminum alloy 1100 using a Trophy RVG-4 CCD sensor and 70 kVp X-ray generator. The gray-scale values of the stepwedge and sample were converted to X-ray absorbencies. The relationship between X-ray absorbance and aluminum thichness was linear for thickness and less than 10 mm and followed a power-law relationship above 10 mm. These relations were used to convert the absorbencies of the samples into aluminum thicknesses. The radiopacity data was subjected to ANOVA/Student-Newman-Keuls testing. Results: All materials were more radiopaque than equivalent thicknesses of aluminum. Each product category contained a wide range of radiopacities. Syringe-dispensed materials tend to be less radiopaque than materials dispensed by mechanically assisted syringe or mixed by hand (p < 0.01). Target distance did not affect the measured radiopacity so long as the exposure time was suitably adjusted (p = 0.86). Conclusions: All luting cements and core materials met or exceeded the ISO minimums. The tested metal-reinforced glass ionomer core build-up materials were extremely radiopaque. Some publications suggest that excessively radiopaque core materials can hinder a clinician’s ability to spot voids or marginal defects. Rasimick BJ, Shah RP, Musikant BL, Deutsch AS Effect of EDTA conditioning upon the retention of fibre posts luted with resin cements International Endodontic Journal,41,1101-1106 Aim: To determine if a final rinse with EDTA improves the short-term in-tooth retentive strength of adhesively luted fibre-reinforced composite posts. Methodology: Six different commercial fibre post systems were tested. Post spaces in extracted human anterior teeth were irrigated with either 6% NaOCl or 6% NaOCl followed by 17% EDTA. Posts were luted using the manufacturer’s recommended bonding agent and luting cement. Two different sizes of posts were tested for each post system. After 24 h of storage, the retentive strength of the post to tooth (14 per group, 336 total) was tested using a pull-out technique. Three-way ANOVA and the Student-Newman-Kuels test were used to test the effects of

irrigation regimen, post size and post brand on the retentive strength of the fibre post. Results: Almost every sample failed at the interface between dentine and luting cement. Irrigation method did not have any signivicant effect (P > 0.14) for any group other than the ParaPost Fibre White (P < 0.001). The overall retention of a post appeared to be correlated to the amount of surface texture on the post; the smooth ICEPost was the least retentive brand, the textured FibreKor and the ParaPost Fibre White posts were moderately retained, and the threaded Flexi-Post Fibre and the Flexi-Flange Fibre psots were the most retentive brands tested. For all brands, larger diameter posts were more retentive than smaller diameter posts (P < 0.008). Conclusions: A final rinse of EDTA did not improve the short-term retention of fibre posts except for ParaPost Fibre White.

FLEXI-OVERDENTURE®, EDS’ ACCESSPOST™ OVERDENTURE 2/1 & EZ-CHANGE ®

FLEXI-OVERDENTURE® & EDS’ ACCESSPOST™ OVERDENTURE ATTACHMENT WITH THE EZ-CHANGE® ATTACHMENT The key component of the patented Flexi- Overdenture Attachment kit is the patented split-shank Flexi-Post. It absorbs the stresses of insertion by gradually closing during placement yet it provides maximum retention. EDS’ AccessPost Overdenture Attachment is based on the patented EDS AccessPost system, this parallel sided, passive overdenture post provides easy post removal and access to the apex in the event of a failed root canal. The Overdenture Attachment is constructed as a ball and socket, with the (male) ball located on the coronal end of the post. The (female) socket is made of nylon and is easily incorporated into the denture. The Flexi or EDS AccessPost Overdenture Attachment enormously enhances denture retention. The EZ-Change patented attachment system is a major step forward in overdenture ease of use. This new keeper and cap insert system was designed to drastically reduce the time involved in replacing a worn cap insert due to the oral environment. Replacement now takes seconds, where before it took 30 minutes of chair time. The patented EZ-Change® Implant Overdenture Abutment Attachment utilizes the before mentioned EZ-Change attachment systems along with a corresponding implant overdenture abutment to provide an easy technique producing quick, easy, economical results completely at chairside. The EZ-Change® Implant Overdenture Abutment Attachment fits todays popular implant systems. Musikant BL, Deutsch AS. Endodontic posts and cores, part three - Clinical use of Flexi-Post. J Alabama Dent 1985;70:22-28. The Flexi-Post system procedure for endodontic root canal treatment is described, where primary reamer and secondary drill is used to prepare a post-hole in the root of the tooth. The ideal way the Flexi-Post should fit includes an intimate contact between the second tier of the post and the coronal flare of the root canal. The Flexi-Post system assures minimum stress during both insertion and function. Composite resin cements are recommended when seating most Flexi-Post because these cements have a higher crushing strength than either zinc phosphate or glass ionomer cements. Cores may be formed with either composite resin, glass ionomer cement or silver amalgam.

Also described is the Flexi-Overdenture Attachment, as used to secure a full denture prosthesis to residual roots. It was cemented with glass ionomer cement. In this case, glass ionomer was recommended because it offers fluoride release when the cement is in continuous contact with saliva. Binder J, Deutsch AS, Musikant BL. The New Flexi-Post Overdenture Attachment. General Dentistry. 1986;362-363. The Flexi-Overdenture Attachment is described. The post portion of the attachment was found to offer high retention and ease of insertion, with lack of root stress. The caps for the overdenture attachment are supposed to last 1.5 to 2 years before replacement. This is borne out by a case where a patient was monitored 1.5 years after treatment. The clinical report for this patient was also documented by a complete procedure including photographs. Elkins WE. Keeping it simple-An Overdenture Technique. ODA Journal 1986:15-17. A sixty-two year old female is the subject of this case report where the Flexi- Overdenture Attachment was used. After fitting the post, it was cemented with glass ionomer cement. Then the female keeper was snapped into each post. Cold-cured acrylic was mixed and placed into the clasp network and positioned in the mouth. The partial was then removed from the mouth and finished as usual. Dummer PHM, Edmunds DH, Gidden JR. Root canal retained restorations; 3. Root-faced attachments. Restorative Dentistry. 1990;17:335-339. This article describes some root-faced attachments, as well as a number of prefabricated post systems, with integral overdenture attachments. Root canal retained attachments are made up of two groups: 1) prefabricated, threaded with integral attachments (Flexi-Overdenture, Dalbo-Rotex and Kurer K4 Denture-Anchor), and 2) cast nonthreaded with custom-made diaphragms and precision anchors (ParaPost & Materpost). The prefabricated post system (Flexi-Overdenture), with an integral attachment, is threaded with a split shank design. It exhibited a simple technique, as compared to the custom-made posts (cast-post) with diaphragms and precision anchors, at a reduced cost. Leung T, Preiskel HW. Retention profiles of stud-type precision attachments. International Journal of Prosthod 1991;4:175-179. The retention of 12 commercially available stud-type attachments, suitable for use with overdentures were


studied. The vertical distances relating to the resistance for separation, the studs' configuration and design, were compared for all of the systems. The maximum forces (retention) recorded during separation of the attachment units (from largest to smallest) were as follows: Flexi-Overdenture (16N, 3.58 lbs)> Dalbo Rotex (12N, 2.68 lbs)> Conod (9N, 2.0 lbs)> Microfix (8N, 1.79 lbs), Gerber Cylinder (8N, 1.79 lbs), Zet Anchor (8N, 1.79), ERA (grey Patrix) (8N, 1.79 lbs)> Dalbo Cylinder (7N, 1.57 lbs)> Axial Ceka Revax (6N, 1.34 lbs)> Rothermann Eccentric (5.5N, 1.23 lbs)> Era (white Patrix) (4.8N, 1.07 lbs)> Baer & Fah (3N, 0.67 lbs). The Flexi-Post system resulted in the largest force for separation (of the overdenture attachment used), while demonstrating the best design and configuration. Cohen BI, Pagnillo M, Condos S, Deutsch AS, Musikant BL. Comparative study of two precision overdenture attachment designs. J Prosthet Dent 1996;76(2):145-152. This study consisted of two different precision overdenture attachment designs which were tested for retention; 1) a nylon overdenture cap system and 2) a new cap and keeper system. This new cap and keeper system was designed to drastically reduce the time involved in replacing a worn cap due to the oral environment. This study consisted of six groups tested at two different angles. Retentive failure was studied at two different angles (26º and 0º) and failure was measured in pounds with a force gauge over a 2000 pull cycle. The two dependent variables were absolute force (AF) and relative force (RF). Repeated measures analysis of variance (RMANOVA) was used to compare the "between subjects" effects of cap and angle, and the "within subjects" effects of pull. There was significant difference between cap types (p<0.0001) with respect to the RF required to remove the cap. There was no effect of angle. For AF, RMANOVA revealed a highly significant interaction between pull and cap (p<0.0001), meaning that the way that force changed over pulls depended on which cap was being used. There was no effect of angle. For relative force (RF), RMANOVA showed no interaction between pull and cap. There was a main effect of cap type (p<0.0001). There was no effect of angle. The nylon cap design required less force for removal, but showed more consistency in the force required over the course of the 2000 pulls as compared to the keeper with cap insert. The results obtained in this study were consistent with similar studies in literature. Epstein DD. A Potpourri of Overdenture Stud Attachment Systems. Dentistry Today 1995;May:84-89.

This discussion will be limited solely to the overdenture anchors that can be attached to bare retained root, the simplest procedure available for creating an overdenture (although some of the anchors discussed here are also available placed with an implant fixture). There are a number of attachment systems, such as the Flexi-Overdenture, the ERA, the ORS direct, the Dalbo-Rotex and Magnet systems. The Flexi-Post Post-Core System has always shown to be an effective and working system. The Flexi-Overdenture Attachment is similar. It is a stainless steel, supra-radicular male that is imbedded and cemented into the retained root, and a nylon female cap, which itself is luted into the under surface of the denture. This is necessarily a load bearing device. Musikant BL, Cohen BI, Deutsch AS. Replacement insert makes denture and post connection easier. Dentistry Today 1995;December:116-117. Like many restorations in dentistry, what fits so well initially may, depending on a patient's occlusion, deteriorate over time. The weak point in all overdenture systems is the connection between the denture and the post. They wear out and must be replaced. The Flexi-Overdenture system (Essential Dental Systems, So. Hackensack, NJ) is no different. However, an addition to the system, the EZ-Change Keeper and Cap Insert allows for replacement in less than one minute. What follows is a clinical describing the complete technique. The metal keeper is permanently cold cured into the denture. When replacement is needed, simply take the two pronged wrench provided with the kit and place it in the holes inside the cap insert and rotate out the old cap with a counterclockwise motion. Place the prongs of the wrench into the holes inside the new insert, line up the thread of the insert with that of the metal keeper and rotate in with a clockwise motion. You will feel a tactile click when the cap is fully inserted. Replacement is complete within about 30 seconds chair time, and there is no need for cold curing. Musikant BL, Cohen BI, Pagnillo M, Condos S, Deutsch AS. Comparison of the Retention of Two Precision Attachment Overdenture Designs. Abstract J Dent Res 1996;75 IADR Abstract 321:59. This in vitro study compared how much retentive force was required to remove two different overdenture attachment designs for the Flexi-Overdenture Post System, over a 2,000 pull test configuration. This study consisted of two different precision overdenture attachment designs; 1) a nylon overdenture cap system and 2) a new inner cap and keeper system. This new cap and keeper system was designed to drastically reduce the time involved in replacing a worn cap due to the oral environment. This study consisted of four


groups tested at two different angles (26º and 0º) and failure was measured in pounds with a force gauge over a 2,000 pull cycle. Results ranged from retentive values of 1.5 pounds to 10 pounds. The two dependent variables were Absolute Force (AF) and Relative Force (RF). Repeated measure analysis of variance (RMANOVA) was used to compare the effects of the cap type and angle, and the effect of pull on type of cap. There was a significant difference if p<0.05. There was a significant difference between cap types (p<0.0001) with respect to the RF required to remove the cap. There was no effect of the angle. For Absolute Force (AF), RMANOVA revealed a highly significant interaction between pull and cap (p<0.0001), meaning that the way that force changed over pulls depended on which cap was being used. There was no effect of angle. For Relative Force (RF), RMANOVA showed no interaction between pull and cap. There was a main effect of cap type (p<0.0001). The nylon cap design required less force for removal, but showed more consistency in the force required over the course of the 2000 pulls as compared to the keeper with cap. The new cap and keeper design allows for good retention as compared to the nylon overdenture cap, and allows the dentist to replace worn caps easily in seconds. The angles of 26º and 0º which were tested had no effect on the force required to remove the caps. The results obtained in this study were consistent with similar studies in literature. MUDr. V. Zabrodsky, MUDr. R. Jirkalova. Korenove cepy Flexi-Post Ctyrlete zkusenosti s klinickym pouzitim prefabrikovanych korenovych cepu s rozpolcenou korenovou casti. Quintessenz 1996;5:62-66. This article was recently published in Quintessence International in the Czech Republic. The research investigated the retention and stability of the Flexi-Post, Flexi-Flange, Ti-Core and Flexi-Overdenture systems. All these systems were shown to have clinical advantages over commercially available systems. 1997 CRA Dental Buying Guide — Clinical Research Associates Newsletter 1997;2(1):2. The EZ-Change overdenture attachment system (Essential Dental Systems, Inc.) was highly rated after clinical field trials by CRA clinicians (100% Approval). Epstein, PL, Epstein, DD. Overdentures: A Review and Update. GP-The Journal of New York State Academy of General Dentistry 1997;Sept:14-15.

The Flexi-Overdenture: A stainless steel male on a screw-type, split-shank, flange post (to reduce internal stressed) in the root, with a nylon cap female is luted into the denture. Load bearing by nature, and limited, with rotational resiliency. This supraradicular system has excellent retention. The EDS AccessPost Overdenture provides a method for simplified endodontic retreatment should it be necessary. Pagnillo MK, Cohen BI, Epstein D, Epstein P. A Comparison of the Retentive Properties of Six Prefabricated Overdenture Systems. J Dent Research. (IADR Abstract #2917) 1999;78:470 The purpose of this in vitro study was to compared how much retentive force was required to remove six different prefabricated overdenture attachment designs over a 2,000 pull test configuration. This study consisted of six groups with 10 specimens per group; group 1)EDS’ AccessPost Overdenture/EZ-Change system, group 2) Flexi-Overdenture/ EZ-Change system, group 3) ERA/grey caps, group 4) ERA/white caps, group 5) OSO system, and group 6) ZAAG system. The pull resistance was measured in pounds with a force gauge (Shimpo Force Gauge) over a 2,000 pull cycle (pull 1, 10, 50, 100, 500, 1000, 1500, and 2000). Results ranged from 5.63 to 12.01 pounds for the first pulls to 1.45 to 2.73 pounds for the 2,000 pull (last pull). The two dependent variables were Absolute Force (AF) and Relative Force (RF). Repeated measures analysis of variance (RMANOVA) was used to compare the effects of post and pull. A standard one-way ANOVA was used to compare AF and RF at pull 2,000th, followed by a Student-Newman-Keuls (SNK) multiple comparisons test. There was a significant difference if p<0.05. Retention values for the first and last pull were as follows:

Pull

EDS AccessPost OVD

Flexi- OVD

OSO

ERA Grey

ERA White

ZAAG

1 8.68± 3.46 lbs

12.01± 3.61 lbs

5.63± 2.00lbs

12.00± 5.09 lbs

6.65± 1.51 lbs

6.22± 2.90 lbs

2,000

2.28± 1.85 lbs

1.88±0.77 lbs

2.73± 1.18lbs

1.45± 0.50 lbs

1.98±0.67 lbs

2.60± 0.87 lbs

For AF there was no significant difference between posts in mean force required on the 2,000th pull. However, there was a significant difference between posts (p<0.001) mean in the way AF changed over pulls. For Relative Force (RF), RMANOVA also

showed an interaction between pull number and post (p<0.0008). It was concluded from the results that there were three groupings: OSO and ZAAG systems which had the least rate of change and the lowest first pull retention, the ERA white and the EDS AccessPost


Overdenture having the middle rate of change, and the Flexi-Overdenture and ERA grey having the largest rate of change. The Flexi-Overdenture gave the highest retention value of 12.01 pounds for the first pull and OSO system gave the lowest retention value of 5.63 pounds for the first pull. The retention (AF) at the end of the 2000th pull configuration were statistically similar for all groups studied. Epstein DD, Epstein PL, Cohen BI, Pagnillo MK. A comparison of the retentive properties of six different overdenture attachment systems. J Prosthet Dent 1999;82:579-84. The in vitro retention measured in pounds, of six overdenture anchor attachment systems, EDS’ AccessPost Overdenture/EZ-Change, Flexi-Overdenture/EZ-Change, ERA white, and ERA Grey, O-SO and ZAAG were tested of a cycle of 2000 “pulls”. Records of the pounds of force necessary to separate each system were made at the beginning of the testing, at pull 10, and then at every 50th pull until the 2000th pull was attained. The pulls were all performed manually using a Shimpo Force Gauge. Absolute Force (AF) and Retentive Force (RF) were compared, AF being the force required at any pull to separate the overdenture device, while RF is the force required at any pull expressed as a percent of the force required at the first pull. There was considerable difference of the force required at pull 1 for the ERA white, O-SO and ZAAG anchor systems, then the EDS AccessPost Overdenture and finally the Flexi-Overdenture and ERA Grey. However, at pull 2000, there was no statistical difference between any of the attachments studied. The amount of force necessary to offer functional retention to a specific patient wearing an overdenture will vary considerably, depending first upon the many factors in fabricating the overdenture, and then the age, strength, musculature and even the expectations of the patient. Photoelastic stress patterns produced by implant-retained overdentures. Kenney R, Richards MW. J Prosthet Dent 1998:80(5):559-564. When 2 implants are used to support a removable overdenture, optimal stress distribution to minimize forces to the implants is desired. This study used photoelastic analysis to compare the stress patterns generated around implants with 2 retention mechanisms. Two root form implants were anchored in a photoelastic mandible and a removable oral mucosa. Attachment of the denture to the implants was varied by using ball/O-ring and bar-clip attachments. Vertical and oblique occlusal forces from 10 to 200 lb were applied unilaterally to the right and left first molars. Resultant stress distributions in the photoelastic

mandible were photographed and evaluated. Within the limits of this study, ball/O-ring attachments transferred less stress to implants than the bar-clip attachments when the photoelastic model was subjected to a posterior vertical load. When the clinician desires to optimize stress distribution and minimize forces to the implants, the ball/O-ring attachment may provide adequate retention while possibly reducing stress on the implant bodies. Implant Overdentures. Deutsch AS, Musikant BL, Cohen BI. Dent Today 1999;18(5):30-31. Research has been accumulating over the last 5 years pointing to a viable alternative to implant retained fixed bridgework. This alternative is implant retained overdentures that have some type of retentive attachment. Recently, Essential Dental Systems, has improved its Flexi-Overdenture attachment (a ball-and socket design proven to have the highest overdenture retention) and now offers it as an implant attachment. The EZ-Change Implant Overdenture Attachment consists of; a ball abutment, a nylon cap insert and a metal keeper. This article guides you through the simple technique even if you have not restored implant cases before to give your patient a restoration that looks well and functions even better. Implant Overdentures:Keeping it Simple! Deutsch AS, Musikant BL, Cohen BI. Implant News & Views 1999;1(3):3-11. Essential Dental Systems has improved its Flexi-Overdenture attachment (a ball-and socket design proven to have the highest overdenture retention) and now offers it as an implant attachment. The EZ-Change Implant Overdenture Attachment consists of; a ball abutment, a nylon cap insert and a metal keeper. This article guides you through the simple technique even if you have not restored implant cases before to give your patient a restoration that looks well and functions even better. Cohen BI, Pagnillo M, Condos S, Deutsch AS. Studium porównawcze dwóch. Przeglad Stomatologiczny 2000;January:27-29. (Published in Polish: Comparative study of two precision overdenture attachment designs.) This study consisted of two different precision overdenture attachment designs which were tested for retention; 1) a nylon overdenture cap system and 2) a new cap and keeper system. This new cap and keeper system was designed to drastically reduce the time involved in replacing a worn cap due to the oral environment. This study consisted of six groups tested at two different angles. Retentive failure was studied at two different angles (26º and 0º) and failure was measured in pounds with a force gauge over a 2000 pull


cycle. The two dependent variables were absolute force (AF) and relative force (RF). Repeated measures analysis of variance (RMANOVA) was used to compare the "between subjects" effects of cap and angle, and the "within subjects" effects of pull. There was significant difference between cap types (p<0.0001) with respect to the RF required to remove the cap. There was no effect of angle. For AF, RMANOVA revealed a highly significant interaction between pull and cap (p<0.0001), meaning that the way that force changed over pulls depended on which cap was being used. There was no effect of angle. For relative force (RF), RMANOVA showed no interaction between pull and cap. There was a main effect of cap type (p<0.0001). There was no effect of angle. The nylon cap design required less force for removal, but showed more consistency in the force required over the course of the 2000 pulls as compared to the keeper with cap insert. The results obtained in this study were consistent with similar studies in literature. Tech-Specs: A Ball and Socket EZ-Change Overdenture Attachment System for Implants. Contemporary Esthetics. 2001;5(7):70-72. The introduction of a new ball and socket device (EZ-Change) for implant overdenture cases maximizes retention while allowing rotation that minimizes stress to the ball, implant and surrounding bone. The EZ-Change Attachment System enhances the ball and socket device by allowing for the rapid and easy change of the nylon cap insert if and when it becomes necessary. The high retention and ease of use of the EZ-Change Attachment System give the patient and the dentist an affordable alternative to the much more expensive and complicated procedures of multiple implants and fixed bridgework. Dobies K, Minor M. Wklady koronowo-korzeniowe Flexi-Post stabilizatorami protez nakladowych typu overdenture. Magazyn Stomatologiczny 2002;5:8-11. (Original article publish in Poland) This study describes a simple method of increasing retention of overdentures by the use of the Flexi-Overdenture and EZ-Change systems.

REINFORCED COMPOSITES 3/1

REINFORCED COMPOSITES: TI-CORE® WITH TITANIUM, TI-CORE NATURAL AND TI-CORE AUTO E REINFORCED WITH LANTHANIDE FLEXI-FLOW CEM®, FLEXI-FLOW AUTO WITH TITANIUM FLEXI-FLOW NATURAL, FLEXI-FLOW AUTO E REINFORCED WITH LANTHANIDE Ti-Core and Flexi-Flow are the only titanium incorporated composite core and post cement materials. Ti-Core was developed by placing two different species of titanium within a Bis-GMA matrix. The result of this union are composite materials that approximates natural dentin in hardness. Both composites have sustained fluoride release and are radiopaque. Ti-Core Natural and Flexi-Flow Natural are lanthanide reinforced self curing composite materials with strength comparable to dentin. Ti-Core Natural and Flexi-Flow Natural have sustained fluoride release and are radiopaque. The materials are available in Vita® shade A3 for aesthetic restorations. Cohen BI, Deutsch AS, Musikant BL. Compressive strength of titanium reinforced composites. J Dent Res 1992;61:125. The purpose of this study was to determine the compressive strength of two titanium reinforced composites (Bis-GMA), comprising two different viscosities. The experiment was made up of four groups. Compressive loading was performed on a modified universal testing machine. The titanium reinforced post cement (Flexi-Flow Cem) and core build-up paste (Ti-Core) were measured to have compressive strengths of 41,875 and 41,131 psi, respectively. This compares to the non-titanium post cement and core build-up paste materials with compressive strengths of 29,534 and 33,500 psi, respectively. The addition of titanium resulted in a 42% increase in compressive strength for the core buildup material. Statistically, these increases are highly significant (p<0.005). Both titanium reinforced composites closely approach the compressive strength of dentin (43,100 psi). The Dental Advisor-Plus. 1992;2:3. Ti-Core ++++ (Essential Dental Systems, Inc., 89 Leuning St., S. Hackensack, NJ) Ti-Core is described as a titanium-reinforced, self-cured composite core material recommended for crown build-ups, blocked undercuts and emergency restorations of fractured posterior teeth. Positive features include: 1) easy to mix, 2) easy to syringe, and 3) fast set-up after placement. Ti-Core is also described as having excellent flow, making it adaptable to pins, posts, and undercuts, and useful for

cementing old crowns. Its high strength makes it less likely to be gauged during cutting and contouring of the core. Ti-Core can be used with dentin bonding agents to improve the bond between the core and the tooth. The Dental Advisor - Plus highly recommends Ti-Core as a posterior core build-up because of its high strength, good adaptability and flow. The Dental Advisor - Plus rated Ti-Core "very good," with "four pluses." Cohen BI, Condos S, Musikant BL, Deutsch AS (Essential Dental Laboratories, S. Hackensack, NJ USA). Dentin shear bond strengths: Titanium Composite vs. Glass ionomers. J Dent Res 1992;71:226. In vitro dentin shear bond strengths of an auto-cured titanium reinforced composite (Ti-Core)using two third generation dentin bonding agents (Tenure and Scotchbond 2) were compared to various formulations of glass ionomers (Ketac-Silver, GC Miracle Mix and Ketac-Cem). The experiment was divided into fifteen groups containing ten samples each; tested at three different times intervals (15 minutes, 24 hours and 7 days). Shear bond strength values were obtained on a universal testing apparatus. Data was recorded in pounds and the shear bond strengths were calculated and expressed in P.S.I. ANOVA two-way analysis of variance (p<0.0001) was obtained. The shear bond strength from largest to smallest (15 minutes, 24 hours, 7 days) was the following; Ti-Core with Tenure (914, 907, 995 P.S.I.) > Ti-Core with Scotchbond 2 (717, 602, 704 P.S.I.)> Ketac-Silver (352, 433, 379 P.S.I.), GC Miracle Mix (264, 338, 372 P.S.I.)> Ketac-Cem (196, 237, 156 P.S.I.). Statistically, there was no difference in the shear bond strength for all samples studied according to time. The shear bond strength for Ti-Core with tenure was 2.0 to 2.5 times larger as that found for the silver filled glass ionomers Ketac-Silver and GC Miracle Mix. Ti-Core with Tenure also had consistently higher shear bond strengths than Ti-Core with Scotchbond 2. These trends are similar to those found in literature. Knobloch L, Kerby RE (The Ohio State University College of Dentistry, Columbus, Ohio). Flexural strength of composite resin and glass ionomer core materials. J Dent Res 1992;71:245. The objective of this study was to compare the flexural strength of two composite resins (Prosthodent [PD] and Ti-Core [TI] and three glass ionomer (Ketac-Silver [KS], Miracle Mix [MM], and Core-Shade [CS] core filling materials at 1 and 24 hours. Rectangular shaped specimens (n=6) measuring 25 mm X 3 mm X 3 mm were prepared in machine tooled stainless steel split molds and maintained in distilled water at 37o + 2o C and then randomly tested on an MTS machine utilizing a three-point loading jig at a rate of 0.5 mm/min. Mean values with standard deviations are listed in the table below. Mean Flexural Strength in MPa (SD) Material 1 hour 24 hours


PD 85.9 (5.2) 106.8 (4.8) TI 65.9 (2.6) 75.9 (0.9) KS 12.0 (2.1) 28.4 (6.2) MM 18.1 (0.9) 24.5 (4.2) CS 12.4 (2.6) 23.5 (1.7) ANOVA (p<0.001) and Tukey's Studentized Multiple Range Test (0.05) indicated significant differences at both 1 and 24 hours. The composite resin core filling materials exhibited significantly higher flexural strengths than any of the glass ionomer based systems at both 1 and 24 hours. This study was supported by the Ohio State University College of Dentistry. Deutsch As, Cohen BI, Condos S, Musikant BL (Essential Dental Laboratories, S. Hackensack, NJ USA). Compressive and diametral tensile strength of titanium reinforced composite. J Dent Res 1992;71:246. This study determined the compressive and diametral tensile strength of two titanium reinforced composites (Ti-Core and Flexi-Flow cem with titanium) and compared their strengths to dentin, core materials and cements (Den-Mat Core paste, Ketac-Silver, GC Miracle Mix, Fleck's ZOP cement, Durelon, Ketac-Cem). Compressive and diametral tensile loading was performed on a universal testing apparatus. Values were recorded in pounds, calculated and expressed in P.S.I. Compressive strength values were: Ti-Core (41,131), Flexi-Flow (41,876), Den-Mat Core Paste (32,741), Ketac-Silver(16,697), GC Miracle Mix (14,197), ZOP (12,198), Durelon (9,152) and Ketac-Cem (9,142). Diametral tensile values were: Ti-Core (5,219), Flexi-Flow (4,930), Den-Mat Core Paste (4,694), Ketac-Silver (1,814), GC Miracle Mix (1,408), ZOP (901), Durelon (1,285) and Ketac-Cem (996). ANOVA one-way analysis of variance (p<0.0001) was obtained. The titanium reinforced composites were statistically stronger in compressive and tensile strength than Ketac-Silver, Fleck's ZOP cement, Durelon, Ketac-Cem, and GC Miracle Mix. Both titanium reinforced composites approach the compressive and diametral tensile strength of dentin (43,100) and 6,000 P.S.I.). Lattner MJ, Burgess JO, Robbins JW (University of Texas Health Science Center, San Antonio, TX). Fracture resistance of four pin-retained core materials. J Dent Res 1992;71:1572. Various materials have been used to provide a foundation for cast crowns. Although amalgam traditionally is used, composite resin and glass ionomer are also used as core materials. This project examined the fracture resistance of four commonly used materials. Extracted teeth were sized, ground with a model trimmer to 3 mm above the CEJ, and mounted in acrylic resin filled PVC tubes using a surveyor. Four Minim self-threading pins were placed in the teeth at the line angles using a template. The Ketac-Silver group had pins that extended 2 or 4 mm above the prepared tooth surface, the other groups used pins 2 mm long. The core materials were mixed according to the manufacturers'

directions and placed into compound supported matrices. All materials were allowed to set in water for 1 week. The specimens were placed into a fixture which held the teeth at 45 degrees and they were loaded in an Instron at a crosshead speed of 5mm/min until failure. Mean Failure loads (N=10) Failure Mode Ketac Silver (2mm pins) 660+(127) Material Cohesive Ketac Silver (4mm pins) 614+(114) Material Cohesive Tytin Amalgam 915+( 73) Combination-pin tooth, amalgam Fluorocore 1084+( 96)

Pins Sheared Ti-Core 1176+(117)

Pins Sheared Using an ANOVA and Tukey-B post-hoc comparison, significant intergroup differences were determined. All groups connected with a line are not significantly different from each other. Composite resin cores had significantly higher fracture resistance (p=0.01) which may result clinically in more durable crown foundations. Deutsch AS, Cohen BI, Achan DM, Condos S, Musikant BL, (Essential Dental Laboratories, S. Hackensack, NJ). Fracture resistance of three different post and core materials. J Den Res (IADR Abstracts), 1992;72:1195. The purpose of this study was to compare the fracture resistance of three different core materials (Ti-Core, Ketac-Silver and Tytin amalgam) with three different post systems (Flexi-Post (FP), Parapost (PP) and Vlock's post (V). Each post system comprises a different head design which includes; length, diameter, depth and pattern of grooves. The experiment was divided into nine separate groupings, with each group comprising ten samples each. Cores were constructed with the use of a supporting matrix and standardized to a height of 4.5 mm with the use of diamond burs. The specimens were placed into a fixture (jig) at a 45 degree angle. Fracture resistance values (measured in pounds) were obtained with the use of a modified testing machine. A 3x3 factorial two-way analysis of variance (ANOVA) (p<0.0408) was obtained to determine which conditions differed from one another. Strength values from largest to smallest were; V with Ti-Core 218.8, FP with Ti-Core 204.9> PP with Ti-Core 164.8, FP with Tytin 156.0 > PP with Tytin 134.6, V with Tytin 100.6> FP with Ketac-Silver 69.4, V with Ketac-Silver 50.4> and PP with Ketac-Silver 37.7. The titanium composite core material, Ti-Core, in all cases had the largest fracture resistance while the silver filled ionomer, Ketac-Silver had the smallest. The threaded, split-shank Flexi-Post and the microthread Vlock post had the largest fracture resistance values, while the passive post, Parapost, had the least. Both the Flexi-Post and the Vlock post have large bulky heads with many vertical and horizontal grooves; this, as a result, makes it possible for the core


material to lock into the post head more effectively than for the Parapost. Taleghani M, Bokmeyer T (Baylor College of Dentistry, Dallas, TX) Evaluation of titanium reinforced composite as a core build-up material. J Dent Res (IADR) 1992;72:1947. A high filler content composite under special conditions has been recommended as a core material under cast restorations. Composite core offers several advantages, including bonding, ease of manipulation and rapid setting time. Recently a reinforced composite with titanium filler (Ti-Core) has been introduced as a core material. It has been suggested that titanium filler adds strength and resilience to the composite. The purpose of this investigation was to determine the comparative abilities of Ti-Core and an auto cure composite (core paste) to the cast post core, to resist displacement or fracture under conditions designed to simulate occlusal loading. The Ti-Core is used with and without bonding agent. Forty extracted single rooted bicuspid teeth were employed. The crown of each tooth was removed. Four different build-up materials and techniques were used. Cast post and core, prefabricated post and Ti-Core, with bonding agent and prefabricated post and core-paste. A full cast crown was constructed for each specimen. All teeth were mounted into the test bracket with acrylic resin. An Instron testing machine was used to apply controlled loads to the buccal cusp of each tooth. The average force required to cause failure of the restorations were as follows: cast post core 244 lbs, Ti-Core 200 lbs, Ti-Core with bonding agent 211 lbs and Core-Post 192 lbs. Ti-Core did show evidence of more strength than core-paste composite, also with application of dentin bonding agent more loads required to cause failure. The present study reveals that titanium filler has improved the properties of composite. The application of bonding agent may result in a closer adaptation of material to the tooth structure. However, these improvements are statistically insignificant. Gutmann JL, Dutoit I, Louw N2 (Baylor College of Dentistry 1, Dallas, USA and University of Stellenbosch, Tygerberg, Republic of South Africa). Comparative strengths of dentin-bonded core build-ups. J Dent Res (IADR Abstracts), 1992;72:1948. The comparative strengths of dentin-bonded core build-up material for pulpless teeth were evaluated. Forty-four extracted, intact mandibular molars were endodontically accessed and had their crowns reduced to a height of 3.5 + 0.75 mm from the floor of the pulp chamber. To equalize tooth size in each group, the samples were sorted into four groups of 11 teeth each based on occlusal surface area (ANOVA revealed no significant differences between the mean surface areas in each group) and restored with : I - admixed amalgam (Dispersalloy); II - Admixed amalgam with Amalgambond ; III - Ti-Core with Amalgambond and IV - Fluorocore with Amalgambond to the depth of the pulp chamber. The placement of the cores were 3.75 + 0.25

mm above the coronal tooth surface. Teeth were mounted in acrylic cores in brass rings, which were placed at a 45o angle in a jig. A tensile testing machine applied a controlled force at a crosshead speed of 5 mm/min to the buccal-occlusal angle of the core material which had been ground 2 mm wide at a 45º angle to the long axis of the mounted tooth. The force required to fracture the tooth/core complex was recorded by both an X-Y plotter and computer which registered voltage output every 20 mili-seconds. Statistical analysis indicated a very high correlation coefficient in all groups (0.974 to 0.994 - p<0.001) between the plotter and the computer readout during force application. Mean forces (Newtons) required to fracture the tooth/core build-up were: I - 3100; II - 2885; III - 2753; and IV - 2984. No significant differences were noted (ANOVA, p>0.05) in the forces required to fracture the samples, however greater numbers of teeth fractured as opposed to core fractures. The results suggest equivalent strengths in core build-ups have been achieved with the materials tested. Cohen BI, Deutsch AS, Condos S, Musikant BL, Scherer W. Compressive and diametral tensile strength of titanium reinforced composites. Journal Esthetic Dentistry. 1992;4:50-5. This article determines the compressive and diametral tensile strength of two titanium-reinforced composites (Bis-GMA based), Ti-Core and Flexi-Flow cem with titanium and compares their strengths to dentin and commercially available core materials and cements. In addition scanning electron microscope (SEM) photographs were taken of Ti-Core and Flexi-Flow cem with titanium. Compressive tensile loading was performed on a modified universal testing apparatus. Ti-Core and Flexi-Flow cem with titanium were measured to have compressive strengths of 41,132 and 41,876 psi and tensile strengths of 5,219 and 4,930 psi, respectively. Statistically (ANOVA, one-way analysis of variance), these titanium-reinforced composites are stronger in compressive and tensile strength than Ketac-Silver, Fleck's zinc cement, Durelon, Ketac-Cem, and GC Miracle Mix. Both titanium-reinforced composite materials approach the compressive and diametral tensile strengths of dentin (43,100 and 6000 psi). SEMs revealed that the titanium was uniformly and homogeneously interspersed within the resin matrix of the material. 1. Compressive strength for the titanium-reinforced composite resins was statistically greater than any other group tested and very close to the strength of dentin. 2. Diametral tensile strength of the titanium-reinforced composite resins was statistically greater than any other group tested except for Den-Mat Core Paste. Their strengths were also very close to the strength of dentin. 3. SEM revealed that the titanium was homogeneously incorporated within the resin matrix of the composite resin. Cohen BI, Condos S, Deutsch AS, Musikant BL. Comparison of the shear bond strength of a titanium


composite resin material with dentinal bonding agents versus glass ionomer cements. J Prosthet Dent 1992;68:904-9. This study compared the in vitro shear bond strength of an autopolymerizing composite resin system (CR) (Ti-Core) with two third-generation dentinal bonding agents (DBA) (Tenure and Scotchbond 2) to glass ionomer cements (GIC) (Ketac-Silver, GC Miracle Mix, and Ketac-Cem). The experiment was divided in five groups. The shear bond strengths were evaluated on a universal testing apparatus at three different intervals; 15 minutes, 24 hours, and 7 days. Statistically, (two-way analysis of variance), the shear bond strengths from the greatest to least were: Ti-Core with Tenure DBA> Ti-Core CR with Scotchbond 2 DBA> Ketac-Silver GIC, GC Miracle Mix GIC> Ketac-Cem GIC. There were no differences in shear bond strengths according to time, and no interactions between groups and time. The shear bond strengths for Tenure DBA with Ti-Core CR were two and a half to three times greater than the silver-filled glass ionomers, Ketac-Silver GIC and GC Miracle Mix GIC. Tenure DBA with Ti-Core CR also had consistently greater shear bond strengths than Scotchbond 2 DBA with Ti-Core CR, and this trend is in agreement with similar research. 1. A statistical analysis revealed that the shear bond strengths from the greatest to the least were: Ti-Core CR with Tenure DBA> Ti-Core CR with Scotchbond 2 DBA> Ketac-Silver GIC, GC Miracle Mix GIC> Ketac-Cem GIC. 2. There were no differences in the shear bond strengths with time and no evidence of interactions between groups and time. 3. The shear bond strengths of Tenure DBA with Ti-Core CR were two and a half to three times greater than for the silver-reinforced glass ionomer cements Ketac-Silver GIC and GC Miracle Mix. Kovarik RE, Breeding LC, Caughman WF. Fatigue life of three core materials under simulated chewing conditions. J Prosthet Dent 1992;68:584-90. There has been an increase in the use of prefabricated post systems to restore endodontically treated teeth. Various restorative materials are being used as core buildups on these posts. The purpose of this study was to compare three core materials that are used with prefabricated stainless steel posts. Two types of prefabricated posts were placed in extracted teeth, followed by core buildups in amalgam, composite resin, or glass ionomer. The teeth were prepared for full cast crowns with margins of the crown preparation extending 0.5 to 1.00 mm below the margins of the core buildup. Crowns were fabricated and cemented with zinc phosphate cement. A custom designed chewing machine was used to cyclically load the teeth with vertical and horizontal forces for one million cycles or until failure occurred. Results indicated highly significant differences in the survival of the post-core-crown restorations depending on which core buildup material was used. Amalgam cores had the lowest failure rate,

followed by composite resin cores. All teeth restored with crowns over glass-ionomer core buildup failed. The type of prefabricated post used had no effect on the survival of the post-core-crown restorations regardless of the core buildup used. 1. Teeth restored with amalgam cores and prefabricated posts had a significantly lower failure rate than teeth restored with composite resin or reinforced glass ionomer cores and prefabricated posts. 2. Teeth restored with amalgam cores provided significantly more rigid abutments for crowns and fixed partial denture retainers than did glass ionomer or composite resin cores. 3. Under the conditions used in this study, reinforced glass ionomer cores did not have adequate strength to withstand simulated occlusal forces. Cohen BI, Condos S, Deutsch AS, Musikant BL. Fracture strength for three different core materials in combination with three different endodontic posts. Int'l J Prosthdodont 1994;7:178-182. The purpose of this study was to determine the fracture load for three different core materials supported by three different post systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3 x 3 factorial two-way analysis of variance (p<0.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were: Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin, 100.6; Parapost/Tytin, 134.6; Flexi-Post/ Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and Parapost/Ketac-Silver, 37.7. The titanium composite, Ti-Core, had the greatest fracture load values in all instances; the silver-filled glass-ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthreaded, Vlock, had the greatest fracture load values, and the Parapost had the least. Both the Flexi-Post and the Vlock post have large bulky heads with many vertical and horizontal grooves, apparently facilitating the locking of the core material into the post. Musikant BL, Cohen BI, Condos S, Deutsch AS. One year fluoride release data from four reinforced composite resins. J Dent Res 1994;73 Abstracts 1797:326. The aim of this study was to measure the fluoride release (measured in parts per million (ppm)) in deionized water for four fluoridated composites for over a 1 year period (Ti-Core (group 1), Ti-Core Natural (group 2), Flexi-Flow cem with titanium (group 3) and Flexi-Flow Natural (group 4)). Repeated measures analysis of variance (RMANOVA) was used to analyze interval and cumulative release data over time and between groups. One-way analysis of variance (ANOVA) (p<0.0001) was used to compare average weekly release between the four groups. Values for fluoride release for 1 day, 7, 14,


21, 30, 45, 60, 91, 180, and 365 days were (ppm): group 1-interval release: 2.77, 3.07, 2.43, 2.07, 2.91, 5.06, 2.91, 5.87, 11.97, 6.61; cumulative: 2.77, 5.83, 8.26, 10.33, 13.24, 18.31, 21.22, 27.08, 39.08, 45.67; group 2-interval release: 1.94, 2.61, 1.36, 1.26, 1.08, 1.58, 2.35, 2.73, 6.10, 8.06; cumulative: 1.94, 4.55, 5.91, 7.17, 8.25, 9.83, 12.18, 14.91, 21.01, 29.08; group 3-interval release: 0.31, 0.29, 0.22, 0.11, 0.15, 0.14, 0.16, 0.15, 0.25, 0.26; cumulative: 0.31, 0.61, 0.82, 0.93, 1.08, 1.22, 1.38, 1.54, 1.79, 2.05; group 4-interval release: 0.69, 0.36, 0.34, 0.20, 0.18, 0.17, 0.15, 0.18, 0.28, 0.29; cumulative: 0.69, 1.06, 1.30, 1.49, 1.68, 1.86, 2.01, 2.19, 2.47, 2.75. The student-Newman Keuls (SNK) test was used to make pairwise comparisons of each group to the other. The mean weekly release was similar for both Flexi-Flow Natural and Flexi-Flow with titanium. The Ti-Core systems (groups 1 and 2) were both different from the Flexi-Flow systems and were different from one another. Therefore, Ti-Core with titanium (group 1) yielded the greatest amount of fluoride over a 52-week period, followed closely by Ti-Core Natural (group 2). The amount of fluoride released for these systems (groups 1-4) seems to be in the range found for other dental cements and composites. Citation in Compendium of Continuing Education in Dentistry 1994;XV:600. Post and Core Combination Affects Fracture Resistance. Cohen et al (Int Prosthodont 1994;7(2):178-182) tested the fracture load for three core materials using three types of stainless steel post systems. The core materials were a titanium-reinforced resin composite, an amalgam of mercury, silver, tin, and copper, and a ceramic-metal composition of silver-reinforced glass-ionomer material. Each of these core materials was tested with each of the three post systems (a microthreaded parallel post, a passive post, and a system with a split-shank design) on 90 extracted single rooted human teeth. Each combination of tooth, post and core was mounted in an acrylic resin block, kept in 100% humidity for 1 week, put into a special jig, and placed in a universal testing machine until the core became displaced from its post head. All of the samples failed at the core, there were no fractures of the post or the tooth. The only significant differences between types of post were for the amalgam core material when tested with the split-shank design post system and the microthreaded parallel post system, in which the split-shank system showed a higher mean resistance. The titanium-reinforced composite core material combined with the microthreaded parallel post system had a higher mean resistance than the titanium-reinforced resin composite and the passive post system. Results also showed that the microthreaded parallel post system had the best fracture resistance when used with the titanium-reinforced resin composite; the split-shank design had highest fracture resistance with the titanium-reinforced resin composite and the amalgam. The authors concluded that the titanium-reinforced resin composite core material had the best fracture resistance, and the

passive post system gave the least fracture resistance to any of the core materials tested. The Dental Advisor Plus. January/February 1995;5:1. Flexi-Flow ++++1/2 (Essential Dental Systems, Inc., 89 Leuning St., S. Hackensack, NJ) TDA PLUS Recommendation Flexi-Flow is a highly recommended resin cement for cementation of posts. It received a 92% approval rating. Description Flexi-Flow is a titanium-reinforced, fluoride releasing composite cement specifically designed for post placement. The cement has relatively high compressive and tensile strengths and is radiopaque. Twenty-seven consultants used Flexi-Flow with Flexi-Flange and EDS’ AccessPost in over 250 clinical applications. Positive Features Flexi-Flow is nicely packaged with easy to follow instructions. The cement dispenses and mixes easily. The viscosity was rated better than average, resulting in a cement that flows easily into the post space and results in complete seating of the post. Working time is adequate and removal of excess cement is easy. Flexi-Flow is compatible with most dentin bonding agents. Consultants' Comments The syringe system was preferred to the bottles. Use a dentin bonding agent for better retention. Endodontic filling material containing eugenol may interfere with the set of the resin cement. Ratings Excellent +++++ Very Good ++++ Good +++ Fair ++ Poor + Citation in Dental Products Report in Restorative Dentistry Techniques. DPR 1995:136. In their works, Drs. Cohen et al (referenced) believe that core build-up materials should have a strength similar to dentin. Especially in restorations where the core is composed of both dentin and core material. They also found that similar strengths prevent uneven flexure of the material under function and that similar compressive and diametral tensile strength with dentin helps to lessen ditching during core preparation. (The comp-ressive strength of dentin is 43,100 psi, and the diametral tensile strength is 6,000 psi). In addition to these factors in selecting a core material, doctors should always be concerned about bio-compatibility and pulpal irritation. Referenced Cohen BI, et al. "compressive and diametral tensile strength of titanium reinforced composites." J Esthetic Dentistry 1992;4:50-55.


Cohen BI, Deutsch AS, Condos S, Musikant BL, Scherer W. Resistance a la compression et a la torsion de composites renforces au titane. Endo:Revue Francaise This article determines the compressive and diametral tensile strength of two titanium-reinforced composite (Bis-GMA-based) and compares their strength to dentin and commercially available core materials and cements. In addition scanning electron microscope (SEM) photographs were taken of Ti-Core and Flexi-Flow cem with titanium. Compressive and tensile loading was performed on a modified universal testing apparatus. Statistically, these titanium-reinforced composites are stronger in compressive and tensile strength than Ketac-Silver, Fleck's zinc cement, Durelon, Ketac Cem and GC Miracle Mix. Both titanium-reinforced composite materials approached the compressive and diametral tensile strength of dentin. SEM's revealed that the titanium was uniformly and homogeneously interspersed within the resin matrix of the material. Cohen BI, Deutsch AS, Musikant BL. Fluoride release from four reinforced composite resins: A one year study. Oral Health 1995;April:7-14. Four fluoridated composite resins were described and separated into four groups. Two composite resins were high viscosity core materials Ti-Core (group 1) and Ti-Core Natural (group 2) and two were low viscosity post cements Flexi-Flow cement with titanium (group 3) and Flexi-Flow Natural (group 4). This study recorded the fluoride release measured in parts per million in deionized water for each of four fluoridated composite resins for one year. Repeated measures analysis of variance (RMANOVA) was computed to separately analyze internal release and cumulative release over time and between groups. One-way analysis of variance (ANOVA) (p<0.0001) was selected to compare average weekly release between the four groups. The Student-Newman-Keuls (SNK) these revealed that the mean weekly release was similar for both Flexi-Flow Natural and Flexi-Flow with titanium. The Ti-Core systems of groups 1 and 2 were both different from the Flexi-Flow systems and different from each other. Ti-Core with titanium group 1 yielded the greatest fluoride release over a 52-week period, followed closely by Ti-Core Natural of group 2. The fluoride released for these systems in groups 1-4 was similar to the ranges reported in other fluoridated dental cements and composite resins. Ziebert AJ, Dhuru VB. The fracture toughness of various core materials. J Prosthod 1995;4:33-37. This study determined the fracture toughness of four core buildup materials. Single-edge notch, bar-shaped specimens conforming to the American Society for Testing Materials standard E-399 were fabricated for a high copper amalgam alloy, two composite resins, and a glass ionomer buildup

material. The specimens were stored in air for 1 week and then tested in three-point bending mode with an Instron Universal Testing Machine (Instron Corporation, Canton, MA). Fracture toughness values obtained were as follows: Fluorocore (composite resins; Caulk, Milford, DE), 1.54 MN .m-1.5; Ti-Core (composite resin and titanium; Essential Dental Systems, S. Hackensack, NJ) 1.34 MN. m-1.5; Valiant Ph.D. (amalgam; Caulk), 1.29 MN.m -1.5; and Coreshade Glass Ionomer Base Cement (Shofu Inc., Kyota, Japan), 0.55 MN.m-1.5. Glass ionomer materials are probably unsuitable as core buildup materials because of their relatively low fracture toughness. Fluorocore, Ti-Core, and amalgam all had fracture toughness values significantly greater than the glass ionomer (p< 0.01) and were statistically similar. Cohen BI, Deutsch AS, Condos S, Musikant BL, Scherer W. Fuerza compresiva y diametral tensora de compuestos de titanio reforzado. Practica Odontologica 1995;16:20-27. A new class of titanium-reinforced composite resin was examined. A cement and a core material were tested for compressive and diametral tensile strength. SEM examination of the materials was also preformed. 1) Compressive strength for the titanium-reinforced composite resins was statistically greater than any other group tested and very close to the strength of dentin. 2) Diametral tensile strength of the titanium reinforced composite resins was statistically greater than any other group tested except for Den-Mat Core Paste. Their strengths were also very close to the strength of dentin. 3) SEM revealed that the titanium was homogeneously incorporated within the resin of the composite. Dental Advisor PLUS. January/February 1996;Vol. 6: No.1. Flexi-Flow Natural ++++ 1/2 (Essential Dental Systems, Inc., 89 Leuning St., So. Hackensack, NJ 07606 800-223-5394). TDA PLUS Recommendation Flexi-Flow Natural is a highly recommended, self-cured resin cement. It received a 91% approval rating. Description Flexi-Flow Natural is a titanium and lanthanide-reinforced, self-cured, multi-purpose, composite cement with sustained fluoride release. The cement is insoluble, radiopaque, and is Vita Shade A-3. Fifteen


consultants used Flexi-Flow Natural in over 100 clinical cases. Positive Features Flexi-Flow Natural is a color modification of the original gray Flexi-Flow evaluated in The Dental Advisor Plus January/February 1995, Vol. 5, No. 1. Consultants appreciated the packaging and overall ease of use of Flexi-Flow Natural. Working time is adequate, and the mixed cement has good viscosity and flow. It can be spun into the prepared canal space with the aid of a lentulo spiral for post cementation. The excess cement is easily removed, and final set occurs in less than five minutes. Seventy-five percent of consultants commented that Flexi-Flow Natural was better than the cement they were currently using. Consultants' Comments - Use a self-cured dentin bonding agent for maximum retention. - All remnant eugenol should be properly removed before cementing with a resin cement. Ratings Excellent +++++ Very Good ++++ Good +++ Dental Advisor Plus. January/February 1996;Vol. 6: No. 1. Ti-Core Natural ++++ (Essential Dental Systems, Inc., 89 Leuning St., So. Hackensack, NJ 07606 800-223-5394). TDA PLUS Recommendation Ti-Core Natural is a highly recommended, self-cured composite core build-up material. It received an 89% approval rating. Description Ti-Core Natural is a titanium and lanthanide filled, two-paste, self-cured composite for core build-ups. It is supplied in Vita Shade A-3 to prevent "show through" beneath all-ceramic restorations and has continuous fluoride release. Fifteen consultants evaluated Ti-Core Natural in 290 clinical cases. Positive Features Ti-Core Natural is a color modification of the original gray Ti-Core. Consultants opinion of it were consistent with those of the Ti-Core evaluation in The Dental Advisor Plus January 1992, Vol. 2, No. 1. The material is easy to dispense and mix, and when used in a syringe, it is free flowing for placement into the prepared tooth and undercuts. Working and setting times are adequate for all clinical situations. Ti-Core Natural feels like tooth structure during preparation

and resists fracture. It is compatible with most dentin bonding agents. Consultants' Comments - Color differentiation from tooth structure is difficult in deep margins and/or on posterior teeth. - Syringe delivery is preferred, as the material is somewhat sticky. Ratings Excellent +++++ Very Good ++++ Good +++ Cohen BI, Pagnillo M, Musikant BL, Deutsch AS, Cofrancesco G. Comparison Of The Young's Modulus For Six Reinforced Dental Materials. Oral Health 1997;April:47-55. The purpose of this in vitro study was to compare the Young's modulus of four reinforced core materials and two reinforced resins cements using a non-destructive testing apparatus (GrindoSonic's system). Six groups with 10 samples each were used and the Young's modulus values were compared. A one-way analysis of variance (ANOVA) followed by the Newman-Keuls pairwise multiple comparison tests were performed. All results were considered statistically significant if p< 0.05. The Newman-Keuls multiple comparisons test showed that there were four distinct groupings that differed from each other (p<0.0001). The rankings in descending order were; Ti-Core Natural (22.20 GPa) >Ti-Core with Titanium (18.53 GPa) > Ketac-Silver (14.00 GPa)> Flexi-Flow with titanium (11.09 GPa), Flexi-Flow Natural (10.00 GPa), GC Miracle Mix (9.40 GPa). The high Young's modulus for Ti-Core with titanium and Ti-Core Natural coupled with the high compressive and tensile strength makes these materials very suitable as core material. The low Young's moduli for the glass ionomers, Ketac-Silver and GC Miracle Mix coupled with low compressive and diametral tensile strengths values for these materials makes them not suitable as a dental restoratives. Friedlander C, Tamse A, Fuss Z, Gordon M. Sealing ability of three dental cements following cementation of endodontic posts in vitro. European Society of Endodontology 1995;November:2. The aim of this study was to determine the sealing ability of three different dental cements to coronal microleakage following cementation of endodontic posts. Sixty five single-rooted extracted teeth were cut at the cemento-enamel junction and endodontically prepared. The coronal 6mm of each root canal was prepared for a Dentatus post. Each of the three dental cements, composite Flexi-Flow (Essential Dental Systems, S. Hackensack, NJ) (FF), Carboxylate (D), zinc phosphate (ZP), was inserted into 20 root canals using a lentulo followed by passive placement of the posts. The teeth were completely coated with varnish except for the


coronal 2 mm and were submitted to dye penetration (basic fuchsin) in vacuum for 72 hours. Then the teeth were cut horizontally from the coronal orifice to 1 mm apical to the post at 1 mm intervals using a diamond wafering blade (Buehler) on a sectioning machine. The specimens were examined under a stereo microscope for microleakage. The FF group showed significantly (P<0.05) less microleakage between the cement and the dentinal wall. The ZP group showed the greatest microleakage through the material and no significance difference was found in microleakage between the cements and the metal post. Cohen BI, Condos S, Deutsch AS, Musikant BL. Fuerza de fractura de tres tipos de materiales para el munon, en combinacion con tres espigas endodoncicas distintas. Practica Odontologica 1995;16 (10):40-47. The purpose for this study was to determine the fracture load for three different core materials supported by three different posts systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3x 3 factorial two-way analysis of variance (p<.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were: Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/ Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin 100.6; Parapost/Tytin, 134.6; Flexi-Post/Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and Parapost/ Ketac-Silver, 37.7; The Titanium composite, Ti-Core, had the greatest fracture load values in all instances; the silver-filled glass-ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the Parapost had the least. Both the Flexi-Post and the Vlock post have large bulky heads with many vertical and horizontal grooves, apparently facilitating the locking of the core material into the post. Cohen BI, Condos S, Deutsch AS, Musikant BL. Comparacion de resistencias entres dos productos dentales: Resina compuesta y cementos de ionomero de vidrio. Practica Odontologica 1995;16 (5):15-20. This study compared the in vitro shear bond strength of an autopymerizing composite resin system (CR) (Ti-Core) with two third-generation dentinal bonding agents (DBA) (Tenure and Scotchbond 2) to glass ionomer cements (GIC) (Ketac-Silver, GC Miracle Mix and Ketac-Cem). The experiment was divided in five groups. The shear bond strengths were evaluated on a universal testing apparatus at three different intervals: 15 minutes, 24 hours, and seven days. Statistically (two-way analysis of variance), the shear bond strengths from the greates to least were; Ti-Core CR with Tenure DBA> Ketac-Cem GIC. There were

no differences in shear bond strengths according to time, and no interactions between groups and time. The shear bond strengths for Tenure DBA with Ti-Core CR were two and half to three times greater than the silver-filled glass ionomer Ketac-Silver GIC and GC Miracle Mix GIC. Tenure DBA with Ti-Core CR also had consistenly greater shear bond strengths than Scotchbond 2 DBA with Ti-Core CR, and this trend is in agreement with similar research. Cohen BI, Deutsch AS, Condos S, Musikant BL, Scherer W. Wytrzymalosc na sciskanie i rozciaganie materialow zlozonych wzbogaconych tytanem. Stomat Wspolczesna 1996;Vol.3 Nr. 1:31-37. This article determines the compressive and diametral tensile strength of two titanium-reinforced composites (Bis-GMA based), Ti-Core and Flexi-Flow cem with titanium and compares their strengths to dentin and commercially available core materials and cements. In addition scanning electron microscope (SEM) photographs were taken of Ti-Core and Flexi-Flow cem with titanium. Compressive tensile loading was performed on a modified universal testing apparatus. Ti-Core and Flexi-Flow cem with titanium were measured to have compressive strengths of 41,132 and 41,876 psi and tensile strengths of 5219 and 4930 psi, respectively. Statistically (ANOVA, one-way analysis of variance), these titanium-reinforced composites are stronger in compressive and tensile strength than Ketac-Silver, Fleck's zinc cement, Durelon, Ketac-Cem, and GC Miracle Mix. Both titanium-reinforced composite materials approach the compressive and diametral tensile strengths of dentin (43,100 and 6000 psi). SEMs revealed that the titanium was uniformly and homogeneously interspersed within the resin matrix of the material. Cohen BI, Condos S, Deutsch AS, Musikant BL. Fracture strength of three different core materials in combination with three different endodontic posts. Abstract citation in the Int Endodo J 1996;29:51. The purpose of this study was to determine the fracture load for three different core materials supported by three different post systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine. A 3 X 3 factorial two-way analysis of variance (P<.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were, Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/ Tytin, 100.6; ParaPost/Tytin, 134.6; Flexi-Post/Ketac-Silver, 69.4; Vlock/ Ketac-Silver, 50.4; and ParaPost/ Ketac-Silver, 37.7. The titanium composite, Ti-Core had the greatest fracture load values in all instances: the silver-filled glass ionomer specimen, Ketac-Silver,


had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the ParaPost had the least. Both the Flexi-Post and Vlock post have large bulky heads with many vertical and

horizontal grooves, apparently facilitating the locking of the core material into the post. Nash R, Rosenthal L, Pescatore C. Chariside:Core

Materials-State of the Art. Compendium 1996;June Vol.17, No.6:530-536. Cores are placed to increase the resistance and retention form for the final restoration. The core fills the chamber and access opening and replaces any lost tooth structure. Bonded reinforced composite resins that contain fluoride, such as Ti-Core, are the materials of choice. If more severe undercuts are present, they can

be blocked out with a hybrid resin. For nonvital teeth, the literature often supports the placement of either a core build-up or post-and-core before final preparation. The same principle that applies to vital teeth should also apply to nonvital teeth.

Cohen BI, Deutsch AS, Condos S, Musikant BL, Scherer W. Die Kompressive und diametrale bruchfestigkeit von titan-verstarkten composites. ZWR 1996;105,No.7/8:105. This article determines the compressive and diametral tensile strength of two titanium reinforced composites (Bis-GMA based), Ti-Core and Flexi-Flow cem with titanium and compares their strengths to dentin and commercially available core materials and cements. In addition scanning electron microscope (SEM) photographs were taken of Ti-Core and Flexi-Flow cem with titanium were measured to have compressive strengths of 41,132 and 41 876 psi and tensile strengths of 5219 and 4930 psi, respectively. Statistically (ANOVA, one-way analysis of variance), these titanium-reinforced composites are stronger in compressive and tensile strength than Ketac-Silver, Fleck's zinc cement, Durelon, Ketac-Cem and GC Miracle Mix. Both titanium-reinforced composite materials approach the compressive and diametral tensile strengths of dentin (43,100 and 6000 psi. SEM's revealed that the titanium was uniformly and homogeneously interspersed within the resin matrix of the material.

Cohen BI, Deutsch AS, Condos S, Musikant BL, Scherer W. Resistenza alla compressione e tensione diametrale di compositi reinforzati al titanio. Edizioni Minerva Medica 1995;Vol.13 N.3-4:89-96. This article determines the compressive and diametral tensile strength of two titanium reinforced composites (Bis-GMA based), Ti-Core and Flexi-Flow cem with titanium and compares their strengths to dentin and commercially available core materials and cements. In addition scanning electron microscope (SEM) photographs were taken of Ti-Core and Flexi-Flow cem with titanium were measured to have compressive strengths of 41,132 and 41 876 psi and tensile strengths of 5219 and 4930 psi, respectively. Statistically (ANOVA, one-way analysis of variance), these titanium-reinforced composites are stronger in compressive and tensile strength than Ketac-Silver, Fleck's zinc cement, Durelon, Ketac-Cem and GC Miracle Mix. Both titanium-reinforced composite materials approach the compressive and diametral tensile strengths of dentin (43,100 and 6000 psi. SEM's revealed that the titanium

was uniformly and homogeneously interspersed within the resin matrix of the material. Cohen BI, Pagnillo MK, Condos S Deutsch AS, Musikant BL. Four Different core materials measured for fracture strength in combination with five different endodontic post designs. J Prosthet Dent 1996;76:487-95. The purpose of this in vitro study was to determine the fractural load of four core materials supported by five post designs. This study was divided into 20 groups with 10 samples per group. Specimens were placed in a special jig at a 45 degree angle, and the fracture load values, in pounds, were obtained with the use of a universal testing machine. A 5x4 factorial design was used to compare the fractural strength and a two-way analysis of variance (ANOVA) was used to determine whether the buccolingual, mesiodistal and height dimensions differed across groupings. Mean fracture load values were observed with Flexi-Post dowel/Ti-Core material 277.1 pounds, ParaPost dowel/Tytin silver amalgam 277.3 pounds with the greatest mean values and ParaPost dowel/Ketac-Silver material with the lowest mean value (49.6 pounds). For all posts, Tytin silver amalgam and Ti-Core materials were significantly stronger than Ketac-Silver and GC Miracle Mix material. Ketac Silver and GC Miracle Mix materials did not differ from each other. The greatest loads were recorded for the ParaPost dowel/Tytin silver amalgam combination follow by Flexi-Post dowel/Ti-Core material and Flexi-Flange dowel/Ti-Core material. These values were not statistically different. ParaPost dowel/Ketac Silver material had the lowest fractural load. Results indicated that Ti-Core material is at least as strong as Tytin silver amalgam. Cohen BI, Deutsch AS, Condos S, Musikant BL, Scherer W. Resistencias compresiva y diametral de resinas compuestas reforzadas con titanio. Rev Asoc Odontol Argentina 1996;Vol.84, No.2:140-146. This article determines the compressive and diametral tensile strength of two titanium reinforced composites (Bis-GMA based), Ti-Core and Flexi-Flow cem with titanium and compares their strengths to dentin and commercially available core materials and cements. In addition scanning electron microscope (SEM) photographs were taken of Ti-Core and Flexi-Flow cem with titanium were measured to have compressive


strengths of 41,132 and 41,876 psi and tensile strengths of 5,219 and 4,930 psi, respectively. Statistically (ANOVA, one-way analysis of variance), these titanium-reinforced composites are stronger in compressive and tensile strength than Ketac-Silver, Fleck's zinc cement, Durelon, Ketac-Cem and GC Miracle Mix. Both titanium-reinforced composite materials approach the compressive and diametral tensile strengths of dentin (43,100 and 6000 psi. SEM's revealed that the titanium was uniformly and homogeneously interspersed within the resin matrix of the material.

Al-Wazzan K, Harbi AA, Hammad I. King Saud University College of Dentistry & Security Forces Hospital, Saudi Arabia. J Dent Res Abstract 1996;75(5);1284. Composite resin can be bonded to dentin by using proper bonding agents. The purpose of this study is to investigate the effect of eugenol on the bond strength of composite resin (Fluorocore and Ti-Core) core material to dentin. Dentin were exposed in three groups of the extracted teeth (20 samples each). Dentin were completely covered in one group with eugenol contained temporary cement, the other group was covered in one group with eugenol contained temporary cement, the other group was covered with noneugenol temporary cement and, the third group was left uncovered as control group. All the samples were stored for one week at 37oC and 100% humidity. The dentin surfaces were cleaned and treated by the Gluma bonding system followed by core buildups. The following were the results of shear testing: There was a significant (P<0.001) reduction of the bond strength for the sample covered with eugenol temporary cement. There was no significant difference between the controlled group and the noneugenol temporary cement covered group. Bonding the Ti-Core materials to the dentin was significantly higher than the Fluorocore.

Cohen BI, Deutsch AS, Musikant BL. Uwalnianie fluoru z czterech materialow zlozonych (wyniki po rocznej obserwacji). Stomatologia Wspolczesna 1996;Vol.3, Nr.5:403-407. Four fluoridated composite resins were described and separated into four groups. Two composite resins were high viscosity core materials Ti-Core (group 1) and Ti-Core Natural (group 2) and two were low viscosity post cements Flexi-Flow cement with titanium (group 3) and Flexi-Flow Natural (group 4). This study recorded the fluoride release measured in parts per million in deionized water for each of four fluoridated composite resins for one year. Repeated measures analysis of variance (RMANOVA) was computed to separately analyze internal release and cumulative release over time and between groups. One-way analysis of variance (ANOVA) (p<0.0001) was selected to compare average weekly release between the four groups. Student-Newman-Keuls (SNK) revealed that the mean weekly release was similar for both Flexi-Flow Natural and Flexi-Flow with titanium. The Ti-Core systems of groups 1 and 2 were both different from the Flexi-Flow systems and different from each other. Ti-Core with titanium group 1 yielded the greatest fluoride release over a 52-week period, followed closely by Ti-Core Natural of group 2. The fluoride released for these systems in groups 1-4 was similar to the ranges reported in other fluoridated dental cements and composite resins. Cohen BI, Condos S, Deutsch AS, Musikant BL. Resistenza a frattura di tre materiali di ricostruzione in combinazione con tre perni endocanalari. Il Dentista Moderno 1196;9:1289-1293. The purpose of this study was to determine the fracture load for three different core materials supported by three different post systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were

obtained using a universal testing machine a 3 x 3 factorial two-way analysis of variance (p<0.0408) was used to test the effects of core material and post type on the fractural resistance. Ti-Core had the greatest fracture load values in all instances, Ketac-Silver had the least. Flexi-Post and Vlock-Post had the greates fracture load values, while ParaPost had the least. Both Flexi-Post and Vlock Post have large bulky heads with many vertical and horizontal grooves, apparently facilitating the locking of the core materila into the post. Musikant BL, Cohen BI, Pagnillo M, Deutsch AS. Young's modulus for six reinforced dental materials. J Den Res (IADR Abstracts) 1997;76;513. The purpose of this in vitro study was to compare the Young's modulus of four reinforced core materials and two reinforced resins cements using a GrindoSonic non-destructive testing apparatus. The experiment was divided into six groups with ten samples for each material studied. Cylindrical samples were placed on a

special jig and a microphone was placed under the sample in order to pick up simulated vibrations caused by an electromagnetic metal hammer. Young's modulus vaules were calculated from; E = 1.6067(L3/D4)(m)(ff

2)T1' where E = Young's modulus (GPa), L = length of the cylinder (mm), D = diameter of cylinder (mm), m = mass of the cylinder, ff = fundamental resonant frequency of cylinder in flexure (Hz) and T1' = correction factor for flexural mode for the cylinder. The Young's modulus values (measured as GPa) were compared using a one-way analysis of variance (ANOVA) followed by the Newman-Keuls pairwise multiple comparison test. Results were considered statistically significant if p<0.05. The Newman-Keuls multiple comparison tests showed that there were four distinct groupings that differed from each other (p < 0.0001). The rankings in descending order were; Ti-Core Natural (22.20 GPa) > Ti-Core with Titanium (18.53 GPa) > Ketac-Silver (14.00 GPa) > Flexi-Flow with Titanium (11.09 GPa), Flexi-Flow


Natural (10.00 GPa), GC Miracle Mix (9.40 GPa). Ti-Core with Titanium (18.53 GPa) and Ti-Core Natural (22.20 GPa) had the highest Young's modulus, coupled with their high strength values suggested that these materials are favorable as core restoratives. The low Young's modulus for the glass ionomers, Ketac-Silver (14.00 GPa) and GC Miracle Mix (9.40 GPa) coupled with low strength values, it is suggested that they are not ideal as restorative materials. Flexi-Flow with Titanium (11.09 GPa) and Flexi-Flow Natural (10.00 GPa) had low Young's modulus, with their high strength values, it is suggest that these materials are ideal as post cementation agents. Deutsch AS, Cohen BI, Pagnillo M, Condos S, Musikant BL, Cofrancesco G. Fracture Strength of Four Core Materials Supported by Five Post. J Den Res (IADR Abstracts) 1997;76:555. The purpose of this in vitro study was to determine the fractural load of four core materials (Ti-Core, Tytin amalgam, Ketac-Silver and GC Miracle Mix) supported by five post designs (Flexi-Post (FP), Flexi-Flange (FF), EDS’ AccessPost (AP), ParaPost (PP) and C-Post (CP)). The study was divided into 20 groups with each group consisting of 10 samples. A total of 200 recently extracted, single-rooted human teeth were used in this study. Post preparations were made for FP No. 2, FF No. 2, AP No. 2, PP No. 6 and CP No. 2, all equivalent to a Flexi-Post No. 2 dowel. The posts were luted in the corresponding root canals with zinc phosphate cement and were allowed to set for 1 hour. For Ti-Core and Tytin silver amalgam, no bonding agents were used. Ketac-Silver and GC Miracle Mix were pre-treatment with 40% polyacrylic acid. All cores were prepared freehanded with a 6-to-8 angle and was standardized to a height of 6.0 mm. The tooth-post-core combinations were mounted in acrylic resin blocks and were then placed in 100% humidity at room temperature for 7 days before testing. Specimens were placed in a special jig on a 45 angle and the fracture load values were obtained using (MTS 810) Material Testing Machine with a crosshead speed of 0.635 cm/min. A two-way Analysis of Variance (ANOVA) was used to determine whether the three dimensions, buccolingual, mesiodistal and height differed across groupings. Pearson correlation coefficients were calculated to determine if there were any correlation between fractural strength and any of the three dimensions. None of the tooth parameters differed significantly across posts or cores. A two-way analysis of covariance (ANACOVA) was used to compare mean fractrual strength across all post-core combination. For each ANACOVAs, pairwise multiple comparisons between core types were carried out using Bonferroni-adjusted pairwise independent sample t-test between ANACOVA-adjusted means. As there were six possible pairwise comparisons of cores, a pairwise t-test was considered significant if its p<0.008. Fracture load values (measured in pounds) were: FP/Ti-Core 277.1, FP/Tytin amalgam 187.8, FP/Ketac-Silver 109.3, FP/GC Miracle Mix 111.4; FF/Ti-Core

273.5, FF/Tytin amalgam 234.5, FF/Ketac-Silver 90.9, FF/GC Miracle Mix 110.7, PP/Ti-Core 169.7, PP/Tytin amalgam 277.3, PP/Ketac-Silver 49.6, PP/GC Miracle Mix 72.7, AP/Ti-Core 202.1, AP/Tytin amalgam 232.9, AP/Ketac-Silver 102.6, AP/GC Miracle Mix 121.0, CP/Ti-Core 213.7, CP/Tytin amalgam 189.7, CP/Ketac-Silver 65.3 and CP/GC Miracle Mix 67.9. For all post, Tytin amalgam and Ti-Core are significantly stronger than Ketac-Silver and G-C Miracle Mix which did not differ from one another. The greatest fractural loads were PP/Tytin amalgam with a fractural load of 277.3131.4 follow closely by FP/Ti-Core 277.181.6 and FF/Ti-Core 2743.583.6. PP/Ketac-Silver had the lowest fractural load of 49.618.5. Ti-Core was at least as strong as Tytin amalgam. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Cyclic Fatigue Properties of Four Core Materials Supported by Five Posts. J Dent Res (IADR Abstracts) 1997;76:554. This pilot study concerned the cyclic fatigue of five different endodontic post systems (EDS’ AccessPost (AP), Flexi-Flange (FF), Flexi-Post (FP), ParaPost (PP), and Vlock (V)) with four different core materials (Tytin Silver amalgam (TSA), Ti-Core (TC), Ketac-Silver (KS) and G-C Miracle Mix (GC)). This study was divided into 20 groups. Each group consisted of 5 samples for a total of 100 samples. A total of 100 recently extracted human single rooted teeth were used. The preparations for the post-holes were performed according to manufacturers' instructions. In this study only stainless steel posts were used. All posts were cemented with zinc phosphate cement to eliminate any difference with cements and was allowed to set for at least 1 hour. Core preparations used for either Ti-Core and Tytin amalgam were etched with a 37% phosphoric acid gel and then Scotchbond Multi-Purpose bonding agent was applied. Ketac-Silver and G-C Miracle Mix core preparations used were etched with 40% polyacrylic acid. Fabrication of each core was completed with the use of a hard copper band as the matrix and cores were then trimmed and cut to a standard height of 6 mm. The tooth/post/core combinations were mounted in acrylic resin blocks and were then placed in 100% humidity for 1 week before testing. The specimens were placed in a special jig on a 30 angle on the buccolingual axis and in vitro cyclic fatigue was performed using fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 pounds was applied to each post and core combination for a test configuration of 4,000,000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Results were: AP/TC 4,000,000, AP/TSA 4,000,000, AP/KS 13957, AP/GC 1949795, FF/TC 4,000,000, FF/TSA 4,000,000, FF/KC 115125, FF/GC 2364217, FP/TC 4,000,000, FP/TSA 4,000,000, FP/KS 196503, FP/GC 3206836, PP/TC 4,000,000, PP/TSA 4,000,000, PP/KC 7876, PP/GC 1127135, V/TC 4,000,000, V/TSA 4,000,000, V/KC


23311 and V/GC 2572832. Two-way analysis of variance (ANOVA) was used to compare groups. All post/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4,000,000 cycles with no failures. All post/core samples with Ketac-Silver failed before the 4,000,000 test cycle configuration with all failures being core failures. All post/core samples with G-C Miracle Mix failed in a similar way. Newman-Keuls multiple comparison test, illustrated that Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Al Wazzan KA, Al Harbi AA, Hammad IA.The Effect of Eugenol-Containing Temporary Cement on the Bond Strength of Two Resin Composite Core Materials to Dentin. J of Prosthodontics 1997;6(1):37-42. This study investigated the effect of eugenol-containing temporary cement on the bond strength of two resin composite core materials (FluoroCore and Ti-Core) to dentin. Dentin was exposed in three groups of extracted teeth (20 specimens each). In group one, dentin was covered with eugenol-containing temporary cement; the second group was covered with eugenol-free temporary cement; and the third group was left uncovered and served as a control group. All specimens were stored for 1 week at 37o and 100% humidity. The dentin surfaces were cleaned and treated using the GLUMA adhesive system, followed by placement of composite core build-ups. Debonding of the core material was accomplished using the Accuforce Elite test system. Under the conditions of this investigation, the following conclusions were reached: 1. The use of eugenol-containing materials on dentin can result in a decrease in the bond strength of resin composite core material to dentin, even if the dentin is cleansed with pumice and water and treated with the GLUMA adhesive system before resin composite placement. 2. Eugenol-free temporary cement did not cause an adverse effect on the bond strength between the resin composite core materials tested and dentin. 3. The bond strength of Ti-Core to dentin is significantly higher than that of FluoroCore when used with the GLUMA bonding system. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS, Cofrancesco G. Comparison Of The Young's Modulus For Six Reinforced Dental Materials. Oral Health 1997;April:47-55. The purpose of this in vitro study was to compare the Young's modulus of four reinforced core materials and two reinforced resins cements using a non-destructive testing apparatus (GrindoSonic's system). Six groups with 10 samples each were used and the Young's modulus values were compared. A one-way analysis of variance (ANOVA) followed by the Newman-Keuls pairwise multiple comparison tests were performed. All results were considered statistically significant if p< 0.05.

The Newman-Keuls multiple comparisons test showed that there were four distinct groupings that differed from each other (p<0.0001). The rankings in descending order were; Ti-Core Natural (22.20 GPa) >Ti-Core with Titanium (18.53 GPa) > Ketac-Silver (14.00 GPa)> Flexi-Flow with titanium (11.09 GPa), Flexi-Flow Natural (10.00 GPa), GC Miracle Mix (9.40 GPa). The high Young's modulus for Ti-Core with titanium and Ti-Core Natural coupled with the high compressive and tensile strength makes these materials very suitable as core material. The low Young's moduli for the glass ionomers, Ketac-Silver and GC Miracle Mix coupled with low compressive and diametral tensile strengths values for these materials makes them not suitable as a dental restoratives. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS, Cofrancesco, G. Porównanie midulów Younga szesciu materialów stomatologicznych wzmocnionych jonami metali. Stomatologia Wspolczesna 1997;Nr.2:27-32. (Paper published in Poland’s Stomatologia Wspólczesna (Polish) Comparison of the Young’s Modulus for Six Reinforced Dental Materials.) The purpose of this in vitro study was to compare the Young's modulus of four reinforced core materials and two reinforced resins cements using a non-destructive testing apparatus (GrindoSonic's system). Six groups with 10 samples each were used and the Young's modulus values were compared. A one-way analysis of variance (ANOVA) followed by the Newman-Keuls pairwise multiple comparison tests were performed. All results were considered statistically significant if p< 0.05. The Newman-Keuls multiple comparisons test showed that there were four distinct groupings that differed from each other (p<0.0001). The rankings in descending order were; Ti-Core Natural (22.20 GPa) >Ti-Core with Titanium (18.53 GPa) > Ketac-Silver (14.00 GPa)> Flexi-Flow with titanium (11.09 GPa), Flexi-Flow Natural (10.00 GPa), GC Miracle Mix (9.40 GPa). The high Young's modulus for Ti-Core with titanium and Ti-Core Natural coupled with the high compressive and tensile strength makes these materials very suitable as core material. The low Young's moduli for the glass ionomers, Ketac-Silver and GC Miracle Mix coupled with low compressive and diametral tensile strengths values for these materials makes them not suitable as a dental restoratives. Cohen BI, Condos S, Deutsch AS, Musikant BL. Comparacion De Las Resistencia A Las Fuerzas Opuestas Ejercidas Sobre Los Puntos De Union De La Dentina, Que Llevan Un Material De Resina Con Un Compuesto De Titanio Y Agentes De Enlace A La Dentina, A Los Cementos De Ionomeros De Vidrio. R. Cent. Ci Bioméd. Univ. Fed. Uberlandia 1995;4(1):59-65. (Paper published in Spanish) This study compared the in vitro shear bond strength of an autopymerizing composite resin system (CR) (Ti-Core) with two third-generation dentinal bonding agents (DBA) (Tenure and Scotchbond 2) to glass ionomer cements (GIC) (Ketac-Silver, GC Miracle Mix


and Ketac-Cem). The experiment was divided in five groups. The shear bond strengths were evaluated on a universal testing apparatus at three different intervals: 15 minutes, 24 hours, and seven days. Statistically (two-way analysis of variance), the shear bond strengths from the greatest to least were; Ti-Core CR with Tenure DBA> Ketac-Cem GIC. There were no differences in shear bond strengths according to time, and no interactions between groups and time. The shear bond strengths for Tenure DBA with Ti-Core CR were two and half to three times greater than the silver-filled glass ionomer Ketac-Silver GIC and GC Miracle Mix GIC. Tenure DBA with Ti-Core CR also had consistently greater shear bond strengths than Scotchbond 2 DBA with Ti-Core CR, and this trend is in agreement with similar research. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Cyclic Fatigue Testing of Five Endodontic Post Designs Supported by Four Core Materials. J Prosthet Dent 1997;78(4):458-64. This pilot study examined the cyclic fatigue of five endodontic post systems (EDS’ AccessPost, Flexi-Flange, Flexi-Post, ParaPost, and Vlock) with four core materials (Tytin silver amalgam, Ti-Core, Ketac-Silver and G-C Miracle Mix). In vitro cyclic fatigue was performed with a machine designed to simulate masticatory fatigue forces. An instantaneous force of 22.2 N (5 pounds) was applied to each post and core combination for a test configuration of 4,000,000 repetitions, or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way analysis of variance (ANOVA) was used to compare groups. All posts/core samples with Ti-Core composite and Tytin silver amalgam completed the test with no failures. All posts/core samples with Ketac-Silver material failed before the 4,000,000 test cycle configuration and all failures were core failures. All post/core samples with G-C Miracle Mix material failed in a similar manner. Newman-Keuls multiple comparison test illustrated that, with this simulated fatigue test, Ti-Core material and Tytin silver amalgam were superior to both G-C Miracle Mix and Ketac-Silver materials. Cohen BI, Pagnillo MK, Deutsch AS, Musikant BL. Fracture strengths of three core restorative materials supported with or without a prefabricated split-shank post. J Prosthet Dent 1997;78(6):560-565. The aim of this study was to compare the fracture strengths of three restorative materials, a lanthanide reinforced composite (Ti-Core Natural), a silver amalgam (Tytin), and a hybrid glass ionomer (Advance), supported by either a multi-tiered, threaded split-shank post (Flexi-Flange) or with a dentin spur without a post. A total of 60 recently extracted single-rooted human teeth were divided into six groups of 10. All groups were stored at 100% humidity at room temperature for 1 week before testing. Each specimen was placed in a special jig at a 45-degree angle to the buccolingual axis and subjected to a crosshead speed of 0.63 cm/minute until failure. Two-way analysis of

variance followed by the Newman-Keuls pairwise multiple comparisons test were used to compare the results. There was a statistically significant difference between core materials (p < 0.001), but not regarding post conditions. Ti-Core Natural material had a significantly larger mean failure threshold for fracture than either Tytin silver amalgam or Advance material and the latter two core materials (Tytin and Advance) do not differ from each other. There was no statistical difference between Ti-Core material supported by a post and Ti-Core material supported without a post. This study evaluated the resistance for the core materials supported with or without a post. Ti-Core material supported by a split-shank (Flexi-Flange) post recorded statistically significantly higher fracture resistance than all other core materials supported by a post (Tytin silver amalgam and Advance material). An artificial crown was not used to cover the cores, but the results of this study are important because the strength of the cores were tested in a worst case scenario situation. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS. Shear Bond Strength of a Titanium Reinforced Core Material Using Multi-Step vs. Single-Step Bonding Agents. J Prosthet Dent 1998;80:307-310. The purpose of this in vitro study was to evaluate the shear bond strength of a titanium reinforced core material, Ti-Core using five multi-step bonding systems (Scotchbond Multi-Purpose, OptiBond, All-Bond 2, Tenure, and Probond) and five single-step bonding systems (Single-Bond, OptiBond Solo, One-Step, Tenure Quik, and Prime & Bond 2.1). The experiment was divided into 10 groups with 10 specimens per group. The shear bond strength was evaluated after 24 hours on a MTS universal testing machine with a crosshead speed of 3.40 mm/min. The result (after an ANOVA and a Student-Newman-Keuls test) showed that All-Bond 2 (8.02 MPa) had the greatest shear bond strength (p<0.0001). All other bonding systems were not significantly different from each other. The “single-step” bonding agents did not show an improvement in shear bond strength. The wide range of shear bond strength reported for the “single-step” seems to indicate that these bonding systems are technique sensitive. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of Three Endodontic Posts Cemented with Five Different Types of Dental Cements. J Prosthet Dent 1998;79(5):520-525. The purpose of this study was to compare the retentive values of three different posts (Flexi-Post, EDS’ AccessPost, and ParaPost) cemented with five different cements (Flexi-Flow, zinc phosphate, Advance, Duet, and Ketac-Cem) plus a control group that consisted of a Flexi-Post No. 2 dowel without cement. A total of 160 recently extracted human single-rooted teeth with crowns removed at the cementoenamel junction were divided into 16 groups with 10 samples per group. Post holes were prepared according to manufacturers' instructions. Posts were then cemented with either


Flexi-Flow, zinc phosphate, Advance, Duet, or Ketac-Cem cements. Each sample was placed into a specialized jig and on a tensile testing machine with crosshead speed of 0.638 cm/min applied until failure. A two-way analysis of variance and Newman-Keuls multiple range comparison tests were performed for all cemented groups. A one-way analysis of variance and a Student-Newman-Keuls multiple range comparison test was performed only for the groups with the Flexi-Post dowel, this included the no cement condition. Results were consider to be statistically significant if p<0.05. The Flexi-Post dowel with Flexi-Flow Natural cement obtained the highest retentive value of 303.91 pounds. ParaPost dowel with Duet cement had the lowest retention value of 21.23 pounds. The Flexi-Post dowel had higher mean retention than did EDS’ AccessPost or ParaPost dowels, and EDS’ AccessPost dowel was higher than ParaPost dowel. Flexi-Flow cement had the highest overall mean retention followed, in decreasing order by zinc phosphate, Advance, Ketac-Cem, and Duet cements. Flexi-Post dowel was the most retentive post studied with values ranging from 303.91 pounds with Flexi-Flow Natural cements to 150.93 pounds without cement. Flexi-Flow cements had a higher overall mean retention than other cements studied. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS.Fluoride Release of Four Composite Resins; A Five Year Study. J Dent Res 1998;[Abstract 1068] 239. The purpose of this study was to record the fluoride released measured in parts per million (ppm) of four fluoride composite resins for five years. This study consisted of four groups with three specimens per group, for total of 12 specimens. Two composite resins with high viscosity, Ti-Core with titanium (Group 1) and Ti-Core Natural (Group 2) were core materials and the other two resins studied were low viscosity post cements, Flexi-Flow cement with titanium (Group 3) and Flexi-Flow Natural (Group 4). The disks with diameter of 16.0 mm, thickness of 1.0 mm, and weight of 0.5 grams were placed into a glass jar with 40 mL deionized water. Fluoride concentration was measured with an Accumet 925 microprocessor meter and a solid-state fluoride ion-sensitive electrode. The data was reported in parts per million. Fluoride release from the disk was measured at the following time intervals; day 1, day 7, day 14, day 21, day 30, day 45, day 60, day 90, day 180, day 365 (1 year), 1.5 years, 2 years, 2.5 years, 3 years, 3.5 years, 4 years, 4.5 years, and 5 years were (ppm): Group 1: 2.77, 3.07, 2.43, 2.07, 2.91, 5.06, 2.91, 5.87, 11.97, 6.61, 1.35, 0.50, 0.37, 0.34, 0.28, 0.28, 0.23, and 0.19; Group 2: 1.94, 2.61, 1.36, 1.26, 1.08, 1.58, 2.35, 2.73, 6.10, 8.06, 4.16, 2.47, 1.79, 1.26, 1.05, 0.80, 0.55, and 0.58; Group 3: 0.31, 0.29, 0.22, 0.11, 0.15, 0.14, 0.16, 0.15, 0.25, 0.26, 0.15, 0.10, 0.16, 0.15, 0.15, 0.18, 0.13, and 0.12; Group 4: 0.69, 0.36, 0.24, 0.20, 0.18, 0.17, 0.15, 0.18, 028, 0.29, 0.32, 0.11, 016, 0.17, 0.13, 0.13, 0.14, and 0.12. Fluoride releases were analyzed using repeated measures analysis of variance (RMANOVA) for the individual weekly measurements

and for the cumulative measurements. A one-way analysis of variance (ANOVA) followed by the Student-Newman-Keuls (SNK) pairwise multiple comparisons test was used to compare the average weekly release. All results were considered statistically significant if p < 0.05. The ANOVA showed that average weekly release differed significantly across groups (p < 0.0001). The SNK multiple comparisons test showed that mean average weekly release for Ti-Core with titanium did not differ from Ti-Core Natural, and that Ti-Core with titanium and Ti-Core Natural differed significantly from both Flexi-Flow Natural and Flexi-Flow with titanium, which were not different from one another. Ti-Core with titanium (Group 1) and Ti-Core Natural (Group 2) released statistically greater amounts of fluoride than Flexi-Flow with titanium (Group 3) and Flexi-Flow Natural (Group 4). The fluoride released from these fluoridated resin composites are similar to reported ranges of other fluoride releasing dental restoration materials. Pagnillo MK, Cohen BI, Musikant BL, Deutsch AS. Retention Strength of Three Posts Cemented with Five Different Dental Cements. J Dent Res 1998;[Abstract 221] 133. The purpose of this study was to compare and evaluate the retention values of three different posts (Flexi-Post, EDS’ AccessPost, and ParaPost) cemented with five different cements (Flexi-Flow, zinc phosphate (ZOP), Advance, Duet, and Ketac-Cem). This study was divided into 16 groups with 10 specimens per group. A total of 160 recently extracted human single rooted teeth with their crowns removed at the CEJ were used in this study. Post holes were prepared according to manufacturer's instructions and then cemented with either Flexi-Flow, ZOP, Advance, Duet, or Ketac-Cem. The Flexi-Post control group was prepared without cement (Group 16). The cement for each group was allowed to set for 1 hour before being placed into acrylic blocks. The test specimens were then stored in a 100% humidity environment at room temperature for a week before being tested. The test specimens were placed in a specialize jig and tensile strength using a 810 MTS testing machine (crosshead speed of 0.638 cm/min) was measured until posts were removed from their roots. A 3x5 analysis of variance (ANOVA) was used to find any significant interactions between the three levels of posts and the five different cements. This was followed by a one-way ANOVA and the Newman-Keuls (SNK) pairwise multiple comparison test that compared the five cements and the "no-cement condition" for the Flexi-Post only. All results were considered statistically significant if p<0.05. Flexi-Flow ZOP Advance Duet Ketac-Cem No Cement Flexi-Post 303.9 265.9 189.0 160.8 188.4 150.9 EDS’ AccessPost 89.7 96.2 88.4 41.7 34.5 pounds (sd)


ParaPost 56.2 34.4 51.9 21.2 36.8 Flexi-Post with Flexi-Flow obtained the highest retention value of 303.9 pounds and ParaPost with Duet had the lowest retention value of 21.2 pounds. Flexi-Post had statistically higher retention mean values than did EDS’ AccessPost or ParaPost, with EDS’ AccessPost being higher than ParaPost. Flexi-Flow cement had statistically higher overall retention means followed in decreasing order by ZOP, Advance, Ketac-Cem, and Duet. Flexi-Post was the most retentive post studied with values of 303.9 pounds with Flexi-Flow. Flexi-Flow had statistically higher overall retention means than all other cements studied. The cements based on resin composite's compositions were stronger than cements based on glass ionomers compositions. Musikant BL, Cohen BI, Pagnillo MK, Condos S, Ahmed M. Fracture Resistance of Three Core Materials with or without a Post. J Dent Res 1998;[Abstract 220] 133. The aim of this study was to compare the fracture strengths of three restorative materials supported by either a multi-tiered, threaded split-shank post (Flexi-Flange) or with a dentin spur without a post. This study was divided into six groups with 10 specimens each for a total of 60 recently extracted single rooted human teeth being used. The groups were as follows: Group 1, Tytin silver amalgam with a No. 1 Flexi-Flange dowel, Group 2, Tytin silver amalgam without a post, Group 3, Ti-Core Natural composite with a No. 1 Flexi-Flange dowel, Group 4, Ti-Core Natural composite without a post, Group 5, Advance hybrid glass ionomer with a No. 1 Flexi-Flange dowel, and Group 6, Advance hybrid glass ionomer without a post. For this study 30 recently exacted human teeth had their crown reduced to the cementoenamel junction (CEJ) with diamond bur leaving a dentin spur remaining at the buccol end. The other 30 teeth had their crowns removed at CEJ and were endodontically prepared for a No. 1 Flexi-Flange post according to manufacturer's instructions. Only stainless steel posts were used in this study and were cemented with zinc phosphate cement. For Ti-Core Natural composite and Advance hybrid glass ionomer, All-Bond 2 was used as a bonding agent. These core materials were prepared according to manufacturers' instructions. Tytin silver amalgam used Amalgambond as the bonding agent and the amalgam was place using a standard procedure. All core preparations were standardized to a height of 4.5 mm and then stored at 100% humidity at room temperature for one week before testing. Each specimen was placed in a special jig on a 45 degree angle on the buccolingual axis and subjected to a load, that was recorded in Newtons, using a 810 MTS testing machine with a crosshead speed of 0.63 cm/min until failure. A two-way analysis of variance (ANOVA) followed by the Newman-Keuls pairwise multiple comparisons test were used to compare the results. All results were considered statistically significant if p < 0.05. Ti-Core Natural supported by a Flexi-Flange (Group 3) had a

fracture strength of 950.9 N and Ti-Core Natural without a post (Group 4) had a fracture strength of 1030.4 N. Tytin silver amalgam with a Flexi-Flange (Group 1) had a fracture strength of 771.4 N and without a post (Group 2) had a fracture strength of 627.2 N. Advance material with a Flexi-Flange (Group 5) had a fracture strength of 706.7 N and Advance material without a post (Group 6) had a fracture strength of 597.8 N. Ti-Core Natural had a significantly larger mean failure threshold for fracture than either Tytin silver amalgam or Advance core material. Tytin and Advance did not differ from each other. There was no statistical difference between Ti-Core Natural supported by a post and Ti-Core Natural without a post. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS. A Five Year Study of Fluoride Release for Four Composite Resins. Oral Health 1998;88(4):81-86. The purpose of this study was to record the fluoride released measured in parts per million (ppm) of four fluoride composite resins for five years. This study consisted of four groups with three specimens per group, for total of 12 specimens. Two composite resins with high viscosity, Ti-Core with titanium (Group 1) and Ti-Core Natural (Group 2) were core materials and the other two resins studied were low viscosity post cements, Flexi-Flow cement with titanium (Group 3) and Flexi-Flow Natural (Group 4). The disks with diameter of 16.0 mm, thickness of 1.0 mm, and weight of 0.5 grams were placed into a glass jar with 40 mL deionized water. Fluoride concentration was measured with an Accumet 925 microprocessor meter and a solid-state fluoride ion-sensitive electrode. The data was reported in parts per million. Fluoride release from the disk was measured at the following time intervals; day 1, day 7, day 14, day 21, day 30, day 45, day 60, day 90, day 180, day 365 (1 year), 1.5 years, 2 years, 2.5 years, 3 years, 3.5 years, 4 years, 4.5 years, and 5 years were (ppm): Group 1: 2.77, 3.07, 2.43, 2.07, 2.91, 5.06, 2.91, 5.87, 11.97, 6.61, 1.35, 0.50, 0.37, 0.34, 0.28, 0.28, 0.23, and 0.19; Group 2: 1.94, 2.61, 1.36, 1.26, 1.08, 1.58, 2.35, 2.73, 6.10, 8.06, 4.16, 2.47, 1.79, 1.26, 1.05, 0.80, 0.55, and 0.58; Group 3: 0.31, 0.29, 0.22, 0.11, 0.15, 0.14, 0.16, 0.15, 0.25, 0.26, 0.15, 0.10, 0.16, 0.15, 0.15, 0.18, 0.13, and 0.12; Group 4: 0.69, 0.36, 0.24, 0.20, 0.18, 0.17, 0.15, 0.18, 028, 0.29, 0.32, 0.11, 016, 0.17, 0.13, 0.13, 0.14, and 0.12. Fluoride releases were analyzed using repeated measures analysis of variance (RMANOVA) for the individual weekly measurements and for the cumulative measurements. A one-way analysis of variance (ANOVA) followed by the Student-Newman-Keuls (SNK) pairwise multiple comparisons test was used to compare the average weekly release. All results were considered statistically significant if p < 0.05. The ANOVA showed that average weekly release differed significantly across groups (p < 0.0001). The SNK multiple comparisons test showed that mean average weekly release for Ti-Core with titanium did not differ


from Ti-Core Natural, and that Ti-Core with titanium and Ti-Core Natural differed significantly from both Flexi-Flow Natural and Flexi-Flow with titanium, which were not different from one another. Ti-Core with titanium (Group 1) and Ti-Core Natural (Group 2) released statistically greater amounts of fluoride than Flexi-Flow with titanium (Group 3) and Flexi-Flow Natural (Group 4). The fluoride released from these fluoridated resin composites are similar to reported ranges of other fluoride releasing dental restoration materials. Huget E. Compressive Profiles of Resin Composite Core Materials. J Dent Res 1998;77[Abstract 219]:133. This study focused on the modulus of elasticity of Ti-Core™(Essential Dental Systems, Inc.) and Fluorocore™ (L.D.Caulk). Young’s modulus (E) was measured by axial compression of 0.6 x 1.2 cm-specimens. Prior to testing, the specimens were aged in 100% R.H. at 37º C for either one, seven, or 28 days. Strain values for calculation of E were measured by relative platen displacement. Data was subjected to a two-way ANOVA (material & day). The effect of material on the property was significant (p< 0.002), the effects of specimen age (p< 0.004) and material x specimen age (p< 0.350) was not significant. Mean Young’s modulus are presented in the table. Material & Specimen Age Young’s Modulus (GPa) Ti-Core, 1 d 16.3 ± 0.80 Ti-Core, 7 d 16.7 ± 0.93 Ti-Core, 28 d 16.7 ± 1.08 FluoroCore, 1d 6.7 ± 0.63 FluoroCore, 7 d 6.2 ± 0.33 FluoroCore, 28 d 6.8 ± 0.67 This study concluded that Ti-Core displayed the highest stiffness. Reagan S, Frutts T, Van Brunt C, and Ward C. (University of Oklahoma, College of Dentistry, Oklahoma City, Oklahoma). Effects of Cyclic Loading on Selected Endodontic Post Systems. J Dent Res 1998;77[Abstract 222]:133. The effects of repetitive reciprocal lateral forces during the fatigue testing of selected post and core systems was investigated. After removal of the pulp tissue from fifty extracted human mandibular premolars, each premolar was imbedded in an acrylic filled PVC ring. The coronal portion of each tooth was removed, leaving a flat horizontal surface just above the CEJ. The teeth were divided into five groups of ten. These groups consisted of the following post and core systems: PA = Parapost (Whaledent) with amalgam (Dispersalloy, Dentspy/Caulk) core; PT = Parapost with resin composite (Ti-Core, Essential Dental Products) core; RA = Roane post (Moyco) with amalgam core; RT = Roane post with resin composite core; and CP - cast metal post & core (Olympia). Post space for the prefabricated posts were then prepared

according to the manufacturer’s recommendations. The preparations for the cast post and cores were done in a uniform and conservative fashion. All posts were cemented with zinc phosphate cement. The cores were of a uniform height and all walls were parallel to the long axis of the tooth. After storage in water, each specimen was placed in a unique testing machine developed by the authors which subjected the specimen to repetitive forces (10-lb) alternating from a buccal and lingual direction until a lateral movement of 0.0025 inches was detected by a transducer contacting the surface of the core. This criteria was selected to represent an initial failure. The results were recorded. Since two of the groups failed the statistical normality test, a non-parametric statistical test was used to analyze the data (Kruskal-Wallis one way ANOVA). The mean number of cycles prior to failure were (Standard Deviation): PA = 5513 (6033); PT = 13554 (14261); RA = 7316 (7574); RT = 12011 (7351); CP = 6174 (6422). Although groups using the resin composite material exhibited a higher mean number of cycles prior to failure the statistical analysis indicated that there was no statistically significant difference between the different groups of post and cores. Murdoch HG, Scrabeck JG, and Dhuru VB. (Marquette University School of Dentistry, Milwaukee, Wisconsin). Shear Bond Strength of Four Resin-Based Core Materials. J Dent Res 1998;487[Abstract 222]:174. The purpose of this study was to compare the bonding to dentin of four resin-based core materials. A total of 40 non-carious extracted permanent teeth were randomly distributed into 4 groups of 10 teeth each. The groups were: (1) FluoroCore (Dentsply L.D. Caulk Division, Milford, DE); (2) Den-Mat Core Paste (Den-Mat Corp., Santa Maria, CA); (3) Bis-Core (Bisco, Inc., Schaumburg, IL); (4) Ti-Core (EDS, Inc., Hackensack, NJ). Teeth were placed in acrylic mounting fixtures and occlusal surfaces sanded flat (600 grit) to which samples were bonded. Dentinal surfaces were conditioned, primed, and bonded according to the respective manufacturer’s directions. Bonding agent for Ti-Core was not specified by the manufacture, and Prodigy (Kerr Corp., Glendora, CA) was used with this material. Cylindrical specimens of core materials were cured directly on dentinal surfaces using a plastic sleeve with an internal diameter of 5 mm, and a height of 4 mm. Specimens were stored in 37°C water for 72 hours, and shear debonding load was determined using an Instrom machine at a crosshead speed of 0.51 mm/min (Trial 1). Debonded teeth were resurfaced by removing approximately 250 microns of dentin with 600 grit emery paper and a second set of 10 specimens each were prepared, and tested with corresponding materials (Trial 2). Mean shear bond strength values were ([(in MPa (SD)] Trial 1. FluoroCore 9.8 (2.4), Den-Mat 8.2 (2.0), Bis-Core 9.7 (3.0), and Ti-Core 9.5 (1.5). Trial 2: FluoroCore 6.6 (1.3), Den-Mat 7.6 (4.3), Bis-Core 10.1 ((3.3), and


Ti-Core 8.3 (3.2). ANOVA and Tukey multiple layer test were used to analyze the data. It was concluded that no significant difference existed among the shear bond strengths of the four core materials studied. 1998 CRA Dental Product Buying Guide.CRA-Clinical Research Associates Newsletter. 1998;22(1):2&4. Products which were highly rated after clinical field trials: Ti-Core- Excellent overall grade & purchase indicated Al-Jasser AMO, Al-Ateeq K, Vowles RW, Jandt KD. Mechanical Properties of an Experimental Glass-Silica-Titanium Composite Hybrid. J Dent Res 1998;77(Abstract #71):640. Matsumura et al. (J Dent Res 71, 1992) previously studied the mechanical properties of a titanium -polymethacrylate composite (Ti filler content 70-80 % by weight). To determine whether mechanical properties of a glass/silica filled two-paste anterior/posterior composite could be improved through the incorporation of fine Ti particles (diameter 1-3 µm) we measured the diametral tensile strength and the fracture toughness of three types of composites. 1. The original composite (control group), 2. As type 1 but containing 5% wt/wt of Ti particles and 3. As type 2 but Ti particles treated with 4-META in order to promote Ti-resin bonding. Ten specimens of each group were tested in a standard diametral tensile strength test and a fracture toughness test using a single-edge notched sample design. All specimens were stored for 24 hours in water (37ºC) prior to testing. The diametral tensile strength increased significantly after incorporation of Ti treated with 4-META, (p=0.004) as tested by ANOVA. A significant increase of fracture toughness was also observed between the control group and the other two groups (p=0.015). Diametral Fracture Tensile Toughness Strength (MNm-3/2) (MPa) Control, Group 1 45.5 ± 7.4 0.94 ± 0.03 Group 2 47.2 ± 1.4 1.20 ± 0.06 Group 3 49.3 ± 1. 6 1.23 ± 0.01 The tie lines in the table indicates values within non-significant differences (Scheffe’s test). Hence They conclude that the incorporation of fine Ti particles treated with 4-META into conventional composites may improve some mechanical properties. This abstract demonstrates that the addition of small quantities of titanium filler particles ( ie. 5% wt/wt) can affect the mechanical properties of composite material dramatically. Here, Group 2 and Group 3 are statistically greater than the control, Group 1. This study confirms that Ti-Core, and Flexi-Flow with their titanium reinforcement can result in a more superior and stronger composite.

(Please see page 5 of this section for the compressive and diametrel tensile strength paper entitled: “Compressive and diametral tensile strength of titanium reinforced composites” Journal Esthetic Dentistry. 1992;4:50-5.) Mardirossian G, Bonilla E, Caputo AA. Fracture Toughness of Various Core Build-up Materials. J Dent Res 1998;77(Abstract #339):674. Prefabricated endodontic dowels have various occlusal configurations to retain core build-up materials. The retention mechanisms usually have shapes that include stress concentrating elements. It is important that core materials possess sufficient fracture toughness to resist these stresses. The purpose of this investigation was to compare the fracture toughness of several newer core materials with amalgam. Five core build-up materials were tested: a) glass ionomer (Ketac- Molar), b) resin-modified glass ionomer (Vitremer), c) titanium-reinforced composite resin, fluoride (Ti-Core), d) composite resin, fluoride (Fluorocore), and e) amalgam (Tytin). Fracture toughness determinations were made using three-point flexure of beams with a central single-edge notch. The notch was standardized by use of a special mold into which each of the materials was condensed. Ten beams of each material were tested on an Instrom test machine. The maximum loads were determined from which the fracture toughness values (KIC) were calculated. The data were analyzed statistically using ANOVA and t tests. The ratios of the fracture toughness values for each of the materials to that of amalgam are as follows: a) Ketac-Molar - 0.48; b) Vitremer - 0.49; c) Ti-Core - 0.93; d) Flurocore - 1.09. All the differences relative to amalgam were statistically significant (p< 0.05). There was no significant difference in the KIC values for the glass ionomer based materials (Ketac-Molar and Vitremer) and both of these were significantly lower than Ti-Core and Fluorocore (p< 0.01). The titanium-reinforced composite resin, the composite resin with fluoride, and amalgam materials exhibited fracture toughness most likely to withstand the stressed generated during mastication. Bolhuis HPB, Feilzer AJ, De Gee AJ, Davidson CL. A Standardized Method to Test the Resistance to Fracture of Teeth Restored with a Core and Crown. J Dent Res 1998;77(Abstract #1333):798. Many research was executed to evaluated the resistance to fracture of endodontically treated teeth, restored with a post, core and crown. Most of these studies showed a wide standard error due to the variation in tooth shape and quality which makes it difficult to use such a setup for fatigue studies. The aim of this study was to develop a standardized test-setup to evaluated the resistance to fracture of teeth that are restored with a core with, or without , a post and a crown. A standard cylindrical master with the shape of an endodontically treated decapitated tooth was made in brass. This master was used to make standard preparations in bovine teeth using the Celay copy-milling machine. The prepared teeth were provided with a core. Four materials were


used; Ti-Core and Photo-core (resin composite materials), Ketac-molar (traditional glass-ionomer material) without post, Duralay and a burnout post (Parapost) to make a conventional gold casted core. After this part of the restoration, the teeth were prepared again by using a second master with the shape of a standard crown preparation. This preparation is ending in 2 mm sound dentin (Ferrule rule). Casted crowns with a standard shape were cemented with Ketac-Cem on the prepared teeth. At least 24 hours, the crowns were loaded under a 45 and 90 degree angle until fracture. In the control group, teeth without any core were used. These crowns got their retention only from the 2 mm axial dentin (Ferrule effect). Weibull’s statistic was degree loading. Statistical significant differences could be demonstrated in resistance to fracture between a casted gold core, a resin composite core and a glass-ionomer cement core which showed the lowest strength value. In ongoing research teeth restored using this standardized method will be exposed to in-vitro occlusal loading to evaluate the influence of fatigue. Here, please note that Ti-Core (titanium reinforced composite core material) was statistically greater in fracture strength than the glass-ionomer (Ketac-molar) and statistically similar to Photo-core (resin composite material). Cohen BI, Pagnillo MK, Deutsch AS, Musikant BL. Wytrzymalosc na pekanie trzech maaterialow do odbudowy zrebu koronowego z wkladem lub bez wkladu koronowo-korzeniowego z przcietym trzonem. Stomat Wspolczesna 1998;5(2):126-131. (Paper published in Poland’s Stomatologia Wspólczesna (Polish) Fracture strengths of three core restorative materials supported with or without a prefabricated split-shank post) This study evaluated the resistance for the core materials supported with or without a post. Ti-Core material supported by a split-shank (Flexi-Flange) post recorded statistically significantly higher fracture resistance than all other core materials supported by a post (Tytin silver amalgam and Advance material). An artificial crown was not used to cover the cores, but the results of this study are important because the strength of the cores were tested in a worst case scenario situation. The aim of this study was to compare the fracture strengths of three restorative materials, a lanthanide reinforced composite (Ti-Core Natural), a silver amalgam (Tytin), and a hybrid glass ionomer (Advance), supported by either a multi-tiered, threaded split-shank post (Flexi-Flange) or with a dentin spur without a post. A total of 60 recently extracted single-rooted human teeth were divided into six groups of 10. All groups were stored at 100% humidity at room temperature for 1 week before testing. Each specimen was placed in a special jig at a 45-degree angle to the buccolingual axis and subjected to a crosshead speed of 0.63 cm/minute until failure. The results were; 1) Ti-Core without a post 230.8±38.8, 2) Ti-Core with post 213.0±49.5, 3) Tytin amalgam with post 172.8±31.5, 4) Tytin amalgam without post 140.8±57.0, 5) Advance with post 158.3±24.4, 6) Advance without post

133.9±45.5. Two-way analysis of variance followed by the Newman-Keuls pairwise multiple comparisons test were used to compare the results. There was a statistically significant difference between core materials (p < 0.001), but not regarding post conditions. Ti-Core Natural material had a significantly larger mean failure threshold for fracture than either Tytin silver amalgam or Advance material and the latter two core materials (Tytin and Advance) do not differ from each other. There was no statistical difference between Ti-Core material supported by a post and Ti-Core material supported without a post. Cohen BI, Pagnillo MK, B. Penugonda, E. Hittelman. Comparison of the microhardness for five core build-up materials. Oral Health 1999;89(10):25-33. The purpose of this in vitro study was to investigate and compare the Barcol microhardness of five different core build-up materials. This study was divided into five groups with 10 specimens per group (specimens were fabricated with a thickness of 1 mm and a diameter of 20 mm). The groups consisted of two resin composites (Ti-Core Natural and Ti-Core with titanium), one resin-modified glass ionomer (Vitremer), and two conventional glass ionomers (Ketac-Silver and GC Miracle Mix). All specimens were stored in a 100% humidity environment for 24 hours before testing the microhardness. Each specimen had five microhardness readings taken with a Barcol microhardness Indentor. A one-way ANOVA was applied to the data followed by a Scheffe multiple range comparison test. Results were considered significant if p<0.05. The one-way ANOVA illustrated that there was a significant difference for microhardness of each group. The Scheffe multiple range comparison test demonstrated that Ti-Core Natural (Barcol value of 116) core build-up material was significantly different than Ti-Core with titanium (Barcol value of 112.1) core build-up material and both were significantly greater than Vitremer (Barcol value of 88.04) core build-up material. All specimens for the conventional glass ionomers (Ketac-Silver and GC Miracle Mix) failed during testing and therefore, no Barcol value could be obtained. The composite resin Ti-Core Natural and Ti-Core with titanium core build-up materials have a greater resistance to being deformed from masticatory forces than the resin-modified glass ionomer and conventional glass ionomers (where conventional glass ionomers because of their weak physical properties resulted in no Barcol microhardness values obtained Cohen BI, Pagnillo MK, Musikant BL, Deutsch AS, Cofrancesco G. Pilot study comparing the effects of bonding systems on the torsional resistance of a titanium reinforced core material. J Prosthet Dent 1999;82:277-280. The purpose of this pilot study was to investigate the effects of multi-step bonding agents on the torsional resistance of a titanium reinforced composite core material (Ti-Core core material). This in vitro study


was divided into four groups with 10 specimens per group. A total of 40 recently exacted human molars with their crowns removed were placed into acrylic blocks. Only multi-step bonding systems were used (AllBond-2, ScotchBond Multi-Purpose, Tenure A&B and the control with no bonding agent). The specimens were prepared according to manufacturer’s instructions. The control group was etched with a 37.5% phosphate acid. All cores were fabricated with Ti-Core titanium core material using hard copper bands No. 1 as the matrix. The cores were applied to the tooth surface with Ti-Core core material and allowed to cure for one hour before being placed into a 100% humidity for one week. The test specimens were placed in a special jig and a clockwise torsional force applied. The torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorded in inch x ounce. Krushal-Wallis non-parametric rank test followed by a Bonferroni-adjusted pairwise multiple Mann-Whitney tests were used to test for statistical significance and were considered significant if p < 0.05. The torsional values (inch x ounce) were as follows: AllBond-2, 28.04, ScotchBond Multi-Purpose, 26.77, Tenure A&B, 30.34 and the control group had a value of zero. The statistical analysis revealed that each bonding system differed significantly from the control group, but did not differ from one another. The use of a bonding agent increases a core’s resistance to torsional forces. The lack of a bonding agent dramatically reduces the resistance of a restoration’s torsional stress. Shear Bond Strength of a Titanium Reinforced Core Material After Using Multi- and Single-Step Bonding Agents. Cohen BI, Pagnillo MK, Musikant BL, and Deutsch AS. J Prosthet Dent 1998;80:307-10. This in vitro study evaluated the shear bond strength of a titanium reinforced cores (Ti-Core) bonded with five multi-step bonding systems (ScotchBond Multi-Purpose, OptiBond, All Bond-2, Tenure, and ProBond) and five single-step bonding systems (Single-Bond, OptiBond Solo, One-Step, Tenure Quik, and Prime & Bond 2.1). The experiment was divided into 10 groups with 10 specimens per group. The shear bond strengths were evaluated after 24 hours on a MTS universal testing machine with a crosshead speed of 6.35 mm/min. A two-way ANOVA showed that Bisco’s All Bond-2 and One-Step recorded the highest means and differed significantly from each of Den-Mat’s systems (Tenure A&B and Tenure Quik), Kerr’s systems (OptiBond and Opti-Solo), and Caulk’s systems (ProBond and Prime & Bond 2.1). Caulk’s ProBond and Prime & Bond 2.1 bonding systems had the lowest mean and differed from the three other brands. Den-Mat’s Tenure A&B and Tenure Quik bonding systems and Kerr’s OptiBond and Opti-Solo bonding systems did not differ from one another. The “single-step” bonding agents did not produce an improvement in shear bond strengths. The wide range of shear bond strength reported for the “single-step” systems appeared

to indicate that these bonding systems are technique sensitive. Post and core combinations tested for retention. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Dental Abstracts 1998;43(5):250. Retention of posts is a major factor in successful treatment involving endodontic therapy and post and core restoration. This study compared the retention of three endodontic posts cemented with five different materials and compared them with a control. Specimens were 160 recently extracted single-rooted teeth. Crowns removed at the cemento-enamel junction and teeth were divided into 16 groups of 10. One group was treated with a Flexi-Post No. 2 dowel without cement (control). The appropriate post hole was made according to manufacturers instructions for the three stainless steel dowels tested: Flexi-Post, EDS’ AccessPost, and ParaPost. Five groups of each dowel were used to test each of the cements: Flexi-Flow Natural (resin composite), ZOP (zinc phosphate), Advance (hybrid glass ionomer), Duet (hybrid glass ionomer), and Ketac-Cem (glass ionomer). Specimens were tensile tested until the post was removed. Results were analyzed by post and by the post/cement interactions. The Flexi-Post dowel had the highest mean retention rate, followed by EDS’ AccessPost. The Flexi-Post dowel cemented with Flexi-Flow Natural had the highest retentive value (303.91 pounds). The ParaPost dowel cemented with Duet had the lowest value (21.23 pounds). Flexi-Flow cement had the highest total mean retention, followed by ZOP, Advance, Ketac-Cem, and Duet. Retention was influenced significantly by both the post and cement used. Post-related differences did not remain constant when different cements were used. Combinations of posts and cements demonstrated significant differences in retention. The Lazy Dentist’s Guide to Excellence: 101 Efficiency Tips and Secret Forms of a Top-Producing Dental Practice. Wahl MJ. 1999;2:62. When a core is necessary, Ti-Core is extremely strong and helpful. The Effects of Bonding Agents on Torsional Resistance of Post and Cores. Deutsch AS, Cohen BI, Pagnillo MK, Newman I, Musikant BL. J Dent Research. (IADR Abstract #1713) 1999;78:320. The purpose of this study was investigate the effects of bonding of the torsional resistance of two passive post designs (EDS’ AccessPost and the ParaPost dowels) with a titanium reinforced core (Ti-Core) utilizing four different bonding conditions (AllBond-2, ScotchBond Multi-Purpose, Tenure A&B, and without a bonding agent). Torsional resistance is an important factor in the long-term survivability of an endodontically treated tooth, but there are no studies measuring the torsional value of a prefabricated post with a composite core. This in vitro study was divided into eight groups with 10 specimens per group. A total of 80 recently exacted single-rooted human teeth with their crowns removed at


the cementoenamel junction were used. Stainless steel EDS’ AccessPost No. 2 (Essential Dental Systems) and the equivalent stainless steel ParaPost No. P-44-6 (Whaledent/Coltene) endodontic dowels were used. All endodontic post holes were prepared according to manufacturer’s recommendations. Placement of the bonding agent was performed as per manufacturer’s instructions. The two control groups were etch with a 37.5% phosphoric acid (ScotchBond acid etchant) for seconds and then rinsed with distilled water. The cores were allowed to cure for one hour before trimming and being placed into acrylic blocks (Formatray). The test specimens were then placed into a 100% humidity environment for a week before testing. The test specimens were then placed in a special jig and a custom vise was tighten onto the core. The torsional force was then measured on a Lebow 1102-200 torque transducer apparatus (Eaton Corp.) and the force was recorded in inch x ounces on a Hewlett Packard 7015B X-Y recorder. A two-way analysis of variance (ANOVA) was used to compare mean torque across posts and bonds and to examine the interaction between post and bond. All results were considered statistically significant if p < 0.05. The torsional values ranged from 53.31 inch x ounce (ParaPost/ScotchBond Multi-Purpose) to 72.31 inch x ounce (EDS’ AccessPost/ScotchBond Multi-Purpose). The two-way ANOVA showed no significant interaction between post and bond system and also showed no significant differences between posts or between bonding agents. The bonding agents used in this study have no significant effect on the torsional resistance of a post and core restoration. There was no significant different in the torsional resistance between the EDS AccessPost post system and ParaPost post system. An dowel bonded with ScotchBond Multi-Purpose produced the highest torsional resistance (72.31 inch x ounce).

Cohen BI, Pagnillo MK, Musikant BL, Deutsch

AS. Bond Strength of Ti-Core using Multi- and Single-Step Bonding Agents. J Dent Research. (IADR Abstract #383) 1999;78:153. The purpose of this in vitro study was to evaluate the

shear bond strength of titanium reinforced cores (Ti-Core) bonded with five multi-steps bonding systems (ScotchBond Multi-Purpose, OptiBond, AllBond-2, Tenure A&B, and ProBond) and five single-step bonding systems (Single-Bond, OptiBond Solo, One-Step, Tenure Quik, and Prime & Bond 2.1). This experiment was divided into 10 groups with 10 specimens per group. A total of 100 recently exacted human molars were used. All molars had their crowns removed at the cementoenamel junction with a diamond disk and were then placed into acrylic resin blocks (Formatray). All specimens were etched according to manufacturer’s recommendation. Tooth surfaces were prepared with a bonding system according to the manufacturer’s instructions. Test cylinders of Ti-Core material (Essential Dental Systems) were prepared having a height of 12.7 mm and a diameter of 4.57 mm. These cylindrical cores

were then bonded to the prepared dentin with Ti-Core composite material and allowed to cure for one hour. The specimens were then placed into a 100% humidity environment for 24 hours before being tested. The shear bond strengths were evaluated on a MTS universal testing machine with a crosshead speed of 6.35 mm/min until failure. A two-way ANOVA followed by a Bonferroni-adjusted multiple pairwise contrasts were used to compare results and considered statistically significant if p < 0.05. The results were as follows: Multi-Purpose systems (5.28 MPa), AllBond-2 system (8.02 MPa), OptiBond system (5.48 MPa), Tenure A&B system (6.22 MPa), and ProBond system (3.88 MPa), Single-Bond system (6.01 MPa), One-Step system (5.06 MPa), OptiBond Solo (3.45 MPa), Tenure Quik system (4.14 MPa), and Prime & Bond 2.1 system (1.59 MPa). The two-way ANOVA showed that Bisco’s AllBond-2 and One-Step recorded the highest means and differed significantly from each of Den-Mat’s systems (Tenure A&B and Tenure Quik), Kerr’s systems (OptiBond and Opti-Solo), and Caulk’s systems (ProBond and Prime & Bond 2.1) which had the lowest mean and differed from the three other brands. Den-Mat’s Tenure A&B and Tenure Quik bonding systems and Kerr’s OptiBond and Opti-Solo bonding systems did not differ from one another. The 3M’s Single-Bond system (6.01 MPa) was not significantly higher than the 3M’s multi-step system (5.28 MPa). However, when 3M’s systems were excluded from the analysis, there was a significant difference between bond types (p < 0.0116) where “multi-steps” had larger mean shear bond strength then “single-step” systems. The “multi-step,” AllBond-2 (8.02 MPa) bonding system yielded a greater bond strength and the “single-step” Prime & Bond 2.1 (1.59 MPa) bonding system has the lowest bond strength compared to all other systems studied. The “multi-steps” had a greater shear bond strength compared to the “single-step” systems. The use of the “single-step” bonding systems did not produce higher bond strengths than those of “multi-step” bonding systems, with the exception of 3 M’s Single-Bond system, which was not significantly higher than 3 M’s ScotchBond Multi-Purpose system.

Esthetics Post Placement. Essential Dental Systems, Inc. Contemporary Esthetics 1998;2(6)30-32. The first and most important function of the post is not esthetics, but the ability to support the restoration with the greatest long-term stability. The split-shank design of the Flexi-family (Flexi-Post, Flexi-Flange, Flexi-Overdenture) of post creates an architecture that integrates the needs of a supportive post and high retention with those of the root, minimal insertional stresses, and the even distribution of functional stresses. To make this solid foundation esthetics, the manufacture has developed tooth-colored, long-term (at least 5 years), fluoride-releasing composite cements and core materials, namely Flexi-Flow Natural and Ti-Core Natural. Together with an opaquing layer these products mask the color of the metal post and improve


its esthetics. In addition, Ti-Core and Flexi-Flow also come in grey (reinforced with titanium) to differentiate from the lighter tooth structure when necessary. Effects of cyclic loading on selected post-and-core systems. Reagan SE, Fruits TJ, Van Brunt CL, Ward CK. Quintessence Int 1999;30:61-67. The purpose of this study was to evaluate the resistance of selected post-and-core systems to fatigue testing. A fatigue-testing machine and data acquisition software were developed for this in vitro test. Pulpless mandibular second premolares were treated with three different types of post-and-core systems:(1) two different prefabricated posts with amalgam cores (2) the same two prefabricated posts with composite cores (Ti-Core), and (3) cast post and cores, which served as the control group. The fatigue-testing machine applied alternating buccal and lingual forces to the core until lateral movement of 0.0025 inches (63.5 µm) was detected by a transducer contacting the surface of the core. This criterion represented initial cement failure. All of the post-and-core systems that were tested may be acceptable for endodontically treated teeth however, the groups using the resin composite core material exhibited higher number of cycles prior to failure and do to have the disadvantages of amalgam. (ie., 20-30 minutes before sufficient strength is achieved for preparation, concerns about mercury, discoloration of gingival tissue, and esthetic problems when certain all-ceramic crowns are used). Cyclic loading of Ti-Core vs. amalgam was found to be statistically similar. Ti-Core and Ti-Core Natural also have the advantage of long-term fluoride release. LA FUERZA DE FRACTURA DE TRES TIPOS DE MATERIALES PARA EL MUÑON EN COMBINACION CON TRES ESPIGAS ENDODONTIACALES DISTINTAS. Cohen BI, Condos S, Deutsch AS, Musikant BL. R. Cent. Ci. Bioméd. Univ. Fed. Uberlândi. 1997;13(1):69-76. (Spanish text published in Brazil “Fracture strength for three different core materials in combination with three different posts”. ) The purpose for this study was to determine the fracture load for three different core materials supported by three different posts systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3x 3 factorial two-way analysis of variance (p<.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were: Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin 100.6; Parapost/Tytin, 134.6; Flexi-Post/Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and Parapost/Ketac-Silver, 37.7; The Titanium composite, Ti-Core, had the greatest fracture load values in all instances; the

silver-filled glass-ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the Parapost had the least. Both the Flexi-Post and the Vlock post have large bulky heads with many vertical and horizontal grooves, apparently facilitating the locking of the core material into the post. Retencja trzech rodzajów wkladów koronowokorzeniowych cementowanych za pomoca pieciu róznych cementów. Cohen BI, Pagnillo M, Newman I, Musikant BL, Deutsch AS. Stomatologia Wspólczesna 1999;Supp 1:24-29. (Article printed in Polish: Retention of three endodontic posts cemented with five dental cements.) The purpose of this study was to compare the retentive values of three different posts (Flexi-Post, EDS’ AccessPost, and ParaPost) cemented with five different cements (Flexi-Flow, zinc phosphate, Advance, Duet, and Ketac-Cem) plus a control group that consisted of a Flexi-Post No. 2 dowel without cement. A total of 160 recently extracted human single-rooted teeth with crowns removed at the cemento-enamel junction were divided into 16 groups with 10 samples per group. Post holes were prepared according to manufacturers' instructions. Posts were then cemented with either Flexi-Flow, zinc phosphate, Advance, Duet, or Ketac-Cem cements. Each sample was placed into a specialized jig and on a tensile testing machine with crosshead speed of 0.638 cm/min applied until failure. A two-way analysis of variance and Newman-Keuls multiple range comparison tests were performed for all cemented groups. A one-way analysis of variance and a Student-Newman-Keuls multiple range comparison test was performed only for the groups with the Flexi-Post dowel, this included the no cement condition. Results were consider to be statistically significant if p<0.05. The Flexi-Post dowel with Flexi-Flow Natural cement obtained the highest retentive value of 303.91 pounds. ParaPost dowel with Duet cement had the lowest retention value of 21.23 pounds. The Flexi-Post dowel had higher mean retention than did EDS’ AccessPost or ParaPost dowels, and EDS’ AccessPost dowel was higher than ParaPost dowel. Flexi-Flow cement had the highest overall mean retention followed, in decreasing order by zinc phosphate, Advance, Ketac-Cem, and Duet cements. Flexi-Post dowel was the most retentive post studied with values ranging from 303.91 pounds with Flexi-Flow Natural cements to 150.93 pounds without cement. Flexi-Flow cements had a higher overall mean retention than other cements studied. Penugonda B, Cohen BI, Pagnillo MK, Schulman A, Hittelman E. Torsional Forces on Crowns supported by Post-Core Restorations. J Dent Res 2000;79:546 (Abstract 3223). The purpose of this in vitro study was to investigate the effect of torsion on a crown supported by a titanium-reinforced composite core material (Ti-Core core material) and three different endodontic post system (Flexi-Post, EDS’AccessPost and ParaPost). This study was divided into three groups with 10 specimens per


group. A total of 30 recently extracted human single-rooted (incisors) teeth with their crowns removed at the cementoenamel junction were used. Post-hole preparations were created following manufacturer’s instructions. The post-holes were prepared to a depth of 10 mm. All posts were cemented in place using Flexi-Flow cement. Scotchbond Multi-Purpose bonding agent was used as the bonding system for all groups. All cores were fabricated with Ti-Core with titanium core build-up material using hard copper bands as the matrix. The Ti-Core core build-up material was placed and allowed set for one hour before being shaped and trimmed with 0.5 mm shoulder and beveled on tooth using diamond burs. Polyvinyl siloxane (PVS) impressions of the teeth were taken to fabricate metal crowns on epoxy dies. Polished metal crowns were cemented with zinc phosphate cement. The test specimens were then placed into acrylic blocks and stored in 100% humidity for 1 week before being tested. The test specimens were placed in a special jig and a clockwise torsional force was applied. The torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorder in inch x ounces. A one-way ANOVA followed by a Student-Newman-Keuls (SNK) and Scheffe comparison tests were performed and results were considered significant if p<0.05. Results of the mean torque loading was as follows; Group 1, Flexi-Post 162.2 ± 52.2 in x oz, Group 2, EDS’ AccessPost 77.2 ± 30.3 in x oz, and Group 3, ParaPost 60.9 ± 28.4 in x oz. The results of the ANOVA revealed a significant difference p<0.001. The SNK and Scheffe comparison test revealed that the Flexi-Post group had significantly greater resistance to torque loading than the EDS AccessPost and ParaPost groups, which were statistically similar to each other. It was concluded that post design has an effect on torsional resistance of a crown supported by a titanium reinforced core build-up and post. The active threaded split-shank design of the Flexi-Post dowel offers greater resistance to torsional loading than the passive posts studied. Deutsch AS, Cohen BI, Pagnillo MK, Newman I, Musikant BL. Post-head Retention of Two Core Materials Using Three Post Designs. J Dent Res 2000;79:546 (Abstract 3222). The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a

centrix syringe. The post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS’ AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Cohen BI, Pagnillo MK, Newman I, Musikant BL, and Deutsch AS. Retention of Four Endodontic Posts Cemented with Composite Resin Cements. AGD (Gen Dent) 2000;48(3):320-324. The purpose of this in vitro study was to test and compare the retentive values of the Cerapost ceramic post cemented with Universal Post Cementation Kit II system (Brasseler USA) to the split-shanked Flexi-Flange, ExactaCast (a burnout/cast post), ExactaCast with grooved dentin, and ParaPost dowels, all cemented with Flexi-Flow Natural cement (Essential Dental Systems). This study was divided into 5 group with 10 samples per group. A total of 50 recently extracted human single-rooted teeth with their crowns removed at the cementoenamel junction (CEJ) were used. The post-hole for each group was made according to manufacturer’s instructions. A post-hole length of 10 mm was used to standardized the post-hole length for all groups studied. One of the ExactaCast groups had their post-holes grooved with a retentive grooving drill. All groups except the Cerapost dowel group were cemented with a lanthanide reinforced fluoride releasing Bis-GMA based composite cement, Flexi-Flow Natural (FF) according to manufacturer’s instructions. For all groups, the cement was allowed to set for 1 hour before


specimens were placed into acrylic blocks. The test specimens were then stored in a 100% humidity environment at room temperature for 24 hours before being tested. The tensile strength test was performed using a 810 MTS testing machine (Material Testing System) with a crosshead speed of 0.638 cm/minute until failure. Failure occurred when the post was removed from the tooth or with post head breakage. One-way analysis of variance (ANOVA) followed by a Student-Newman-Keuls (SNK) multiple comparisons test was used to compare the mean retention. Results were consider to be statistically significant if p < 0.05. The retention of all groups (in pounds) was as follows; Flexi-Flange/FF 270.4 ±34.3, ExactaCast grooved/FF 90.6 ±21.3, ExactaCast/FF 63.9 ±18.9, ParaPost/FF 70.3 ±19.5 and Cerapost/Universal cement 23.4 ±7.8. ANOVA revealed a significant difference between groups (p<0.0001). The SNK test showed that the Flexi-Flange post recorded highest level of retention followed by ExactaCast with grooved dentin walls which were greater than ParaPost dowel and ExactaCast without grooved dentin walls. The Cerapost with Universal cement system had statistically lower retention than all other groups studied. From the results of this study the following conclusions were drawn; the threaded, split-shank design of the Flexi-Flange (270.4 pounds) offers the greatest retention. The serrated design of the ExactaCast cast post in conjunction with grooved dentin walls offers the greatest retention of all passive post designs studied with a retention value of 90.6 pounds. The smooth wedge-shape design of the Cerapost ceramic post is the least retentive post design with a retentive value of 23.4 pounds. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of Three Endodontic Posts Cemented with Five Dental Cements. Practical Periodontics & Aesthetic Dentistry 1999;11(4):452. The purpose of this study was to compare the retentive values of three different posts (Flexi-Post, EDS’ AccessPost, and ParaPost) cemented with five different cements (Flexi-Flow, zinc phosphate, Advance, Duet, and Ketac-Cem) plus a control group that consisted of a Flexi-Post No. 2 dowel without cement. A total of 160 recently extracted human single-rooted teeth with crowns removed at the cementoenamel junction were divided into 16 groups with 10 samples per group. Post holes were prepared according to manufacturers' instructions. Posts were then cemented with either Flexi-Flow, zinc phosphate, Advance, Duet, or Ketac-Cem cements. Each sample was placed into a specialized jig and on a tensile testing machine with crosshead speed of 0.638 cm/min applied until failure. A two-way analysis of variance and Newman-Keuls multiple range comparison tests were performed for all cemented groups. A one-way analysis of variance and a Student-Newman-Keuls multiple range comparison test was performed only for the groups with the Flexi-Post dowel, this included the no cement condition. Results were consider to be statistically significant if p<0.05. The Flexi-Post dowel with Flexi-Flow Natural cement

obtained the highest retentive value of 303.91 pounds. ParaPost dowel with Duet cement had the lowest retention value of 21.23 pounds. The Flexi-Post dowel had higher mean retention than did EDS’ AccessPost or ParaPost dowels, and EDS’ AccessPost dowel was higher than ParaPost dowel. Flexi-Flow cement had the highest overall mean retention followed, in decreasing order by zinc phosphate, Advance, Ketac-Cem, and Duet cements. Flexi-Post dowel was the most retentive post studied with values ranging from 303.91 pounds with Flexi-Flow Natural cements to 150.93 pounds without cement. Flexi-Flow cements had a higher overall mean retention than other cements studied. Combe EC, Shaglouf AMS, Watts DC, Wilson HNHF. Mechanical properties of direct core build-up materials. Dental Materials 1999;15:158-165. This study measured mechanical properties of a diverse group of materials used for direct core build-ups. Materials included were: Coradent (Chemically cured resin composite core material with particulate ceramic filler), Duralloy (High copper admixed silver amalgam), Ketac Silver (Silver cement), Prisma APH (VLC hybrid resin composite), and Ti-Core (Chemically cured resin composite core material reinforced with titanium). Findings show that Ti-Core has both a strong compressive and diametral tesile strength. The authors note, the present data are similar to published figures for Ti-Core, but not for Coradent. B Penugonda, E Hittelman, Brett I. Cohen, and Mark K. Pagnillo. Barcoll Hardness of Five Core Build-Up Materials. International Symposium on Advanced Materials with Biomedical Applications 1999;Poster 37. The main objective of this study was to evaluate the surface hardness of five core build-up materials using a Barcoll hardness tester. Core build-up materials require a degree of hardness as a property to resist forces applied immediately during preparation and mastication. Ten specimens of each material, group 1 Ti-Core Natural, group 2 Ti-Core w/Titanium, group 3 Vitremer, group 4 Ketac-Silver and group 5 Miracle Mix were made according to manufacturer’s instructions. Each specimen (made from molds with a diameter of 20mm and a thickness of 1mm) was allowed to set for ten minutes and then placed in a 100% humidifier for 24 hours. A total of 50 specimens were subjected to a Barcoll hardness test. The mean Barcoll hardness values were; Ti-Core Natural 116.0±1.18, Ti-Core w/ Titanium 112±1.95, Vitremer 88.04±2.45, Ketac-Silver and Miracle Mix failed during testing, therefore no values were obtained for these two groups. Data was subjected to a statistical analysis including one way ANOVA and it was concluded that there was a significant difference in hardness (P<0.05) for each material, which could be related to chemical composition differences. Cohen BI, Pagnillo MK, Newman I, Musikant L, Deutsch AS. Pilot study of the cyclic fatigue characteristics of five


endodontic posts with four core materials. J Oral Rehabil 2000;27:83-92. This pilot study concerned the cyclic fatigue of five different endodontic post systems. (EDS’ AccessPost, Flexi-Flange, Flexi-Post, ParaPost and Vlock with four different core materials (Tytin Silver amalgam, Ti-Core, Ketac-Silver and G-C Miracle Mix). In vitro cyclic fatigue was performed using a fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 lbs. was applied to each post and core combination for a test configuration of 4,000,000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way ANOVA was used to compare groups. All posts/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4,000,000 test cycle without failures. All post /core samples with Ketac-Silver failed before the 4,000,000 test cycle test cycle configuration, all as a result of core failures. All post/core samples with G-C Miracle Mix failed in a similar way. The Newman-Keuls multiple comparison test illustrated that Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Similar fatigue test results are found in the literature. Gateau P, Sabek M, Dailey B. Fatigue testing and microscopic evaluation of post and core restorations under artificial crowns. J Prosthet Dent 1999;82:341-7. This in vitro study compared the mechanical resistance of 3 core materials (silver amalgam, composite, or glass ionomer) under masticatory conditions. Industrially fabricated teeth were used and a total of 75 specimens were divided into 3 groups of 25 specimens. Titanium root canal posts were placed, followed by core buildups in amalgam, composite, or glass ionomer. Teeth were prepared for full cast crowns and the crowns were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator cyclically loading the teeth with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. Teeth were sectioned and observed macroscopically and microscopically to determine the rate of defects for each material. Observed defects were verified with the Kruskal-Wallis test. The 3 core material were ranked with the Tukey multiple comparison test. Significant differences of mechanical behavior were found for the 3 materials. At P<.01, silver amalgam was significantly superior to composite and glass ionomer. Composite was significantly superior to glass ionomer. Cores fabricated with amalgam had the lowest rate of defects when tested under artificial crowns. Glass ionomer, when used as a core material under artificial crowns, showed the highest rate of defects after an instantaneous load of 400 N for a 1,500,000 repetition cycle. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of a core material supported by

three post head designs. J Prosthet Dent 2000;83(6):624-628. The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS’ AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Cohen BI, Penugonda B, Pagnillo MK, Schulman A, Hittelman E. Torsional resistance of crowns cemented to composite cores involving three stainless steel endodontic post designs. J Prosthet Dent 2000;84(1):38-42. The purpose of this in vitro study was to investigate the effect of torsion on a crown supported by a titanium-reinforced composite core material (Ti-Core core material) and three different endodontic post system (Flexi-Post, EDS’ AccessPost and ParaPost). This study


was divided into three groups with 10 specimens per group. A total of 30 recently extracted human single-rooted (incisors) teeth with their crowns removed at the cementoenamel junction were used. Post-hole preparations were created following manufacturer’s instructions. The post-holes were prepared to a depth of 10 mm. All posts were cemented in place using Flexi-Flow cement. Scotchbond Multi-Purpose bonding agent was used as the bonding system for all groups. All cores were fabricated with Ti-Core with titanium core build-up material using hard copper bands as the matrix. The Ti-Core core build-up material was placed and allowed set for one hour before being shaped and trimmed with 0.5 mm shoulder and beveled on tooth using diamond burs. Polyvinyl siloxane (PVS) impressions of the teeth were taken to fabricate metal crowns on epoxy dies. Polished metal crowns were cemented with zinc phosphate cement. The test specimens were then placed into acrylic blocks and stored in 100% humidity for 1 week before being tested. The test specimens were placed in a special jig and a clockwise torsional force was applied. The torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorder in inch x ounces. A one-way ANOVA followed by a Student-Newman-Keuls (SNK) and Scheffe comparison tests were performed and results were considered significant if p<0.05. Results of the mean torque loading was as follows; Group 1, Flexi-Post 162.2 ± 52.2 in x oz, Group 2, EDS’ AccessPost 77.2 ± 30.3 in x oz, and Group 3, ParaPost 60.9 ± 28.4 in x oz. The results of the ANOVA revealed a significant difference p<0.001. The SNK and Scheffe comparison test revealed that the Flexi-Post group had significantly greater resistance to torque loading than the EDS’ AccessPost and ParaPost groups, which were statistically similar to each other. It was concluded that post design has an effect on torsional resistance of a crown supported by a titanium reinforced core build-up and post. The active threaded split-shank design of the Flexi-Post dowel offers greater resistance to torsional loading than the passive posts studied. Musikant BL, Cohen BI, Pagnillo MK, and Deutsch AS. Pilot Study of Torque Resistance for a Ti-Core Composite Core Using Different Bonding Agents. J Dent Res 2000;79:546 (Abstract 3221). The purpose of this in vitro experiment was to test and compare the effects of three multiple-step bonding agents (All Bond-2, Scotchbond Multi-Purpose, and Tenure A&B) and a control group (no bonding agent), on the torsional resistance of a titanium reinforced composite core material (Ti-Core). This experiment was divided into four groups with 10 specimens per group. A total of 40 recently extracted human molars were used. All crowns were removed at the cementoenamel junction (CEJ) with a diamond disk leaving a smooth, flat surface that would not hinder the core rotational movement. The teeth were then placed into acrylic blocks. All test specimens were etched according to the manufacturer’s instructions with the

etching agent provided in the bonding kit. The tooth surfaces were prepared with the bonding systems according to the manufacturer’s instructions. The control group was etched with a 37.5% phosphoric acid gel. All cores were fabricated with Ti-Core with titanium composite material using hard No. 1 copper bands as the matrix. The cores were bonded to the tooth surface with a small amount of Ti-Core material and allowed to cure for one hour before being placed into 100% humidity environment for one week. A clockwise torsional force was applied using a Lebow 1102-200 torque transducer apparatus and the loads were recorded on a Hewlett-Packard 7015B X-Y recorder in units of inch x ounces then converted in Newton x meter (Nm). A one-way analysis of variance (ANOVA) was used to compare the three bonding systems and results were considered statistically significant if p<0.05. The results were as follows; All Bond-2, 0.1980 ±0.0663 Nm; Scotchbond Multi-Purpose, 0.1890 ±0.1149 Nm; and Tenure A&B 0.2142 ±0.1021 Nm. The control group obtained a value of zero due to all specimens failing without recording a value during testing. The one-way ANOVA found no significant difference between the three bonding systems (p=0.84). All bonding systems failed as a result of adhesive failure between the bonding agent and tooth surface with no core material failures being observed. Based on the results of this pilot study, the following conclusions were made; the use of a bonding agent increases the resistance of a titanium reinforced composite core (Ti-Core) to torsional forces. There is no difference between the type of multi-step bonding systems used in this torsional study. Pagnillo MK, Cohen BI, Newman I, Musikant BL, and Deutsch AS. Retention of Four Endodontic Post Designs Cemented with Composite Resin Cements. J Dent Res 2000;79:546 (Abstract 3220). The purpose of this in vitro study was to test and compare the retentive values of the Cerapost ceramic post cemented with Universal Post Cementation Kit II system (Brasseler USA) to the split-shanked Flexi-Flange, ExactaCast (a burnout/cast post), ExactaCast with grooved dentin, and ParaPost dowels, all cemented with Flexi-Flow Natural cement (Essential Dental Systems). This study was divided into 5 group with 10 samples per group. A total of 50 recently extracted human single-rooted teeth with their crowns removed at the cementoenamel junction (CEJ) were used. The post-hole for each group was made according to manufacturer’s instructions. A post-hole length of 10 mm was used to standardized the post-hole length for all groups studied. One of the ExactaCast groups had their post-holes grooved with a retentive grooving drill. All groups except the Cerapost dowel group were cemented with a lanthanide reinforced fluoride releasing Bis-GMA based composite cement, Flexi-Flow Natural (FF) according to manufacturer’s instructions. For all


groups, the cement was allowed to set for 1 hour before specimens were placed into acrylic blocks. The test specimens were then stored in a 100% humidity environment at room temperature for 24 hours before being tested. The tensile strength test was performed using a 810 MTS testing machine (Material Testing System) with a crosshead speed of 0.638 cm/minute until failure. Failure occurred when the post was removed from the tooth or with post head breakage. One-way analysis of variance (ANOVA) followed by a Student-Newman-Keuls (SNK) multiple comparisons test was used to compare the mean retention. Results were consider to be statistically significant if p < 0.05. The retention of all groups (in pounds) was as follows; Flexi-Flange/FF 270.4 ±34.3, ExactaCast grooved/FF 90.6 ±21.3, ExactaCast/FF 63.9 ±18.9, ParaPost/FF 70.3 ±19.5 and Cerapost/Universal cement 23.4 ±7.8. ANOVA revealed a significant difference between groups (p<0.0001). The SNK test showed that the Flexi-Flange post recorded highest level of retention followed by ExactaCast with grooved dentin walls which were greater than ParaPost dowel and ExactaCast without grooved dentin walls. The Cerapost with Universal cement system had statistically lower retention than all other groups studied. From the results of this study the following conclusions were drawn; the threaded, split-shank design of the Flexi-Flange (270.4 pounds) offers the greatest retention. The serrated design of the ExactaCast cast post in conjunction with grooved dentin walls offers the greatest retention of all passive post designs studied with a retention value of 90.6 pounds. The smooth wedge-shape design of the Cerapost ceramic post is the least retentive post design with a retentive value of 23.4 pounds. Cohen BI, Penugonda B. Use of inductively-coupled plasma-emission spectroscopy and mercury vapor analyses to evaluate elemental release from a high-copper dental amalgam: A pilot study. J Prosthet Dent 2001;85(4):409-412. The main purpose of this study was to evaluate the elemental leaching for Tytin dental amalgam for both mercury vapor and elemental analysis (silver, copper, tin and mercury) when placed in deionized water for two months. The use of dental amalgam as a direct restorative material has been a subject of controversy for the last two decades. Concerns have been growing over dental amalgams use and its potential safety due to leakage of elements such as mercury, copper, tin and silver. Mercury compounds and elemental mercury vapor can be neurotoxic and immunotoxic when it reaches higher levels in human body. The WHO standard for occupational exposure to mercury vapor -TLV is 50 µg/m3 for 8 hours in 24 hour day and 150 µg/m3 for 15 minutes (short time value). Two capsules of Tytin amalgam were triturated (one for the precipitate and liquid analysis and the other for the mercury vapor analysis) and stored in a polypropylene tube with 10 mL of deionized water for sixty days at room temperature. The amalgam pellet was then

removed (after 60 days) and rinsed with deionized water. The resulting liquid was separated from a precipitate and two separate analyses were run; 1) on the liquid without any precipitate and 2) on the precipitate. Elemental analysis for Copper (Cu), Tin (Sn), Mercury (Hg) and Silver (Ag) were determined by inductively coupled plasma emission spectroscopy with a Perkin-Elmer P2000 spectrometer. Mercury vapor analysis were performed everyday for 60 days using a Jerome 431-X vapor analyzer. The maximum amount of copper 80µg, silver 2.6 µg, mercury 15µg and tin 550 µg was found in the precipitate. The maximum amount of mercury vapor released was 67 µg/m3 per day. There was a significant amount of elemental leaching and mercury vapor release from the Tytin Amalgam over a sixty day period. Cohen BI, Condos S, Deutsch AS, Musikant BL. Porównanie wytrzymalosci na naprezenia tnace wiazania róznych materialow zlozonych zawierajacych tytan, stosowanych razem z materialem laczacym i cementow szklanojonomerowych. Stomat.Wspótczesna 2000;7(1):33-37. (Comparison of the shear bond strength of a titanium composite resin material with dentinal bonding agents versus glass ionomer cements. Published in Polish). This study compared the in vitro shear bond strength of an autopolymerizing composite resin system (CR) (Ti-Core) with two third-generation dentinal bonding agents (DBA) (Tenure and Scotchbond 2) to glass ionomer cements (GIC) (Ketac-Silver, GC Miracle Mix, and Ketac-Cem). The experiment was divided in five groups. The shear bond strengths were evaluated on a universal testing apparatus at three different intervals; 15 minutes, 24 hours, and 7 days. Statistically, (two-way analysis of variance), the shear bond strengths from the greatest to least were: Ti-Core with Tenure DBA> Ti-Core CR with Scotchbond 2 DBA> Ketac-Silver GIC, GC Miracle Mix GIC> Ketac-Cem GIC. There were no differences in shear bond strengths according to time, and no interactions between groups and time. The shear bond strengths for Tenure DBA with Ti-Core CR were two and a half to three times greater than the silver-filled glass ionomers, Ketac-Silver GIC and GC Miracle Mix GIC. Tenure DBA with Ti-Core CR also had consistently greater shear bond strengths than Scotchbond 2 DBA with Ti-Core CR, and this trend is in agreement with similar research. 1. A statistical analysis revealed that the shear bond strengths from the greatest to the least were: Ti-Core CR with Tenure DBA> Ti-Core CR with Scotchbond 2 DBA> Ketac-Silver GIC, GC Miracle Mix GIC> Ketac-Cem GIC. 2. There were no differences in the shear bond strengths with time and no evidence of interactions between groups and time. 3. The shear bond strengths of Tenure DBA with Ti-Core CR were two and a half to three times greater than for the silver-reinforced glass ionomer cements Ketac-Silver GIC and GC Miracle Mix.


Abed H, Razzoog ME, Lang BR, Yaman P. Masking Ability of PROCERA AllCeram copings using deferent core substructure materials. J Dent Res 2000;79:179 (Abstract 281). PROCERA ALLCeram copings (Procera Sandvik AB, Sweden) are made from densely sintered high purity alumina. While the eventual restoration exhibits excellent esthetic properties questions remain about the translucency and ability to mask different underlying materials. The purpose of this study was to analyze the differences in masking ability of densely sintered high purity alumina when different core build-up materials were used. Ten Coping discs were manufactured from this material with uniform wall thickness of 0.6 mm. A brass mold with one hole 10mm in diameter and 2 mm deep fabricated by the University of Michigan Engineering Laboratories were used to produce core build-up material discs of 10-mm diameter and 2 mm thickness Five different types of Core Build-up materials were used. These materials were: Amalgam (Tytin, Kerr, U.S.A.), Gold (Meracast, Ney, U.S.A.), Titanium (Noble Biocare, Gotheborg, Sweden), Ti-Core Grey, (Essential Dental Systems, S. Hackensack, NJ, U.S.A.), Ti-Core N (Natural), (Essential Dental Systems). The CIE ZL* a* b* colour co-ordinates were measured under Lab and Yxy modes for measuring chromaticity and color deviation using a colorimeter (Minolta Chroma Meter CR-300, Minolta Inc., Osaka, Japan.) with a reading head 3.0 mm diameter. Three readings were taken for each one of the ten Procera All-Ceram disc samples when placed on top of each five different core build-up materials. The mean was calculated and used as a single value for each sample in the statistical analysis. The mean measurements for all ten samples were as follows: (* First row L*, Second row a*, Third row b*) Gold Titanium Ti-Core Grey Ti-Core Natural Amalgam Under Lab Under Yxy Under Lab Under Yxy Under Lab Under Yxy Under Lab Under Yxy Under Lab Under Yxy 80.603 58.930 77.116 51.117 76.611 51.080 78.771 54.676 79.326 57.246 1.023 0.345 -0.548 0.332 -0.790 0.332 -0.061 0.337 -0.088 0.338 14.451 0.359 9.798 0.351 9.698 0.366 12.091 0.355 12.595 0.356 The L* a* b* values of the PROCERA AllCeram core material measured on five different core build-up materials exhibited no statistically significant differences when the coping wall thickness was uniform. Here, Ti-Core Grey and Ti-Core Natural were statistically similar to titanium, gold, and amalgam cores. Galvan RI, Robertello FJ, Lynde TA. In vitro comparison of fluoride release of six direct core materials. J Prosthet Dent 2000;83:629-33. Fluoride has been shown to deter caries and has been incorporated into core build-up materials. This study compared the fluoride released by 6 commercially available fluoride-releasing core materials over a 89-day

testing period. Ten specimen disks (9 for Corestore) of each of the 6 core materials were fabricated, finished, measured, and immersed in deionixed water in individual polystyrene jars. The jars were stored in a humidor at 37ºC between test periods. At the same time each day for 7 consecutive days, then at 14, 22, 28, 59, and 89, the fluoride release was measured from each specimen disk in parts per million by testing the storage medium. The data was analyzed using 1-way ANOVA and Tukey-Kramer multiple comparison tests. Five of the 6 core build-up materials tested showed an initial high concentration of fluoride release during the first day and gradually tapered throughout the 89-day testing period. The results of this study showed that some core materials, over time, release more fluoride than others (second greatest fluoride release). Ti-Core, titanium reinforced composite resin was among the groups producing high levels of cumulative fluoride release. Please Note: This study demonstrates 89-day testing, for additional fluoride results data please refer to: Cohen BI, Pagnillo M, Musikant BL, Deutsch AS. A Five Year Study of Fluoride Release for Four Composite Resins. Oral Health 1998;88(4):81-86. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. The Effects of Eugenol and Epoxy-resin on the strength of a hybrid composite resin. J Endodon 2002;28(2)79-82. The compatibility of the chemistries regarding different dental materials (root canal sealer and composite core build-up restoratives) is an important factor for a successful restoration. However, there are limited studies in the literature demonstrating eugenol’s effect on the gross physical characteristics (compressive and diametral tensile strength) for a classical hybrid composite resin. No studies are known in the literature regarding the interaction of epoxy-resin based root canal sealers with composite resins. The aim of this in vitro study was to determine the effects on compressive and diametral tensile strength for a classical chemical cure composite resin (Henry Schein Composite Anterior-Posterior dental restorative, Port Washington, NY) when in contact with either; eugenol or an epoxy-resin in a variety of situations: 1) added during mixing of a composite resin before curing, 2) vapor exposure to cured samples and 3) specimens placed directly (after curing). The experiment was divided into two parts; part one, compressive strengths (CS) and in part two diametral tensile (DT) strength. This experiment was divided into seven groups with 10 specimens per group. In groups 1-3, specimens were affected by Eugenol U.S.P. (Roth International, Chicago, Ill) ; specimens of groups 4-6 were affected by EZ-Fill (Essential Dental Systems, S, Hackensack, NJ) ; and the seventh group served as a control group. The CS and DT were evaluated on a 810 MTS universal testing machine with a cross-head speed of 0.25 inches per minute (0.635 cm/min). Results were CS (psi), DT(psi); group 1 CS 0, DT 0; group 2 CS 29050 + 5413, DT 4063 + 465; group 3 CS 27951 + 3302, DT 4401 + 820; group


4 CS 25353 + 2490, DT 4052 + 496; group 5 CS 28441 + 5736, DT 3897 + 597; group 6 CS 27504 + 4272, DT 4146 + 449; group 7 (control) CS 26466 + 2853, DT 4218 + 549. One-way ANOVA analysis was performed on groups 2 through 7 and a result was statistically significant if P < 0.05. Only the addition of eugenol during mixing with the composite resin (directly before curing) resulted in specimens that did not achieve a full cure (0 psi). There were no significant differences among the groups (2 through 7) with respect to either CS (P = 0.17) and DT (P = 0.39). Group 1 (mixed directly with eugenol) was found to be statistically different from groups 2 through 7. In conclusion, eugenol dramatically affects the strength of a composite resin during mixing where EZ-Fill’s epoxy-resin does not. All other groups where cured samples were measured resulted in strengths similar to that of the control. Cohen BI, Penugonda B. Evaluation of the Elemental Release for Tytin High-Copper Dental Amalgam. J Den Res (Abstract 1538B), 2001;80:276. The main purpose of this study was to evaluate the elemental leaching for Tytin (Kerr Corp. Romulus, Mich.) dental amalgam for both mercury vapor and elemental analysis (silver, copper, tin and mercury) when placed in deionized water for two months. The use of dental amalgam as a direct restorative material has been a subject of controversy for many years. Concerns have been growing over the use of dental amalgam and its potential safety due to leakage of elements such as mercury, copper, tin and silver. Mercury compounds and elemental mercury vapor can be neurotoxic and immunotoxic when the mercury concentration reaches dangerously high levels in the human body. The WHO standard for occupational exposure to mercury vapor -TLV is 50 µg/m3 for 8 hours in 24 hour day and 150 µg/m3 for 15 minutes (short time value). Two capsules of Tytin amalgam were triturated for 10 seconds (one for the precipitate and liquid analysis and other for the mercury vapor analysis) and stored in a polypropylene tube with 10 mL of deionized water for sixty days at room temperature. The amalgam pellet was then removed and rinsed with deionized water. The resulting liquid was separated from a precipitate with the use of filtration paper and two separate analyses were run: (1) on the liquid without any precipitate and (2) on the precipitate. Elemental analyses for copper (Cu), tin (Sn), mercury (Hg) and silver (Ag) were determined by inductively coupled plasma emission spectroscopy with a Perkin-Elmer P2000 spectrometer. Mercury vapor analyses were performed daily for 60 days using a Jerome 431-X vapor analyzer. The maximum amount of copper 80 µg, silver 2.6 µg, mercury 15 µg and tin 550 µg was found in the precipitate. The liquid had 9.6 ppm of copper, 0.19 ppm of silver, 0.031 ppm of mercury and 0.28 ppm of tin. The maximum amount of mercury vapor released was 67 µg/m3 per day {Day 1, 31 µg/m3, day 4, 67 µg/m3, day 60, 6 µg/m3; average

weekly mercury vapor week 1, 41 µg/m3, week 2, 30 µg/m3, week 3, 28 µg/m3, week 4, 19 µg/m3, week 5, 16 µg/m3, week 6, 11 µg/m3, week 7, 10 µg/m3, week 8, 6 µg/m3}. There was a significant amount of elemental leaching for copper, silver, mercury and tin and mercury vapor release from the Tytin amalgam over a sixty day period. Musikant BL, Cohen BI, Volovich Y, Deutsch AS. Retention of a Flexi-Flange post with bonded Ti-Core cores. J Den Res (Abstract 1774), 2001;80:257. The use of dentinal bonding agents has achieved wide acceptance in dentistry. However, there are limited studies on their retention of a post with a core bonded to tooth structure using various dentinal bonding agents. The purpose of this study was to determine the retentive values of a Flexi-Flange post (Essential Dental Systems, Inc. S. Hackensack, NJ) with a Ti-Core Natural core (Essential Dental Systems, Inc.) using various dental multi-step bonding agents (Tenure Multi-step (Den-Mat Corp. Santa Maria, Calif), All-Bond 2 (Bisco, Inc. Itasca, Ill.) and 3m Scotchbond (3M Dental Products Division St. Paul, Minn.)) compared to a control where no bonding agent was used. The experiment was divided into 3 groups and a control with 10 specimens per group. The retentive strengths were evaluated after 24 hours on a 810 MTS universal testing machine with a crosshead speed of 0.638 cm/min. The results were; Tenure 264.5 + 52.7 pounds, All-Bond 2 291.4 + 42.1 pounds, 3M Scotchbond 297.9 + 37.9 pounds and the control 270.4 + 34.3 pounds. A one-way ANOVA illustrated that none of the groups differed statistically from each other and from the control (P< 0.2448). The values for the retention of the Flexi-Flange/ Flexi-Flow/Ti-Core using various dentinal bonding agents ranged from a low of 264.5 pounds (Tenure) to a high of 297.9 pounds (3M Scotchbond) with a control (without bonding agent) of 270.4 pounds. All of the retention for the Flexi-Flange post resulted from the retention of the split-shank threaded portion (mechanical retention) of the post which mechanically engages the root canal. The phenomenon where mechanical retention is greater and more significant than chemical retention (from dentinal bonding agents) has been described previously in the literature. Purton DG, Love RM, Chandler NP. Rigidity and Retention of Ceramic Root Canal Posts. Operative Dent 2000;25:223-227. CeraPost (1.2 mm coronal diameter, ceramic/tapering/smooth posts) and ParaPosts (1.25 mm stainless-steel, parallel/serrated posts) were tested for rigidity by means of a three-point bending test. To test retention in roots, ceramic posts were cemented using one of three protocols: (1) glass-ionomer cement, (2) silane coupling agent and composite resin cement, or (3) sandblasted post surface, silane coupling agent, and composite resin cement. Stainless-steel posts were cemented with composite resin. The tensile force required to dislodge the post, following four weeks of storage in water, was recorded. Data were compared


using Student’s t-test and Mann-Whitney U analysis. The stainless-steel, parallel/serrated posts cemented with composite resin were significantly more retentive than the smooth/tapering Cerapost. Bonilla ED, Mardirossian G, Caputo AA. Fracture Toughness of Various Core Build-Up Materials. J Prosthodon 2000;9(1):14-18. The purpose of this investigation was to compare the fracture toughness of several core materials. Fracture toughness determinations were made using 3-point flexure of beams with a central single-edge notch. the notch was standardized by the use of a special mold into which each of the materials was condensed. Ten beams of each material were tested on an Instrom test machine at a crosshead speed of 1.25 mm/min. the maximum lad were determined form which the fracture toughness values were calculated. The data was analyzed statistically using a variance and t test. The mean fracture toughness value in MN • m -3/2 were as follows: Tytin amalgam 1.521 ± 0.081, Ti-Core titanium reinforced composite with fluoride 1.409 ± 0.015, Vitremer resin-modified glass ionomer 0.747 ± 0.061, and Ketac-Molar glass ionomer 0.717 ± 0.071. Ti-Core titanium reinforced composite with fluoride and Tytin amalgam showed fracture toughness likely to withstand the stresses generated during mastication. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Retentive Properties of a Split-Shank Threaded Post with a Core Using Three Different Multi-Step Bonding Agents. Oral Health 2000;90(10):43-51. This study determined the retentive values of a Flexi-Flange post with a Ti-Core Natural core using various dental multi-step bonding agents (Tenure, All-Bond 2 and 3m Scotchbond) compared to a control where no bonding agent was used. The experiment was divided into 3 groups and a control with 10 specimens per group. The retentive strengths were evaluated after 24 hours on a 810 MTS universal testing machine with a crosshead speed of 0.638 cm/min. A one-way ANOVA illustrated that none of the groups differed statistically from each other and from the control ( P< 0.2448). The values for the retention of the Flexi-Flange/ Flexi-Flow/Ti-Core using various dentinal bonding agents ranged from a low of 264.5 pounds (Tenure) to a high of 297.9 pounds (3M Scotchbond) with a control (without bonding agent) of 270.4 pounds. All of the retention for the Flexi-Flange post resulted from the retention of the split-shank threaded portion (mechanical retention) of the post which mechanically engages the root canal. The phenomenon where mechanical retention is greater and more significant than chemical retention ( from dentinal bonding agents) has been described previously in the literature. Cohen BI, Pagnillo MK, Condos S, Musikant BL, Deutsch AS. Wlasciwosci retencyjne wkladów z przecietym trzpieniem, skróconych w czesci wierzcholkowej. Twój Przeglad Stomatologiczny 2000;3:40-43.

(Article Published in Polish: Retention properties of a split-shaft threaded post: Cut at different apical lengths.) The retention of the post to the root of an endodontically treated tooth is critical for a successful restoration. Modification of the post length to accommodate a specific clinical situation is common. This study compared the retention of No. 1 and No. 2 Flexi-Post restorations shortened apically form 1 to 5 mm with that reported for full-length control No. 1 and No. 2 Flexi-Post dowels. The experimental material was divided into 10 groups with 10 samples in each group. Retentive values were recorded in pounds with a universal testing machine. Analysis of variance with a Tukey-Student range, multiple comparison test showed no statistical differences from apical reductions of 1, 2, 3, and 5 mm including the full-length control Flexi-Post No. 1 system. With 4 mm of apical shortening statistically greater retention was recorded. No statistical differences resulted with apical reductions of 1 to 4 mm or with the full-length control Flexi-Post No. 2 system, but 5 mm of apical shortening caused significantly less retention. 1. There was no significant difference in retention of Flexi-Post No. 1 dowels between the control group and the groups shortened by 1, 2, 3, or 5 mm. 2. The No. 1 Flexi-Post system recorded a statistically significant increase (p<0.011) in retention for posts reduced by 4 mm. 3. There was no significant difference in retention for the Flexi-Post No. 2 system between the full-length control group and the groups shortened by 1, 2, 3, or 4 mm. 4. A statistically significant (p<0.001) difference in retention was observed for the Flexi-Post No. 2 dowel shortened by 5 mm and the remaining groups: The full-length control and 1, 2, 3, or 4 mm apical reductions. 5. Reducing the post shaft length to 4 mm for both the Flexi-Post No. 1 and No.2 dowels did not adversely affect the retention of the post. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Comparison of the flexural strength for six reinforced restorative materials. AGD (Gen Dent) 2001;49(5):484-488. Flexural strength (Kf) values are a key property that can be used by the dentist to predict a material’s clinical behavior under in vitro loading conditions. However, flexural strength values are obtained using a three-point bending configuration test, and this test method is complicated and requires extensive calculations and specialized jig apparatus to determine its value. This study calculated the flexural strength for six reinforced restorative materials and demonstrated that flexural strength values can be determined simply by using physical parameters (diametral tensile strength and Young’s modulus values) that are easily determined experimentally. The flexural strength (Kf) values were calculated for Ti-Core with titanium core material (group 1), Ti-Core Natural (group 2), Flexi-Flow with titanium composite resin cement (group 3), Flexi-Flow Natural (group 4), Ketac-Silver glass ionomer (group 5), and GC Miracle Mix glass ionomer (group 6). Values for flexural strength ranged from a


low of 17.2 MPa for GC Miracle Mix and 22.2 MPa for Ketac-Silver glass ionomers, to a high of 63.8 MPa for Ti-Core with titanium composite resin core material. A one-way ANOVA analysis demonstrated that there was a statistically significant difference between the two reinforced glass ionomers (Ketac-Silver and GC Miracle Mix) and other four composite resin materials (Ti-Core, Ti-Core Natural, Flexi-Flow and Flexi-Flow Natural) (p < 0.0001), with the composite resin being statistically stronger than the glass ionomers. There was no statistical differences between the Ti-Core and Flexi-Flow groups. The calculated values for flexural strength are similar to those obtained for Ti-Core and Ketac-Silver determined in literature using different flexural strength test methods. Therefore, this method of calculating the flexural strength using physical parameters such as, diametral tensile strength and Young’s modulus values to determine the flexural strength has been shown to be easily obtained with accurate results. Penugonda B, Cohen BI. Analysis of Mercury Vapor for Tytin Amalgam at different pH Levels. J Dent Res (Abstract 0160) 2001;80:546. The main purpose of this in vitro study was to evaluate the mercury vapor release for Tytin dental amalgam (Kerr Corp. Romulus, Mich.) when placed in three different pH media (pH 4, 7 and 10) for two months.

Three different pH buffers were used as the solutions for the experiment in order to approximate oral environment conditions from acidic to basic. The use of dental amalgam as a direct restorative material has been a subject of controversy for the last two decades. Concerns have been growing over dental amalgams use and its potential safety due to leakage of elements such as mercury, copper, tin and silver. Mercury compounds and elemental mercury vapor can be neurotoxic and immunotoxic when it reaches higher levels in human body. The WHO standard for occupational exposure to mercury vapor -TLV is 50 µg/m3 for 8 hours in 24 hour day and 150 µg/m3 for 15 minutes (short time value). Three capsules of Tytin amalgam were triturated (one for each pH solution) and stored in a polypropylene tube with 10 mL of a pH buffer (Fisher Scientific, Fairlawn, NJ; certified pH buffers of pH 4.0 + 0.01 @ 25°C (Cat. No. SB 101-500), pH 7.0 + 0.01 @ 25°C (Cat. No. SB 107-500), pH 10.0 + 0.01 @ 25°C (Cat. No. SB 115-500)) for sixty days at room temperature. Mercury vapor analysis were performed for 60 days using a Jerome 431-X vapor analyzer. Results were (Day 1, 2, 5, 6, 7, 8, 9, 13, 15, 16, 19, 20, 21, 22, 23, 26, 27, 28, 29, 30, 34, 35, 36, 37, 41, 43, 44, 47, 48, 49, 50, 51, 54, 55, 56, 58, 59, 60-- pH 10, 7, 4 (µg/m3 )): 287,27,35; 294,87,51; 185,82,156; 115,81,130; 118,56,122; 85,52,106; 84,59,89; 88,66,101; 81,65,100; 67,42,83; 56,52,75; 41,34,65; 47,39,56; 30,29,60; 37,36,53; 47,53,75; 26,28,35; 25,22,42; 12,23,34; 18,20,39; 20,25,35; 15,20,30; 15,18,34; 10,15,26; 18,20,39; 18,25,37; 13,17,27; 7,16,30; 12,17,34; 8,18,24; 3,13,24; 5,15,25; 10,16,22; 8,12, 24; 8,12,26;

9,11,35; 9,17,23; 8,10,25; Cumulative 1939, 1250, 2027. The cumulative mercury vapor release was the highest for pH 4 (2027 µg/m3 ) followed by pH 10 (1939 µg/m3 ) and pH 7 (1250 µg/m3 ). pH 10 had a burst effect where more mercury vapor was released sooner in the first week than for pH 7 and pH 4. This effect did not last for pH 10 and after the second week the quantity of mercury vapor release was dramatically reduced. It should be noted, that at the end of the 60 day test period, the pH levels for the three different solutions were measured (with the amalgam pellet removed) and found to be exactly the same as compared to the beginning of the experiment. Thus, no chemical change in the pH buffers (pH 4, 7 and 10) were noted for each of the solutions. These findings may add to the concerns regarding the safety of dental amalgam. There was a significant amount of mercury vapor release in three different pH media from the Tytin Amalgam over a sixty day period. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Comparison of the Photoelastic stress properties for different post-core combinations. Oral Health 2001;91(10):63-72. This study compares two different core materials (Ti-Core and GC Miracle Mix) supported by two different endodontic post systems (Flexi-Post and Para-Post) for photoelastic stress distribution in an oblique loading condition with a 26 degree angle at 20 pounds. Four groups of post/core systems blocks of photoelastic materials were prepared with simulated endodontic canals (using a plastic that approaches the strength of dentin), and the specimens (photoelastic block/cemented post/core combinations) were then photographed in the unloaded and loaded states. Minimal stresses were observed for all post/core combinations in the unloaded state. The specimens prepared with the multi-tiered, Flexi-Post clearly distributed stress symmetrically and coronally in the loaded oblique state, while the specimens with the single tiered Para-Post showed asymmetrical apically and coronally stress patterns. Post/core combinations with Ti-Core composite were more stable than post/core combinations with GC Miracle Mix glass ionomer. The symmetric, even stresses for the Flexi-Post/core systems are more favorable than the asymmetric, uneven stresses for the Para-Post/core systems. Post/core combinations with Ti-Core a titanium reinforced composite are more stable and favorable than post/core combinations with GC Miracle Mix glass ionomer. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention values of post head design and core materials compared. Dental Abstracts 2000;45(6):270. The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and


Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS’ AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Comparison of torsional resistance for natural human teeth. Dentistry (UK) 2003;Jun:19-20. Torsional resistance of an endodontic restorative system is an important consideration for a long-term restoration. However, currently no studies have established the amount of torsional resistance necessary for a tooth reconstruction; no cut-off or threshold limit values for success or failure are known in the literature. This study determined the torsional resistance of the natural human teeth by investigating a possible correlation between teeth dimensions and their resistance to torsional force. This study also compares the torsional resistance of post-core components which make up a restoration from previously published studies. Three groups of 10 specimens per group were studied. A total of 30

recently extracted human single rooted (incisors) teeth were used. All teeth were measured and recorded at the cementoenamel junction (CEJ), buccolingually (B/L) and mesiodistally (M/D). The groupings were selected according to teeth dimension. The extracted teeth were mounted in acrylic resin blocks. Test specimens were placed into a special jig and a clockwise torsional force was applied. Torsional force was measured on a Lebow torque transducer and recorded on a Hewlett-Packard recorder measured in inch X ounces. A One-way analysis of variance (ANOVA) and SNK was used to test for statistical significance (P < 0.05). The torsional resistance values (inch X ounce) were: group 1; 33.97 + 9.20 ( B/L = 5 mm, M/D = 3-4 mm), group 2; 37.67 + 17.68 (B/L = 6 mm, M/D = 4-5 mm) and group 3; 76.15 + 33.71 (B/L = 7-8 mm, M/D = 5-6 mm). SNK revealed that group 3 had significantly greater resistance to torsional loading than groups 1 and group 2. Groups 1 and 2 were statistically similar to each other. The tooth dimensions have an effect on torsional resistance of the tooth. The torsional resistance of teeth with B/L = 7-8 mm and M/D = 5-6 mm are significantly greater than the torsional resistance of teeth with B/L = 5-6 mm and M/D = 3-5 mm. Are Ceraposts really this bad? Reality: The Reviews 2000;128:21-22.* This article reviewed three articles which have tested retention values of the Cerapost to answer the question - Are CeraPosts really this bad?: 1) Cohen BI, Pagnillo MK, Newman I, Musikant BL, and Deutsch AS. Retention of Four Endodontic Posts Cemented with Composite Resin Cements. AGD (Gen Dent) 2000;48(3):320-324. Upon critique of this article Flexi-Flange, a patented split-shank threaded post, was found be significantly more retentive than the passive CeraPost. 2) Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of a core material supported by three post head designs. J Prosthet Dent 2000;83(6):624-628. Upon critique of this article the CeraPost was found to have poor adhesion to core materials. Reality stated; it is obvious that metal-free posts should also have heads with macro-mechanical retention, similar to those on metal posts. Miracle Mix is obsolete and has no place in modern dentistry. 3) O’Keefe KL, Miller BH, Powers JM. In Vitro Tensile Bond Strength of Adhesive Cements to New Post Materials. International J Prosthodon 2000;13(1):47-51.Upon critique of this article, relating to the bond strength of resin three resin cements (Panavia 21, C&B Metabond and Bis-Core), Panavia 21 was found to have the highest bond strength (to metal as well as carbon-fiber). Reality does point out that; “Unfortunately, due to its anaerobic setting mechanism and especially with the addition of the ED Primers, it is difficult to use Panavia 21 when cementing post. There is always a danger it will begin to set at the bottom of the posthole before you can seat the post.”


*From Reality’s Publication, Reality: The Reviews 2000;128:21-22. Quintas AF, Giannini V, Muratore V, Neisser MP, Bottino MA. Effect of thermocycling on composite resin core retention to posts. J Den Res (Abstract 1255) 2001;80:192. Composite resin restorations can have their longevity affected by factors encountered in oral environment, such as thermal stress. However, the possible effect of thermal changes on composite resin cores is not well established. The aim of this study was to evaluate this variable on composite core retention to metallic posts. An acrylic mold was machined in order to fit a metallic post (Flexi-Post No. 2); at the coronal end of the post, a 3 mm diameter space was created to build-up the composite resin core (Ti-Core). Forty samples were divided into four groups. In Group A, no thermocycling was performed (control); last three were submitted to thermocycling in a temperature interval of 15 and 45° C (30 seconds each bath). Number of cycles in these groups was 1,500 cycles for Group B, 3,000 cycles for Group C and 6,000 cycles for Group D. Samples were subjected to tensile strength test in a MTS-810 machine (speed 0.5 mm /min) till core was dislodged or fractured. Means were subjected to Kruskal-Wallis statistical test, that revealed no significant difference among groups tested (p>0.05). By these results, authors concluded that composite core retention to post was not affected by thermal changes. Munoz CA, Jessop N, Dunn JR. Shear Bond Strength of Resin-based Core Materials to Adhesives with Activators. J Dent Res (Abstract 6030) 2001;80:605. It has been reported that one-bottle light cured DBA do not bond properly with resin-based self-cured core materials. New activators have been used with the DBA to help solve this incompatibility. This study evaluated the shear bond strength of 3 one-bottle systems with activators: Solo Plus + activator, (SP), Tenure Quick LC with activator (TQ), P & B NT + activator (PB) and One Step no activator (OS). Human molars were ground with 600-grit SiC paper to expose the dentin and assigned to 12 groups of 10 each. SP, and PB were mixed with activator, applied and CorePaste, Ti-Core Natural or CoreRestore, mixed and applied. TQ was applied, light cured, activator applied and same core materials applied. OS was applied, light cured and core materials applied. Specimens were incubated @ 37° C for 10 minutes and tested. A shear load was applied to the specimen at a crosshead speed of 1.0 mm/min and the bond strength expressed in MPa. A one-way ANOVA was used to determine the effect of bond strength on the one-bottle adhesives with activators (P>0.05). Materials SP TQ PB OS Mean SD Mean SD Mean SD Mean SD

CorePaste 25.20±4.09 17.32±1.78 8.92±1.78 27.25±7.75 Ti-Core Natural 22.17±2.36 20.25±3.07 9.18±2.11 31.85±3.54 CoreRestore 25.45±5.26 22.62±2.57 7.24±1.77 28.96±6.55 Results indicate that One Step light cured had the highest bond strength. Solo Plus cured had a higher bond strength that Prime & Bond self cured. There was no statistical difference in bond strength when each adhesive was compared to the three core materials. The clinical application of self cured resin-based core material is a viable alternative with the use of one-bottle adhesives with activators. Tachibana K, Kuroe T, Tanino Y, Satoh N, Ohata N, Sano H, and Caputo AA. Contraction Stress of Flowable and Hybrid Resin Composites for Build-ups. J Dent Res (Abstract 0652) 2001;80:608. Flowable resin composite is a relatively new material for fillings and build-ups. Lower filler load may result in larger shrinkage, but lower stiffness may allow larger flow during polymerization. Little is known about how those properties of flowable composites affect contraction stress. The purpose of this study was to photoelastically compare polymerization shrinkage stress of flowable and hybrid resin composites for build-ups. Photoelastic models of endodoctically treated molars were fabricated. The model configuration included four lateral walls but no post hole. The dimension of the cavity was approximately 4 mm X 5mm X 4mm. A flowable fast-set self-cured resin composite (Core-Flo, BISCO) and a dual-curable hybrid composite (DC Core, Kuraray) were used for build-up. Following conditions were tested; 1) Flowable chemical cure, 2) Hybrid chemical cure (polymerized in the absence of light), 3) Hybrid dual-cure (light-cured for 60 sec.). The stresses developed in the models were recorded photographically in the field of circular polariscope arrangement. Five specimens were examined for each condition and the mean values of the maximum fringe order was compared statistically. For all the conditions tested, the highest fringe order was developed at the line angles of the cavity floor. There was no significant difference in the highest fringe order between the dual-cured hybrid and flowable groups. However, the chemically cured hybrid group developed approximately one fringe order lower stresses compared with the other two groups and the difference was statistically significant. Fringes of higher order extended more occlusally in the dual-cured hybrid group. The differences in contraction stress were most likely to be a result of a combined effects of filler load, elastic modulus, setting time of the composites. The results indicate that flowable composite may not have advantage in contraction stress reduction over hybrid counterpart for build-ups. Musikant BL, Cohen BI, Deutsch AS. Current Trends in Post, Cores, and Restorative Crowns. Dentistry 2001;5:30-33. This article evaluated the recent developments in restorative dentistry, uncovering their pitfalls in critical areas such as;


post retention, insertional stress, distribution of functional stress, retention of core material. The Flexi-Post and Flexi-Flange post systems lead these categories by providing a maximum post retention of 220 lbs., minimal insertional stress by the use of a patented split-shank design, multi-tiered design for distribution of functional stress and, coupled with Ti-Core resin-composite core material, provide a long-term restoration. Bonilla ED, Mardirossian G, Caputo AA. Fracture Toughness of Various Core Build-Up Materials. J Prosthet Dent 2001;85(2):176. The purpose of this investigation was to compare the fracture toughness of several core materials. Five core build-up materials were tested: (1) Ketac-molar, glass ionomer, (2) Vitremer, resin-modified glass ionomer, (3) Ti-Core, titanium-reinforced fluoride releasing composite resin, (4) Fluorocore, composite resin with fluoride, and (5) Tytin, amalgam. Fracture toughness determinations were made using 3-point flexure of beams with a central single-edge notch. The notch was standardized by the use of a special mold into which each of the materials was condensed. Ten beams of each material were tested on an Instrom test machine at a crosshead speed of 1.25 mm/min. The maximum loads were determined from which the fracture toughness values (Klc)were calculated. The data was analyzed statistically using a variance and t test. The mean fracture toughness value in MN • m -3/2 were as follows: Tytin amalgam 1.521 ± 0.081, Ti-Core titanium reinforced composite with fluoride 1.409 ± 0.015, Vitremer resin-modified glass ionomer 0.747 ± 0.061, and Ketac-Molar glass ionomer 0.717 ± 0.071. Ti-Core titanium-reinforced composite and Tytin amalgam showed fracture toughness that can withstand the stresses generated during mastication. Cohen BI, Condos S, Musikant BL, Deutsch AS. Wytrzymalosc na zlamanie trzech roznych materialow, zastosowanych w polaczeniu z trzema rodzajami standardowych wkladów koronowo-korzeniowych, odbudowy zrebu koronowego. Compendium Stomatolgil 2000;4:13-15. (Paper published in Poland’s Compendium Stomatolgil (In Polish) Fracture strength for three different core materials in combination with three different endodontic posts.) The purpose for this study was to determine the fracture load for three different core materials supported by three different posts systems. The study was divided into nine separate groups, and each group comprised 10 samples. Specimens were placed in a special jig on a 45-degree angle, and the fracture load values were obtained using a universal testing machine a 3x 3 factorial two-way analysis of variance (p<.0408) was used to test the effects of core material and post type on the fractural resistance. Fracture load values (as measured in pounds) were: Flexi-Post/Ti-Core, 204.9; Vlock/Ti-Core, 218.8; Parapost/Ti-Core, 164.8; Flexi-Post/Tytin, 156.0; Vlock/Tytin 100.6; Parapost/Tytin, 134.6; Flexi-Post/Ketac-Silver, 69.4; Vlock/Ketac-Silver, 50.4; and

Parapost/Ketac-Silver, 37.7; The Titanium composite, Ti-Core, had the greatest fracture load values in all instances; the silver-filled glass-ionomer specimen, Ketac-Silver, had the least. The Flexi-Post and the microthread, Vlock, had the greatest fracture load values, and the Parapost had the least. Both the Flexi-Post and the Vlock post have serrated post heads with many vertical and horizontal grooves which facilitate retention. Cohen BI, Deutsch AS, Condos S, Musikant BL, Scherer W. Wytrzymalosc na sciskanie i rozciaganie materialow kompozytowych wzbogaconych tytanem. Twój Przeglad Stomatologiczny 2001;1:32-35. (Paper published in Poland’s Twój Przeglad Stomatologiczny (In Polish) Compressive and diametral tensile strength of titanium reinforced composites.) This article determines the compressive and diametral tensile strength of two titanium-reinforced composites (Bis-GMA based), Ti-Core and Flexi-Flow cem with titanium and compares their strengths to dentin and commercially available core materials and cements. In addition scanning electron microscope (SEM) photographs were taken of Ti-Core and Flexi-Flow cem with titanium. Compressive tensile loading was performed on a universal testing apparatus. Ti-Core and Flexi-Flow cem with titanium were measured to have compressive strengths of 41,132 and 41,876 psi and tensile strengths of 5,219 and 4,930 psi, respectively. Statistically (ANOVA, one-way analysis of variance), these titanium-reinforced composites are stronger in compressive and tensile strength than Ketac-Silver, Fleck's zinc cement, Durelon, Ketac-Cem, and GC Miracle Mix. Both titanium-reinforced composite materials approach the compressive and diametral tensile strengths of dentin (43,100 and 6,000 psi). SEMs revealed that the titanium was uniformly and homogeneously interspersed within the resin matrix of the material. 1. Compressive strength for the titanium-reinforced composite resins was statistically greater than any other group tested and very close to the strength of dentin. 2. Diametral tensile strength of the titanium-reinforced composite resins was statistically greater than any other group tested except for Den-Mat Core Paste. Their strengths were also very close to the strength of dentin. 3. SEM revealed that the titanium was homogeneously incorporated within the resin matrix of the composite resin. Cohen BI, Pagnillo MK, Deutsch AS, Musikant BL. Wytrzymalosc na pekanie trzech materialow do odbudowy zrebu koronowego z wkladem lub bez wkladu koronowo-korzeniowego z przecietym trzonem. Compendium Stomatolgil 2001;1:7-11. (Paper published in Poland’s Compendium Stomatolgil (In Polish) Fracture strengths of three core restorative


materials supported with or without a prefabricated split-shank post.) The aim of this study was to compare the fracture strengths of three restorative materials, a lanthanide reinforced composite (Ti-Core Natural), a silver amalgam (Tytin), and a hybrid glass ionomer (Advance), supported by either a multi-tiered, threaded split-shank post (Flexi-Flange) or with a dentin spur without a post. A total of 60 recently extracted single-rooted human teeth were divided into six groups of 10. All groups were stored at 100% humidity at room temperature for 1 week before testing. Each specimen was placed in a special jig at a 45-degree angle to the buccolingual axis and subjected to a crosshead speed of 0.63 cm/minute until failure. Two-way analysis of variance followed by the Newman-Keuls pairwise multiple comparisons test were used to compare the results. There was a statistically significant difference between core materials (p < 0.001), but not regarding post conditions. Ti-Core Natural material had a significantly larger mean failure threshold for fracture than either Tytin silver amalgam or Advance material and the latter two core materials (Tytin and Advance) do not differ from each other. There was no statistical difference between Ti-Core material supported by a post and Ti-Core material supported without a post. This study evaluated the resistance for the core materials supported with or without a post. Ti-Core material supported by a split-shank (Flexi-Flange) post recorded statistically significantly higher fracture resistance than all other core materials supported by a post (Tytin silver amalgam and Advance material). Caicedo R, Arias SE, Martinez SF, Nowogroder MW. Physical Properties Analysis of Two Different Posts Cemented with Lanthanide Reinforced Composite Cement. J Endodont 2001;27(3):232. The purpose of this study was to electrochemically measure coronal microleakage and tangential and compressive strengths of two types of post, one prefabricated (Cytco-Ti®) with a core build-up material reinforced with Lanthanide (Ti-Core® Natural, EDS) as reconstruction material. The second a type IV cast gold post with the ExactaCast® system (Burnout Post and Core System, EDS), cemented with Flexi-Flow Natural® (Lanthanide reinforce). Forty anterior teeth recently extracted were used and divided into two, 20 teeth groups. All teeth ere prepared with the step-back technique and then standardized at 17mm. Posts were prepared according to the technique set forth by manufacturers. They were tested as to microleadkage with electromechanical method after 20 days; then they were subdivided into four 10 teeth groups, taking 10 teeth of each group for the tangential strength test and the other 10 for the compressive strength test. Once the tests were completed 4 teeth were observed at SEM®and EDAX®. Results according to the Student and Kruskall Wallis Tests showed that gold post (ExactaCast) have better

physical properties than Cytco® posts as to leakage and tangential strength. At SEM, Flexi-Flow Cem.®-showed good adaptation to dentinal walls and to the post. Cohen BI, Musikant BL, and Deutsch AS. Abrasive Wear for five Composite Core build-up Materials. Oral Health 2002;92(5):87-93. The ability to resist mechanical wear (abrasion) is an important requirement of a dental composite restorative material. There are limited studies in the literature detailing composite core build-up abrasion. The purpose of this in vitro study was to conduct wear abrasion for five composite core build-up materials ( Ti-Core, Ti-Core Natural, Luxacore Automix (Dual), Build-It FR, and Core Paste Syringeable) using a wear testing apparatus with a silicone carbide counterface (Dura-Green Stones), measuring the loss of height or the depth of wear for each restorative material. Abrasive wear testing was performed with a testing apparatus incorporating a Healthco Dental Engine set at a speed of 1000 rpm’s. After abrasive wear testing was completed all depth of wear (loss of height) measurements were performed using an electronic caliper. The percentage decrease of depth of wear ranged from a low of 0.66% (Ti-Core) to a high of 11.38% (Build-it FR). Group/ Core Material Control (mm) Depth of wear (mm) % Decrease of Active treatment Depth of Wear 1- Ti-Core 2.575 + 0.027 2.558 + 0.015 0.66 % 2- Ti-Core Natural 2.583 + 0.023 2.539 + 0.022 1.70 % 3- Luxacore Automix 2.756 + 0.040 2.445 + 0.078 11.28 % 4- Build-it FR 2.918 + 0.057 2.586 + 0.098 11.38 % 5- Core Paste 2.639 + 0.020 2.457 + 0.042 6.89 % Note: The lowest percent decrease of depth of wear represents the best wear resistance. Two-way analysis of variance (ANOVA) with interaction term was used to compare mean abrasive wear resistance between treatment conditions and between composite materials and showed a significant interaction between materials and treatment (P < 0.0001). The mean for active treatment was significantly less than the control for Build-it, Luxacore and Core Paste. Active treatment and control did not differ for Ti-Core and Ti-Core Natural. Therefore, Both Ti-Core and Ti-Core Natural had the highest wear resistance and demonstrated statistically better wear than all the groups studied. Gateau P, Sabek M, Dailey B. In vitro fatigue resistance of glass ionomer cements used in post-and-core applications. J. Prosthet Dent 2001;86:149-55. Newer glass ionomer cements exhibit better mechanical properties than their conventional counterparts. However, there is concern about their use as a core material in post-and-core applications. This in vitro study evaluated the fatigue resistance of 2 new glass ionomer cements, Shofu Hi-Dense and Fuji IX GP, and compared their mechanical behavior as a core material under masticatory load with a silver-reinforced glass ionomer (ESPE Ketac-Silver) and a silver amalgam (Cavex Avaloy LC). A total of 100


commercial plastic teeth were divided into 4 groups of 25 specimens each. Titanium posts were placed in the prepared root canals, and cores were built up in amalgam, silver-reinforced glass ionomer cement, and the 2 new glass ionomer cements. The post-and-core specimens were prepared for full cast metal crowns, which were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator and cyclically loaded with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. The specimens were sectioned and observed microscopically to determine the number of defects (alterations) in each material. Observed defects were verified with the Kruskal-Wallis test, and the 4 core materials were ranked with the Tukey multiple comparisons test. The mean rank sum values of the defects were as follows: Cavex Avaloy LC Amalgam (16.75), Fuji IX GP (38.50), Shofu Hi-Dense (39.53), and ESPE Ketac-Silver (67.22). The amalgam alloy was significantly different (P<.05) from the others. Under the conditions of this study, the 2 new glass ionomer cements used as core materials showed a higher number of defects than amalgam. These results suggest that their fatigue resistance may be inadequate for post-and-core applications. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Photoelastic Stress Properties for different Post-Core Combinations. J Dent Res 2002;81(Abstract 3478):A-428. The use of photoelastic stress analysis has been shown to illustrate the stress distribution for various prefabricated and cast post systems. However, there are limited studies investigating the photoelastic stress distribution for endodontic post/core systems. The purpose of this study was to compare two different core materials; Ti-Core (Essential Dental Systems, Inc.) and GC Miracle Mix (GC Corporation), supported by two different endodontic post systems -Flexi-Post (Essential Dental Systems, Inc.) and Para-Post (Coltene/Whaledent) for photoelastic stress distribution in an oblique loading condition (20 pounds) at a 26 degree angle. Four groups of post/core systems blocks of photoelastic materials were prepared with simulated endodontic canals (using a plastic that approaches the strength of dentin); group 1, Flexi-Post No. 1 / Ti-Core, group 2, Flexi-Post No. 1 / GC Miracle Mix, group 3, Para-Post No. 1 equivalent / Ti-Core and group 4, Para-Post No. 1 equivalent/ GC Miracle Mix. Only stainless steel posts (Flexi-Post No.1- a split-shank, multi-tiered prefabricated post design and Para-Post- a passive single tiered prefabricated post) were used for this study and zinc phosphate cement was used to cement each post into its simulated canal preparation. Specimens (photoelastic block/cemented post/core combinations) were then positioned in a special jig on a universal testing machine (Model CETM 922MTT20/1, Comten Industries) with oblique loading at 20 pounds and color photographs of each specimen was recorded in the

unloaded and loaded states. Despite this gentle loading condition, the GC Miracle Mix core groups failed with coronal core damage (photoelastic data however, was possible to obtain at this loading condition), whereas no core damage was observed for the Ti-Core groups. Minimal stresses were observed for all post/core combinations in the unloaded state. The specimens prepared with the split-shank multi-tiered, Flexi-Post clearly distributed stress symmetrically and coronally in the loaded oblique state, while the specimens with the single tiered Para-Post showed asymmetrical apically and coronally stress patterns. Post/core combinations with Ti-Core composite were more stable than post/core combinations with GC Miracle Mix glass ionomer. The symmetric, even stresses for the Flexi-Post/core systems are more favorable than the asymmetric, uneven stresses for the Para-Post/core systems. Post/core combinations with Ti-Core a titanium reinforced composite are more stable and favorable than post/core combinations with GC Miracle Mix glass ionomer. Musikant BL, Cohen BI, Volovich Y, Deutsch AS. Flexural Strength of Six Reinforced Restorative Materials. J Dent Res 2002;81(Abstract 3841):A-470. Flexural strength (Kf) values are a key property that can be used by the dentist to predict a material’s clinical behavior under in vitro loading conditions. However, flexural strength values are obtained using a three-point bending test method, and this test method is complicated and requires extensive calculations and specialized jig apparatus to determine its value. The purpose of this study was to;1) calculate the flexural strength for six reinforced restorative materials and 2) demonstrate that flexural strength values for a dental restorative material can be determined simply by using physical parameters (such as, diametral tensile strength and Young’s modulus values) that are easily determine experimentally. Six groups were investigated in study; group 1 Ti-Core with titanium (Essential Dental Systems, Inc); group 2 Ti-Core Natural (Essential Dental Systems, Inc); group 3 Flexi-Flow with titanium composite resin cement (Essential Dental Systems, Inc); group 4 Flexi-Flow Natural (Essential Dental Systems, Inc); group 5 Ketac-Silver glass ionomer (ESPE); and group 6 GC Miracle Mix glass ionomer (GC Corporation). Groups 1 to 4 comprised composite resin restoratives reinforced with titanium or lanthanide (based on Bis-GMA polymer chemistry), where groups 5 and 6 were restoratives based on silver reinforced glass ionomer chemistry. Flexural strength values (Kf) were calculated for each of the groups using the formulas for Griffith’s equation and fracture energy (Gc) which relate flexural strength to diametral tensile strength (Dt) and Young’s modulus of elasticity (E) for a given material. Flexural strength values (Kf) were (MPa); Ti-Core with titanium 63.8 +6.5, Ti-Core Natural 62.3 +5.6, Flexi-Flow with titanium 60.3 +4.0, Flexi-Flow Natural 61.7 +5.5, Ketac-Silver 22.2 +3.9 and GC Miracle Mix 17.2 +5.5. One-way analysis of


variance (ANOVA) test and the Student-Newman-Keuls (SNK) test were performed (a statistically significant result occurred when P < 0.05) and there was a statistically significant difference among groups studied (P < 0.0001). The SNK test showed that groups 1 to 4 did not differ from one another, but were significantly larger than for each of the Ketac-Silver (group 5) and GC Miracle Mix (group 6) materials. Ketac-Silver and GC Miracle Mix glass ionomers did not differ from each other. Flexural strength values for this study were similar to those obtained for Ti-Core and Ketac-Silver determined in literature using different flexural strength test methods. Formulations based on composite resin chemistry (Ti-Core and Flexi-Flow) were superior in flexural strength compared to the glass ionomer restoratives (Ketac-Silver and GC Miracle Mix). Touati B, Quintas AF. Aesthetic and Adhesive Cementation for Contemporary Porcelain Crowns. Pract Proced Aesthet Dent 2001;13(8):611-620. This independent clinician demonstrates the Flexi-Flow Natural composite resin, fluoride releasing cement as his ideal cement based on aesthetics and retention. Cohen BI. Core Buildups and Restorative Considerations. Endodontic Therapy 2001;1(1):25. This article reviews the restorative process after the endodontic phase of treatment. The use of a bonding agent and specific post head designs, such as Flexi-Post and Flexi-Flange, have demonstrated maximum core material retention. The Flexi-Post/Flexi-Flange post systems also result in maximum retention in the root with excellent fatigue characteristics. Contemporary composite core materials, such as Ti-Core and Ti-Core Natural, which provide long-term fluoride release and exhibit strong dentinal characteristics are preferable for a successful restoration. Cimma R, Farina GA, Damiano F. Ricostruzioni Preprotesiche Con Perni Endocanalari Cilindrici: Seianni Di Esperienza Clinica. Doctor OS 2001;12(7):939-951. (Preprosthetic Reconstructions with Cylindrical Endodontic Post: Six Years of Clinical Experience. Published in Italian) The quantity of 500 reconstructed teeth were evaluated to determine the success rate of an endodontic restorative system. All teeth were restored using EDS’ AccessPost, a parallel sided multiple tiered post. Posts were cemented with Flexi-Flow titanium reinforced, fluoride releasing, resin composite cement and core build-ups were preformed using Ti-Core titanium reinforced, fluoride releasing, resin composite core material. 272 teeth were restored in the upper jaw and 228 in the lower jaw. In the course of this six year study, 15 failures occurred - none caused tooth loss. In fact 14 failures were due to separations of the reconstruction together with the post and in one case there was the fracture of the post. The results demonstrate the clinical validity of this restorative system.

Nissan J, Dmitry Y, Assif D. The use of reinforced composite resin cement as compensation for reduced post length. J Prosthet Dent 2001;86(3):304-308. Cements that yield high retentive values are believed to allow use of shorter posts. This study investigated the use of reinforced composite resin cement as compensation for reduced dowel length. The retention values of stainless steel posts (parallel-sided ParaPost and tapered Dentatus in 5-, 8-, and 10-mm lengths) luted with Flexi-Flow titanium-reinforced composite resin and zinc phosphate cements were evaluated. Single-rooted extracted human teeth with crowns (n = 120), removed at the cementoenamel junction, were randomly divided into 4 groups of 30 samples each. Different post lengths were luted with either Flexi-Flow or zinc phosphate. Each sample was placed into a specialized jig and on a tensile testing machine with a crosshead speed of 2 mm/min, applied until failure. The effect of different posts and cements on the force required to dislodge the dowels was evaluated with multiple analyses of variance (ANOVA). One-way ANOVA with Scheffé contrast was applied to determine the effect of different post lengths on the retentive failure of posts luted with the 2 agents. Flexi-Flow reinforced composite resin cement significantly increased retention of ParaPost and Dentatus dowels (P<.001) compared with zinc phosphate. One-way ANOVA revealed no statistically significant difference (P>.05) between mean retention of both dowels luted with Flexi-Flow for all posts length used (5 mm = 8 mm = 10 mm). Mean retention values of the groups luted with zinc phosphate showed a statistically significant difference (P<.001) for the different post lengths (10 > 8 > 5 mm). Parallel-sided ParaPost dowels demonstrated a higher mean retention than tapered Dentatus dowels (P<.001). In this study, Flexi-Flow reinforced composite resin cement compensated for the reduced length of shorter parallel-sided ParaPost and tapered Dentatus dowels. Penugonda B, Cohen BI. Mercury vapor analysis for a high-copper amalgam at different pH levels. Indian Dent Assoc 2002;18:23-25. The main purpose of this study was to evaluate the mercury vapor release for Tytin dental amalgam when placed in three different pH media (pH 4, 7 and 10) for two months. The use of dental amalgam as a direct restorative material has been a subject of controversy for the last two decades. Concerns have been growing over dental amalgams use and its potential safety due to leakage of elements such as mercury, copper, tin and silver. Mercury compounds and elemental mercury vapor can be neurotoxic and immunotoxic when it reaches higher levels in human body. Three capsules of Tytin amalgam were triturated (one for each pH solution) and stored in a polypropylene tube with 10 mL of a pH buffer for sixty days at room temperature. Mercury vapor analysis were performed for 60 days using a Jerome 431-X vapor analyzer. The cumulative


mercury vapor release was the highest for pH 4 (2027 µg/m3 ) followed by pH 10 (1939 µg/m3 ) and pH 7 (1250 µg/m3 ). pH 10 had a burst effect where more mercury vapor was released sooner in the first week than for pH 7 and pH 4. This effect did not last for pH 10 and after the second week the quantity of mercury vapor release was dramatically reduced. There was a significant amount of mercury vapor release in three different pH media from the Tytin Amalgam over a sixty day period. Cohen BI, Musikant BL, Deutsch AS. Ten year fluoride release from four reinforced composite resins. Oral Health 2002;92(9):44-52. Fluoride release (F-) is a desirable attribute for a material used for dental applications. In general, dental materials that release greater amounts of fluoride have greater caries prevention potential and are desirable, so long as physical and mechanical properties of the dental material are not adversely affected. Two high viscosity and two low viscosity fluoridated, reinforced resin composites were studied; Ti-Core with titanium (group 1) and Ti-Core Natural (group 2) are core build-up materials and Flexi-Flow with titanium (group 3) and Flexi-Flow Natural (group 4) are post cements. This in vitro study recorded the fluoride release for four fluoridated resin composites in deionized water measured in parts per million (ppm) over a 10 year period. Fluoride concentration was measured (in ppm) with an Accumet 925 microprocessor meter and a solid-state fluoride ion-sensitive electrode. Patterns of fluoride release were analyzed using repeated measures analysis of variance (RMANOVA) applied to the cumulative measurements over time. All results were considered statistically significant if P < 0.05. RMANOVA for periodic cumulative fluoride release levels showed a significant statistical interaction between group and week (P < 0.0001). Further analysis showed that the patterns for Flexi-Flow and Flexi-Flow Natural were not different from each other and that they were different from Ti-Core and Ti-Core Natural (which were different from one another). Essentially, the release levels for Flexi-Flow and Flexi-Flow Natural were relatively constant over time. Cumulative levels for Ti-Core and Ti-Core Natural exhibited a sharp increase until about two years, at which time the levels continued to increase, but at a slower rate. The fluoride release for these four composite resin systems (groups 1-4) appear to be similar to other reported fluoride release studies found in literature. Möllersten L, Lockowandt P, Lindén L. A comparison of strengths of five core and post-and-core systems. Quintessence International 2002;33(2):140-149. In this in vitro study, the strength of several core and post-and-core systems was compared. A second aim was to compare the strength of posts and cores on root-filled teeth with that of cores on vital teeth. The failure modes of the core and post-and-core systems were also studied. For root-filled teeth, Composipost carbon fiber

dowels and gold alloy posts and cores were tested. For vital teeth, glass-ionomer cement with threaded parapulpal retention pins, resin composite with threaded parapulpal retention pins, and gold alloy with parallel parapulpal pins ere tested. Specimens were tested in a Zwick universal material-testing machine. A significant variation in strength was found among core systems of cast gold, resin composite, and glass-ionomer cement constructed on vital teeth. The low strength values obtained for glass-ionomer cement in combination with threaded retention pins makes this combination a poor choice for core buildup. The authors investigation supports the findings of previously published studies by Dr. Cohen BI et al that glass-ionomer cores have strength values that are significantly inferior to those of resin composite cores. The Ratings � � � � Reality Publishing Co. 2002:16:146. Ti-Core resin composite core build-up material is described as easy to mix, flows well but resists slumping, and flows through needletube with ease. Ti-Core receives a four star rating. Clinical Research Associates. Core Buildup and Adhesive Incompatibility. CRA Newsletter 2000;24(6):1. Due to clinicians reporting a lack of retention of some core buildup resins to some adhesives CRA conducted the following shear bond strength test. Two dual and five auto cure core buildup materials were tested with 22 light cure and 2 auto cure adhesive bonding agents. Only 5 of the 24 adhesives bonded well to all 7 core buildup materials. They were Optibond FL, All-bond 2, Amalgambond Plus, Clearfil SE Bond, and Clearfil Liner Bond 2V. Ti-Core Natural with All-bond 2 provided the highest shear bond strength (27.0 MPa) of all composite core materials studied. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retencja materialu odbudowujacego zrab koronowy zastosowanego z trzema róznymi wkladami koronowo-korzeniowymi. Stomatologia Wspólczesna 2001;8(6):57-61. (Published in Poland: Retention of a core material supported by three post head designs) The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The


post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS’ AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Bolhuis H, DeGee AJ, Feilzer AJ, Davidson CL. Fracture strength of different core build-up designs. Ameri J Dent 2001;14(5):286-290. The purpose of this study was to investigate the resistance to fracture of three crown and core combinations, made with different core build-up systems on human teeth. Using a standardized method. The anatomic crowns were removed from three groups (n=8) of endodontically treated, human premolars in conformity with a brass master dye, using the Celay duplication device. Three of these groups were provided with a core build-up without and endodontic post (Ti-Core, Photo-Core and Ketac-Molar) and one group was not provided with a core. All groups were then prepared in conformity with a master dye. This preparation ended in axial dentin, 2mm apical from the core build-up. Thus in the grouping of premolars without a core build-up, this preparation only affected the 2mm axial dentin (ferrule), which resulted in a small retention area (2mm axial dentine) for the crown. Finally, a standard crown was cemented and 24 hrs afterwards loaded until fracture in an Instrom testing machine at an angle of 45°. Within the standardized small sampling no significant difference in core strength was demonstrated.

Restoring a tooth with little or no coronal dentin using the Flexi-Flange post system. Dent Products Report 2002;36(6):50. This article outlines a clinical procedure in which the step-by-step utilization of the Flexi-Flange post system and Ti-Core Natural, fluoride releasing, composite core material was used to produce an aesthetic restoration in a clinical case with no coronal dentin. Nissan J, Dmitry Y, Assif D. Flexi-Flow luting may allow use of shorter posts. Dental Abstracts 2002;47(3):106-107. In endodontic treatment, cements with high retentive values permit the use of shorter posts. The ability of reinforced composite resin cement to compensate for reduced dowel length was evaluated in an in vitro study. A total of 120 single-rooted human teeth with crowns were randomly assigned to receive posts of differing length and luted with different cements. The specimens were then tested to failure, and the force necessary to dislodge the dowels was compared for the different types of posts and cements. With both types of posts, retention was significantly greater with Flexi-Flow than with zinc phosphate. In specimens luted with Flexi-Flow, mean retention was similar across both post types and all 3 post lengths. In contrast, specimens luted with zinc phosphate, retention fell as the post length decreased. It was therefore concluded, the use of Flexi-Flow titanium reinforced composite resin cement allows the use of shorter posts. Blaes J. Pearls For Your Practice (Pearl 3-Flexi-Flow). Dental Economics 2002;92(3):128-129. One of the biggest requirements for a successful prefabricated post system has always been retention. Flexi-Flow Cem®, a titanium-reinforced cement was designed to enhance the retention of all prefabricated post systems. Simply mix equal amounts from the syringes for about 30 seconds, then coat the post and place cement in the canal with a spiral. Seat the post and leave undisturbed for four minutes. Flexi-Flow is a composite cement with a low viscosity that makes cementing posts fast and easy. This product comes in a natural tooth shade (Flexi-Flow Natural®) or a gray shade (Flexi-Flow Cem®). Cohen BI, Musikant BL, Deutsch AS, and Cofrancesco G. No Bisphenol A leakage from four reinforced composite resins-A Pilot Study. Oral Health 2002;92(11):22-24. Bisphenol A (BPA) is widely used in the manufacture of commercial dental products. There is limited information in the dental literature regarding estrogenic BPA released from dental materials such as composite resins and sealants. BPA (the backbone to modern composite resin chemistry) is a precursor to the composite monomer resin BIS-GMA and to bisphenol A dimethacrylate. This in vitro study was separated into four groups; Group 1, Ti-Core, Group 2, Ti-Core Natural, Group 3, Flexi-Flow and Group 4, Flexi-Flow Natural (all Bis-GMA based composites).


The quantity of 12 sample test articles (three for each group) were fabricated from stainless steel molds with dimensions of 16 mm and 2.5 mm with a weight of approximately 1 gram. Each of the 12 test articles were placed in its separate 100 mL USP Saline solution at 37 degrees celsius for a time period of 60 days. After 60 days, each extract saline solution was analyzed by Gas Chromatography/ Mass Spectrometry (GC/MS) for Bisphenol A leaching where the lowest detectable limit for measuring Bisphenol A (BPA) was 100 ppm (parts per million). All 12 test article extracts (groups 1-4) were analyzed by Gas Chromatography/ Mass Spectrometry (GC/MS) and were found to have no BPA. The only potential source of BPA for the composite resins evaluated in this study could be from the parent monomer (Bis-GMA) as a trace impurity and the results from literature and this study suggest that such impurities of BPA in parent monomers are undetectable. Duke ES. Materials Review: Reinforced Core Build-Up Materials. Compendium 2002;23(4):328-332. A comprehensive literature review of reinforced core build-up materials demonstrates the superior physical properties and clinical performance of the Ti-Core composite core build-up material. Ti-Core is reinforced with titanium and releases fluoride. Cohen BI, Penugonda B, Singh CJ, Isidro MA. Fractural Strength of Post and Core/Crown Combinations-An In Vitro Study. Oral Health 2002;92(10):49-58. The purpose of this in vitro study was to compare the effects of two post designs (Flexi-Post and Vlock) in combination with two restorative core materials (silver amalgam (Tytin) and a titanium reinforced composite resin (Ti-Core)) with a metal crown. In vitro fracture loading testing has been a common method of testing a post-core combination. However, there have been limited studies investigating the effects of a crown on the fracture strength of a prefabricated post and core. This in vitro study consisted of the preparation of 32 tooth/post and core/crown specimens. The specimens were divided into 4 groups and separated according to post and core material used. Metal cast crowns Midas gold (Au)-palladium (Pd) alloy were fabricated for each tooth/post and core combination. Each tooth/post and core/crown combination was placed in a special jig on a 45 degree angle on the buccal/lingual axis and subjected to a load on a universal testing machine (MTS Systems Corp) with a crosshead speed of 0.25 in/min (0.635 cm/min). The values for fractural strength for each group were: group 1 = Vlock/Ti-Core 140.8 + 63.6 pounds; group 2 = Flexi-Post/Ti-Core 137.0 + 59.3 pounds; group 3 = Vlock/Tytin 74.1 + 30.0 pounds; and group 4 = Flexi-Post/Tytin 138.8 + 39.7 pounds. A 2 X 2 factorial two-way analysis of variance (ANOVA) was used to test effects of core material and post type on fracture resistance. All results were considered statistically significant if p < 0.05. Group 3 had statistically lower fractural resistance than groups 1-2 and 4. Groups 1-2 and 4 were all similar to one another.

The results for this study were in the same range as other in vitro studies where post and core/crowns were tested for fractural strength. Al Wazzan, KA. Effect of Three Endodontic Materials on the Bond Strength of Two Composite Core Materials to Dentin. J Prosthodont 2002;11(2):92-97. This study investigated the effect of dentin treatment with iodine potassium iodide, calcium hydroxide or a epoxy resin sealer (AH-26) on the dentin bond strength of titanium-reinforced Bis-GMA (Ti-Core) and urethane dimethacrylate (FlouroCore) composite materials. Dentin was exposed in four groups of extracted teeth (20 specimens each). Three groups were treated with one of the contaminants and the fourth group served as the control. All specimens were stored for 1 week at 37°C and 100% humidity. The dentin surfaces were cleaned with pumice slurry using a prophylaxis rubber cup, rinsed and dried. Then the dentin surfaces were treated using the conditioner and the primer of the GLUMA adhesive system followed by placement of composite core materials. After 20 minutes debonding of the core materials was accomplished using a shear-peel test. A two-way analysis of variance and Tukey’s multiple range test was performed based upon core type and contaminant type. Pretreatment of the dentin had no effect on the bond strength of the two composite core materials. Ti-Core, titanium-reinforced (Bis-GMA) composite showed significantly greater bond strength values to dentin than the FlouroCore, (urethane dimethacrylate) composite material regardless of the dentin contaminant used. Bolhuis HPB, Pallav P, Feilzer J, DeGee AJ, Davidson CL. The Influence of Fatiguing on the Resistance to Fracture of Endodontically Treated Premolars, Restored with a Core and Crown. J Dent Res 2002;81(Spec Iss B)Abstract No. 9:B-233. Most studies into the fracture resistance of endodontically treated teeth, restored with a post, core and crown are performed without evaluation the role of fatiguing. Moreover, these studies show a wide standard error due to the variation in the shape of the teeth, core and crown. The aim of this study was to evaluate the influence of fatiguing on the resistance to fracture of endodontically treated premolars that were restored with a core, with or without a post, and a crown made according to a standardized procedure. A standard cylindrical master, with the shape of an endodontically treated decapitated human premolar was made in brass. This master was used to made a standard preparation in a human premolar using the Celay copy-milling machine. The prepared premolars were provided with a core. Four groups (n=16) were prepared with different materials: the resin-based composites Ti-Core (EDS, USA), and Photo-core (Kuralay, Japan), the traditional glass-ionomer Ketac-Molar (Espe, Germany), all without post, and Duralay (Dental Mfg, USA) and a Tenax burnout post (Coltene Whaledent, USA) to made a conventional gold cast


core. In the fifth Group, the premolars were not built up with a core material. After this part of restoration, the teeth of all Groups were prepared again by using a second master with the shape of a standard crown preparation. This preparation was ending in 2 mm sound dentin (Ferrule), so in the fifth group this preparation affected only the axal dentin. Cast crowns with a standard shape were cemented with Ketac-Cem (Espe, Germany) on the prepared teeth. At least after 24 hours, the crowns were loaded under a 45º angle until fracture. 50% of each Group (n=8) was previously exposed to occlusal fatigue loading (106 X 57 N under a 45º angle). During this procedure the samples were in 37º water. For all Groups, fatiguing led up to a significant (p>0.05) reduction in fracture resistance. This reduction was their lowest for cores of Ketac-Molar. Before and after fatiguing, no significant differences in fracture resistance between the different core material were found (even by absence of a core). As the latter may be attributed to the loading angle of 45º, a loading and fracturing procedure under a 90º angle might be insistent. Ti-Core resin-based composite had statistically better fatigue characteristics then for the Ketac-Molar (traditional glass-ionomer) specimens. Akisli I. Ozcan M, Nergiz I. Resistance of core materials against torsional forces on differently conditioned titanium posts. J Prosthet Dent 2002;88(4):367-374. This study evaluated the resistance to torsional forces of various core materials adapted to differently conditioned titanium posts. Seven hundred and twenty (720) specimens were tested consisting of; 6 core materials and 5 surface conditioning techniques for 2 kinds of opaquers with 10 specimens in each group plus 6 core materials and 2 opaquers were tested and considered as control groups on nonconditioned titanium posts, each group containing 10 specimens. The custom-made pure titanium posts were conditioned with the 2 kinds of opaquers and subsequently, 6 core materials with different compositions (Durafill, Adaptic, Coradent, Ti-Core, Hytac, and Photoac-Fil). Sixty air-abraded titanium posts were used as a control for each core material. Following thermocycling (5° to 55°C, 30 seconds, 5000 cycles), maximum torsional forces ere determined with an electronic torque movement key. Data was statistically analyzed by a 1-way analysis of variance followed by 2-way analysis of variance. (P<.05). Results showed microfilled composite and resin-modified glass ionomer core materials offered poor resistance to torsional forces. Composite core materials (such as Ti-Core) were recommended for use with titanium posts. Musikant BL, Cohen BI, Deutsch AS. In Vitro Abrasive Wear Resistance for Five Core Build-up Materials. J Dent Res 82 (Spec Iss A):1667, 2003. The ability to resist mechanical wear (abrasion) is an important requirement of a dental composite

restorative material. There are limited studies in the literature detailing composite core build-up abrasion. The purpose of this in vitro study was to conduct wear abrasion for five composite core build-up materials ( Ti-Core, Ti-Core Natural, Luxacore Automix (Dual), Build-It FR, and Core Paste Syringeable) using a wear testing apparatus with a silicone carbide counterface (Dura-Green Stones), measuring the loss of height or the depth of wear for each restorative material. Abrasive wear testing was performed with a testing apparatus incorporating a Healthco Dental Engine set at a speed of 1000 rpm’s. After abrasive wear testing was completed all depth of wear (loss of height) measurements were performed using an electronic caliper. The percentage decrease of depth of wear ranged from a low of 0.66% (Ti-Core) to a high of 11.38% (Build-it FR). Group/ Core Material Control (mm) Depth of wear (mm) % Decrease of Active treatment Depth of Wear 1- Ti-Core 2.575 + 0.027 2.558 + 0.015 0.66 % 2- Ti-Core Natural 2.583 + 0.023 2.539 + 0.022 1.70 % 3- Luxacore Automix 2.756 + 0.040 2.445 + 0.078 11.28 % 4- Build-it FR 2.918 + 0.057 2.586 + 0.098 11.38 % 5- Core Paste 2.639 + 0.020 2.457 + 0.042 6.89 % Note: The lowest percent decrease of depth of wear represents the best wear resistance. Two-way analysis of variance (ANOVA) with interaction term was used to compare mean abrasive wear resistance between treatment conditions and between composite materials and showed a significant interaction between materials and treatment (P < 0.0001). The mean for active treatment was significantly less than the control for Build-it, Luxacore and Core Paste. Active treatment and control did not differ for Ti-Core and Ti-Core Natural. Therefore, Both Ti-Core and Ti-Core Natural had the highest wear resistance and demonstrated statistically better wear than all the groups studied. Tezvergil A, Lassila LVJ, Vallittu PK. Effects of Adhesion on the Composite-Composite Bond Strength. J Dent Res 82 (Special Issue B (Goteborg Abstracts)):Abstract #1809,2003. Repairing an old composite restoration can be alternative for replacing the restoration. The composite-composite bond can be achieved via polymer matrix, or to the exposed filler particles. Recently new products have been introduced. They contain resin monomers that are used as "one-step" primers or monomers and silane coupling agents which are used separately ("multi-step"). Objectives: To determine the shear bond strength of the new composite resin to aged composite, by using different adhesion primers compared to intermediate resin. Methods: The substrates were particulate filler composite (Z250, 3M-ESPE), which were aged by boiling 8 hours and storing at 37C water for 3 weeks. The aged substrate surfaces were wet ground flat with 320-grit SiC-paper and subjected randomly (n=8) to one-step adhesion primer: Compoconnect (CC) (Heraus Kulzer) or multi-step: Clearfil Repair (CF)


(Kuraray) according to manufacturers recommendations. Scotchbond Multipurpose adhesive resin was used as intermediate resin control (MP) (3M-ESPE). New composite resin (Z250) was added on the substrate using 2 mm layer increments and light cured (Optilux-501, Kerr). The specimens were either water stored for 24 hours or thermocycled for 6.000 cycles. The shear bond strengths were measured with a crosshead speed of 1mm/min at a universal testing machine. Data was analyzed by two-way ANOVA and Turkey’s post-hoc tests (p=0.05) Results: ANOVA revealed significant differences between the primers (p<0.05). CF showed higher bond strength than CC and control (p<0.05). CC and MP did not show significant difference (p>0.05). Storage condition did not show significant difference (p>0.05) on bond strength values. The mean bond strengths were Mpa (SD): CC CF MP (Control) Water storage 31.7(6.3) 44.6 (5.7) 35.7 (8.4) Thermocycled 28.0 (6.1) 42.4 (8.8) 33.4 (7.2) Conclusion: It was concluded that multi-step adhesion primer yielded higher bond strength compared to one-step primer or intermediate resin. Schmage P, Nergiz I, Czajkowska A, Platzer U. Retentive Strength of Root Posts Influenced by Endodontics Treatment. J Dent Res 82 (Special Issue B (Goteborg Abstracts)):Abstract #0327,2003. Objectives: The root post preparation is performed after the root canal filling of the tooth. This previous treatment may influence the retentive strength of the post. The aim of this study was to evaluate the retentive strength of posts fixed with four different bonding agents in teeth with and without previously filled root canals. Methods: 60 extracted, anterior teeth underwent an individual endodontic treatment using a master file of ISO size 60 and were filled using the lateral condensation technique. 60 teeth served as control. The root canals of all teeth were prepared for sand blasted Titanium Erlangen posts (size II, corresponding to ISO size 90, length 12mm). The posts were fixed in the root canals (n=15) using three composites and a zincphosphate cement (Compolute, ESPE, Seefeld, Germany; Flexi-Flow, EDS, NJ, USA; Panavia 21 EX, Kuraray, Osaka, Japan; Tenet, Vivadent, Schaan, FL). A tensile force test (Instron 1026, Mass., USA) was performed after moist storage for 24 hours and thermocycling (5-55C, 500 times). The results were statistically analyzed (ANOVA-test, Scheffe-correction). Results: The retentive strengths of the four control groups ranged between 352N ± 35N for Compolute and 455N ± 110N for Flexi-Flow, but did not differ significantly from each other. The results decreased significantly in all endodontically treated groups (p<0.05). In this case, the retentive strength values were 207N ± 38N for Compolute, 223N ± 25N for Panavia, 280N ± 20N for Tenet and 314N ± 31N for Flexi-Flow. A

significant difference was found between Compolute and Flexi-Flow (p<0.05). Conclusion: Using root posts, it should be taken into account that the previous root canal treatment could cause a reduction of the retentive strength. All tested cements and composites with either mechanical or chemical bonding mechanisms were affected. Flexi-Flow gave the highest retentive strength of all groups studied. Angerame D. Biasotto M, Di Lenarda R, Visintini E. Adhesion to Dentin of a Self-curing Composite Resin by using a Light-curing Adhesive System. J Dent Res 82 (Special Issue B (Goteborg Abstracts)):Abstract #1813,2003. Objective: The combined use of self curing composite resin and light curing adhesive system is not sufficiently studied; that combination of materials can be useful in some clinical procedures. The aim of the present work was to evaluate in vitro the adhesion of a self curing composite resin bonded to dentin by a light curing adhesive system. Methods: A total of 24 dentin specimens were obtained by the cross-section of human molar and premolar crowns maintained in a saline solution beneath the occlusal surface and upper to the pulpal chamber: the dentin surfaces were acid etched (25 sec) (Total Etch, Vivadent, Italy). The specimens were randomly assigned to two groups: in the study group (G1) the Scotchbond Multipurpose Plus adhesive system was applied to them and light cured (30 sec;Optilux 501, Demetron Research Corp., Danbury, Conn., USA); in the control group (G2) it was self cured. A Teflon mold (internal diameter 2,6 mm) was filled with a self curing composite resin (Ti-Core Natural, EDS, USA) and then positioned onto each dentin surface; after the composite was cured the Teflon mold was gently removed. All the specimens so prepared were aged (200 5 to 55° C thermal cycles) and stored in a saline physiological solution during the sperimentation; after 10 days they underwent to shear bond test. The data were statistically analyzed (Student t test, SPSS 11.0 Statistical Package). Results: The ultimate shear strength average was 10, 78 (DS 5,59) in G1 e 12,-2 (DS 3,99) in G2; there was no statistical difference. Conclusions: Under the condition of this sperimentation, the adhesion to dentin of the self curing composite resin is not strongly affected from the polymerization mechanism of the adhesive system. Cohen BI, Musikant BL, Deutsch AS. Fluoride Release from Four Reinforced Composite Resins: A 10 Year Study. J Dent Res 82 (Special Issue B (Goteborg Abstracts)):Abstract #2001,2003. Fluoride release (F-) is a desirable attribute for a material used for dental applications. Objective: Two core materials and two post cements were studied; Ti-Core with titanium (Essential Dental Systems S. Hackensack, NJ) (group 1) and Ti-Core Natural (EDS) (group 2) and Flexi-Flow with titanium (EDS) (group 3) and Flexi-Flow Natural (EDS) (group 4). Methods:


This in vitro study recorded the fluoride release for four fluoridated resin composites in deionized water measured in parts per million (ppm) over a 10 year period using an Accumet 925 microprocessor fluoride meter and a fluoride electrode. After time intervals of approximately (days/years): one day, 7, 14, 21, 30, 45, 60, 90, 180, 365 (one year), 1.5 years, 2, 2.5, 3, 3.5, 4, 4.5, 5 years, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, and 10 years measurements were taken. Patterns of fluoride release were analyzed using repeated measures analysis of variance (RMANOVA) applied to the cumulative measurements over time. All results were considered statistically significant if P < 0.05. Results: RMANOVA for periodic cumulative fluoride release levels showed a significant statistical interaction between group and time (P < 0.0001). Both Flexi-Flow and Flexi-Flow Natural were not different from each other and they were different from Ti-Core and Ti-Core Natural (which were different from one another). Essentially, the release levels for Flexi-Flow and Flexi-Flow Natural were relatively constant over time. Cumulative levels for Ti-Core and Ti-Core Natural exhibited a sharp increase until about two years, at which time the levels continued to increase, but at a slower rate. Conclusions: The fluoride release for these four composite resin systems appear to be similar to other reported fluoride release studies found in literature and cumulative 10 year fluoride release values were (Groups 1-4): 51.64 ppm, 44.98 ppm, 5.29 ppm and 6.13 ppm. Bapanaiah Penugonda, Brett I. Cohen, and Chandan J. Singh. Fractural Strength for Post and Core/Crown Combinations. J Dent Res 82 (Special Issue B (Goteborg Abstracts)):Abstract #2671,2003. Objective: This in vitro study was to test and compare the effects of two post designs (Flexi-Post and Vlock) in combination with two restorative core materials (silver amalgam (Tytin) and a titanium reinforced composite resin (Ti-Core)) with a metal crown. In vitro fracture loading testing has been a common method of testing a post-core combination. However, there have been limited studies investigating the effects of a crown on the fracture strength of a prefabricated post and core. Methods: This in vitro study consisted of the preparation of 32 tooth/post and core/crown specimens. The specimens were divided into 4 groups and separated according to post and core material used. Metal cast crowns Midas gold (Au)-palladium (Pd) alloy were fabricated for each tooth/post and core combination. Each tooth/post and core/crown combination was placed in a special jig on a 45 degree angle on the buccal/lingual axis and subjected to a load on a universal testing machine (MTS Systems Corp) with a crosshead speed of 0.25 in/min (0.635 cm/min). Results: The values for fractural strength for each group were: group 1 = Vlock/Ti-Core 140.8 ± 63.6

pounds; group 2 = Flexi-Post/Ti-Core 137.0 ± 59.3 pounds; group 3 = Vlock/Tytin 74.1 ± 30.0 pounds; and group 4 = Flexi-Post/Tytin 138.8 ± 39.7 pounds. A 2 X 2 factorial two-way analysis of variance (ANOVA) was used to test effects of core material and post type on fracture resistance. All results were considered statistically significant if p < 0.05. Group 3 had statistically lower fractural resistance than groups 1-2 and 4. Groups 1-2 and 4 were all similar to one another. Conclusions: The results for this study were in the same range as other in vitro studies where post and core/crowns were tested for fractural strength. Sen D, Akgungor G. Shear Bond Strengths of Two Composite Core Materials After Using All-in-One and Single-bottle Dentin Adhesives. J Prosthodontics Dent 2005; 14(2):97-103 The purpose of this study was to compare the shear bond strengths of 2 composite core materials after using all-in-one and single-bottle dentin bonding materials. The occlusal surfaces of 100 extracted, intact human third molars were ground to expose a flattened area of dentin and polished with 600-grit silicone carbide paper. Specimens were divided into 5 main groups (n=20). Three all-in-one (AQ Bond, One-Up Bond, Xeno-CF Bond) and 2 single-bottle adhesives (Single Bond, One-Step Plus) were used. Each group was further divided into 2 subgroups. Ti-Core and Built-it F.R. core materials were applied using a translucent plastic ring (diameter: 3 mm, height: 5 mm). After storage in 37 degree Celcius water for 24 hours, shear bond strengths were measured using a Universal testing machine with a crosshead speed of 0.5 mm/min. Debonded dentin surfaces were examined with SEM. Two-way analysis of variance (ANOVA) and multiple comparison (Tukey) tests were used for statistical analysis of data. Results: Two-way ANOVA revealed that the type of core material did nto significantly influence the shear bond strength (p. 0.0001). Shear bond strengthst for single-bottle adhesive systems were significantly higher than those for all-in-one adhesive systems (p, 0.05). The fracture modes were predominantly adhesive for all-in-one adhesives and cohesive for single-bottle adhesives. Conclusion: Bonding of composite core materials with the newly developed all-in-one dentin adhesives produced lower shear bond strengths as compare with single-bottle adhesives. Smarge P, Sohn J, Ozcan M, Negriz I. Effect of surface treatment of titanium posts on the tensile bond strength. Dental Materials 2006;22:189-194. The purpose of this investigation was to investigate the effect of two conditioning treatments on the tensile bond strength of four resin-based luting cements and zinc phosphate cement to titanium posts. The composite resin luting cements did not show significant differences (P<0.05)showing values between (352±76 n-475±104 N) when the posts were air-abraded. Afterica silica coating and silanization,


significantly higher (P<0.05) tensile strengths were obtained for Compolute® Aplicap (600±123 N) than those of the other lutic cements (Flexi-Flow cem TM:191±62 N; Panavia® 21 EX:375±77; Twinlook; 430±78 N). No significant differences (P>0.05) were found between the tensile strength of the posts luted with zinc phosphate (414±102 N) and the resin composite cements. Silica coating and silanization revealed the highest tensile bond strength in posts luted with Compolute® Aplicap but it was not effective for the other experimental groups. Zinc phosphate cement exhibited tensile bond strength as good as resin composite cements. Single-Step, Self-Etch ADhesives Behave as Permeable Membranes After Polymerization. Tay FR, Pashley DH, Suh B, Carvalho R, Miller M. Am J Dent 2004;17:271-278. The purpose of this is test the hypotheses that microtensile bond strengths of single-step, self-etch adhesives to hydrated dentin are adversely affected by delayed-activation of a light-cured composite, as well as the use of a chemical-cured composite. Results: For all adehsives, bond strengths decreased significantly to bonded hydrated dentin when the composites were activated with [2] or [3] (P<0.001). Whereas the hybrid layer-adhesive interface was intact, water-blisters that developed along the adhesive-composite interface in these two modes were responsible for the decline in bond strength. When bonded to hydrated dentin, delayed light-activation of the light-cured composite did not result in compromised bond strength. The results of chemical-cured composites improved but were more variable and system-dependent. Simplified adhesive systems decline with time. Dental Materials 2004;49:5 Background.- Simplified, 1 bottle and self-etching primer systems have been developed to minimize the

technique sensitivity and allergic potential of multiple-step adhesive systems. The durability of 3 simplified systems was compared. Results.- Only 3 restorations were not evaluated at all recall points. No patients had sensitivity postoperatively. Twenty-one restorations (14.6%) were lost during follow-up. Loss occurred in 8.7% of those that used 2 –step system, 13.0% of those that used the all-in –one system, and 21.2% of those that used the 1-bottle system at the 24-. Dental Advisor Plus. July/August 2005;Vol. 22:No 6 Flexi-Fow Auto/Flexi-Flow Auto E +++1/2 (Essential Dental Systems, Inc., 89 Leuning Street, South Hackensack, NJ 07606 Description Flexi-Flow Auto and Flexi-Flow Auto E are self-curing resin cements indicated for use with prefavricated psots systems. The cement is supplied in a dual-barrel syringes with mixing and long, thin delivery tips. Flexi-Flow Auto is titanium-reinforced and available in a gray shade. Flexi-Flow Auto E esthetic cement is lanthanide-reinforced and available in shade A2. Both cements are radiopaque and contain fluoride. Neither of these Flexi-Flow cements should be used with self-cured bonding agents. Working time is three minutes, and setting time is five minutes after the start of mixing. Each kit contains two syringes with 4.5 g each of base and catalyst, 20 mixing tips and 20 delivery tips. Thirty consultants used and evaluated Flexi-Flow Auto and Flexi-Flow Auto E in over 200 post cementation procedures. This product received a 94% clinical rating.

Gu S, Isidro M, Deutsch AS, Musikant BL. Comparison of the Retention of 5 Core Materials Supported by a Dental Post. Int J Prosthodont 2006;19:151-152. This study evaluated the retention fo dental post heads (No. 2 Flexi-Post) embedded in five core materials (one automix resin composite, two hand-mixed resin composites, and two glass ionomers). Materials and Methods: Samples were prepared by embedding post heads in 4.5-mm-thick discs of core material. Results: The resin composite materials provided significantly more retention that the glass-ionomer-based materials. The post head retention of the auto mix resin composite was comparable to that of the hand mixed resin composites. Conclusion: Unlike the resin composite samples, all the glass- ionomer samples fractured during testing. This is an unacceptable condition for a clinically successful restoration.

Thesis by: Salah Abdel – Azeem Youseif Nasr Effect of ferrule length on fracture resistance of teeth restored with two different posts cemented with two types of luting materials. Within the limitation of this in vitro study the following conclusions may be drawn:

1.The fracture resistance of endodentically treated teeth increased with increasing the coronal dentinal structure (Ferrule length). 2. The fracture resistance of endodentically treated teeth restored by flexi post cemented

with composite resin was higher than others cemented with zinc phosphate.

The fracture resistance of endodentically treated teeth restored with cast post and cemented with composite resin was higher than cast post cemented with zinc phosphate.


3. The fracture resistance of endodentically treated restored with flexi-post and Ti core was higher than cast post and its core.

Product Features Flexi-Flow Auto and Flexi-Flow Auto E are easy to use with the auto mix feature. The delivery tips are outstanding for application of cement directly in to the post space. Viscosity of the cement is very good- not too runny or too thick – and the flow into the canals is adequate. Working time is adequate, and the cement sets very hard in a reasonable amount of time. Some consultants indicated a desire for dual-cured capabilities for control of the setting time. Excess cement is esy to remove at the gel state. Because the material does not require a bonding agent, post cementation is accomplished simply and efficiently. Generally the esthetic shade was preferred. Eighty-eight percent of the consultants rated Flexi-Flow Auto and Flexi-Flow Auto E to be equivalent to or better than the product they currently use to cement posts. Eighty-five percent would switch to Flexi-Flow Auto/Flexi-Flow Auto E and recommend the products to a colleague. Clinical Tips

• Move delivery tips slowly out of canal to minimize air bubbles.

• For maximum depth of cement placement, use a lentulo spiral to spin cement to the apical end of the post space.

• Retention may be increased by etching or placing groves in the post space.

• Do not use a bonding agent with this cement – it greatly accelerates the setting time.

- AND –

Ti-Core Auto E ++++1/2 Ti-Core Auto E is a dual-cured hybrid composite core material for vital and non-vital teeth. It is reinforced with lanthanide, contains fluoride and is radiopaque for easy identification. Any 4rh -, 5th- or 6th generation/type1 bonding agents may be used for bonding Ti-Core Auto E. It is packaged in dual-barrelled syringes containing 4.5g base and catalyst in shade A-2. The kit contains two syringes of Ti-Core Auto E, mixing tips and intra-oral tips. The working time is 3:45 minutes with a chemical cure time of six minutes. Light curing for 20 seconds is sufficient with any halogen light for a 2-mm thickness. Twenty-three consultants evaluated Ti-Core Auto E in 238 clinical applications. This product received a 91% clinical rating. Product Features The automix feature of Ti-Core Auto E with the use of the intraoral tips eliminates hand mixing and loading into a syringe tip, while allowing precise direct placement of the material, which was rated as very good optimizes adaptationof the core to the

cavity walls, posts and pins. The working time is more than adequate even for large core build-ups, and the dual-cured feature permits a command set by light curing to a maximum depth of 4mm. The preparation of the set core, minimizing gouging of the surface. Eighty-two percent of consultants rated Ti-Core Auto E equivilant to or better than the material they were currently using, while 87% would recommend it and 61% would switch to Ti-Core Auto E. Ratings Excellent +++++ Very Good ++++ Good +++ Gu S, Rasimick BJ, Deutsch AS, Musikant, BL In Vitro Evaluation of Five Core Materials J Prosthodont 2007;16:25-30 Purpose: This invitro study determined the fracture strength of five core materials supported by two different endodontic dowels. Diametral tensile strength and microhardness of three resin composite core materials used in this study were also tested. Material and Methods: The fracture strength study used one lanthanide-reinforced flowable resin composite (Ti-Core Auto E), one titanium- and lanthanide-reinforced composite (Ti-Core), one lanthanide-reinforced composite (Ti-Core Natural), and two metal-reinforced glass ionomer core materials (Ketac Silver and GC Miracle Mix). Two types of dowels were used: a multitiered, split-shank threaded dowel with a flange (#1 Flexi-Flange) and one without a flange design (#1 Flexi-Post). The specimens were divided into ten groups. Each tooth/dowel and core specimen was placed in a special jig at 45º and subjected to a load by a universal testing machine. The diametral tensile strength and the michrohardness of the three resin composite core materials were measured by a universal testing machine and Barcol hardness tester, respectively. All test groups contained ten specimens. Results: The fracture strength value of the resin composite core materials was significantly larger (p< 0.0001) than those for the metal-reinforced glass-iionomer core materials. Analysis of variance (ANOVA) also showed that the Flexi-Flange dowel interacted with Ti-Core and Ti-Core Auto E to significantly (p < 0.0013) increased the fracture strength relative to the Flexi-Post. One-way ANOVA revealed that there were no significant differences between them in terms of diametral tensile strength. The Barcol hardness values of the composite core materials were statistically different (p , 0.0001), with the Ti-Core the highest, followed by Ti-Core Natural, Then Ti-Core Auto E. Conclusions: Resin composite core material performed better than glass iionomer material in this in vitro study. The flowable composite core material


performed about the same in terms of fracture strength and diametral tensile strength compared with nonflowable composites. Combined with certain core materials, the flange design increased the fracture strength of the tooth/dowel and core combination. Rasimick BJ, Gu S, Deutsch AS, Musikant BL Measuring the Radiopacity of Luting Cements, Posts, and Core Build-up Materials with a Digital Radiography System Using a CCD Sensor J Prostodont 2007;1-8 Purpose: This study assessed the radiopacity of five luting cements, five posts, and five core build-up materials using two target distances. Material and Methods: Materials were analyzed using a modified version of ISO protocol 4049. 1-mm thick samples were digitally radiographed alongside a stepwedge fo aluminum alloy 1100 using a Trophy RVG-4 CCD sensor and 70 kVp X-ray generator. The gray-scale values of the stepwedge and sample were converted to X-ray absorbencies. The relationship between X-ray absorbance and aluminum thichness was linear for thickness and less than 10 mm and followed a power-law relationship above 10 mm. These relations were used to convert the absorbencies of the samples into aluminum thicknesses. The radiopacity data was subjected to ANOVA/Student-Newman-Keuls testing. Results: All materials were more radiopaque than equivalent thicknesses of aluminum. Each product category contained a wide range of radiopacities. Syringe-dispensed materials tend to be less radiopaque than materials dispensed by mechanically assisted syringe or mixed by hand (p < 0.01). Target distance did not affect the measured radiopacity so long as the exposure time was suitably adjusted (p = 0.86). Conclusions: All luting cements and core materials met or exceeded the ISO minimums. The tested metal-reinforced glass ionomer core build-up materials were extremely radiopaque. Some publications suggest that excessively radiopaque core materials can hinder a clinician’s ability to spot voids or marginal defects.

EDS’ ACCESSPOST™ 4/1 & EDS’ ACCESSPOST™ OVERDENTURE

EDS’ ACCESSPOST™ EDS’ AccessPost is a unique hollow tube post and patented system, designed to provide easy post removal and access to the apex, in the event of a failed root canal. With the special retreatment drills, retreatment now becomes a routine, non-surgical procedure. The second tier provides high retention, stability and even distribution of stresses under function, thus preventing the high apical stresses common to traditional passive posts. EDS’ ACCESSPOST™ OVERDENTURE The EDS AccessPost Overdenture is constructed as a ball and socket, with the (male) ball located on the coronal end of the EDS AccessPost. The (female) socket is made of nylon and is easily incorporated into the denture. WORLD POST (not available in the U.S.) Based on a unique hollow tube design, the patented World Post system is a parallel sided passive post that provides easy post removal and access to the apex. With the special retreatment drills, retreatment now becomes a routine, non-surgical procedure. Cohen BI, Condos S, Deutsch AS, Musikant BL. Cyclic fatigue of seven endodontic post systems. (Essential Dental Laboratories, S. Hackensack, NJ, USA). J Dent Res (IADR) Abstract 1993;72:305. The purpose of this pilot study was to test the comparative fatigue of seven commercial prefabricated post systems (Flexi-Post, Flexi-Flange, Vlock, ParaPost, Cytco, World Post and EDS’ AccessPost) under simulated clinical condition, with the use of an in vitro fatigue machine. The experiment was divided into seven separate groups with each group comprising five samples each. The maximum average anterior biting force of 60 pounds generated in the mouth was found to be equivalent to an instantaneous applied force of 5 pounds generated with a fatigue testing apparatus (in vitro). Data was recorded when a post broke. If the post did not break, the test was stopped 2,000,000 repetitions. ANOVA one-way analysis of variance (p<0.05) was obtained to determine which groups

differed from one another. Cyclic results were (N=5): Flexi-Post, Flexi-Flange, ParaPost, World Post and EDS’ AccessPost 2,000,000, 2,000,000, 2,000,000, 2,000,000 and 2,000,000 with an average of 2,000,000 repetitions with no failures; Cytco post 29,339, 22,982, 16,713, 34,676, 73,492 with an average of 35,440 repetitions with failures, and Vlock post 2,000,000, 76,187, 327,493, 236,022 with an average of 927,940 repetitions with failures. Flexi-Post, Flexi-Flange, ParaPost, World post and EDS’ AccessPost designs all had a statistically greater number of repetitions (with no failures) than Vlock and the Cytco post designs. No difference in the number of repetitions was found for the Vlock vs. the Cytco post system. Cohen BI, Deutsch AS, Musikant BL. Cyclic fatigue testing of six endodontic post systems. J Prosthod 1993;2:28-32. The purpose of this study was to test the comparative cyclic fatigue of six prefabricated post systems (Flexi-Post, Flexi-Flange, Vlock, ParaPost, Cytco and a hollow tube post design, EDS’ AccessPost). Cyclic fatigue testing was obtained with an in vitro fatigue machine, which simulated clinical fatigue conditions. An instantaneous applied force of 5.0 pounds was applied to each post specimen and data was recorded when post breakages occurred. If no breakage occurred, then the test was stopped after 2,000,000 repetitions. Results were as follows: Flexi-Post X=2,000,000 repetitions with no failures, Flexi-Flange X=2,000,000 repetitions with no failures, ParaPost X=2,000,000 repetitions with no failures, Hollow tube post design, EDS’ AccessPost X=2,000,000 repetitions with no failures, Cytco Post X=35,440 repetitions with failures, and Vlock post X=927,940 repetitions with failures. Failures only occurred with the Cytco and Vlock post designs. While the Flexi-Post, Flexi-Flange, ParaPost and Hollow tube post design (EDS’ AccessPost), all had greater resistance to cyclic fatigue with no failures. This experimental design may simulate biting forces and stresses seen for posts in a clinical situation. Cohen BI, Musikant BL, Deutsch AS. Comparison of the retentive properties of two hollow tube systems to a solid post design. J Prosthet Dent 1993;70:234-8. The retention of the post in the root is of key importance for a successful restoration. The purpose of this study is to compare the retention of two hollow


tube post designs (EDS’ AccessPost and World post) cemented with either zinc phosphate cement or a titanium reinforced composite cement (Flexi-Flow cem with titanium) to that of the ParaPost system (solid post design) cemented with zinc phosphate cement (ZOP) (control). The experiment was divided into 11 groups comprising ten samples each. Retention values were obtained with a universal testing machine and data obtained was recorded in pounds. Statistical analysis (one-way analysis of variance (ANOVA) was performed, including Duncan's multiple comparisons test, Tukey's studentized range test and Dunnett's test. Both Duncan's multiple comparison test and Tukey's test reveal inconclusive results. Only Dunnett's test revealed a significant difference between group 5, EDS’ AccessPost, grooved dentin with Flexi-Flow cem with titanium (mean of 89.7 pounds) and the control, group 11 ParaPost cemented with ZOP (mean of 61.3 pounds). all other groups were similar in terms of the retention, with retention values ranging from 62 to 76 pounds. Cohen BI, Pagnillo M, Condos S, Musikant BL, Deutsch AS. Post removal using a thick-walled hollow tube post design. Oral Health 1994;84:15-22. The retention of a post into the root is critical for the successful restoration of an endodontically treated tooth. A total of 80 EDS’ AccessPost (Nos. 0, 1, 2, and 3) comprising eight groups were cemented in root canals with two different luting agents, Flexi-Flow cem with titanium and zinc phosphate cement. Removal of these EDS’ AccessPosts was then performed with the corresponding retreatment drills. None of the samples for the No. 0 EDS AccessPosts were removed by extraction with the retreatment drills. None of the samples for the No. 1 EDS AccessPost cemented with zinc phosphate were removed by extraction with the retreatment drills. All these posts were removed by hand with a hemostat, after breakage of the cement seal. 60% (group 3) and 40% (group 7) of samples for the No. 2 EDS AccessPosts were removed by extraction with the corresponding retreatment drills. 80% (group 4) and 70% (group 8) of samples for the No. 3 EDS AccessPosts were removed by extraction with the corresponding retreatment drills. On an average removal of each EDS AccessPost (Nos. 0 an 1) took between 1 and 2 minutes. On an average removal of each EDS AccessPost (Nos. 2 and 3) took between 2 and 3 minutes. No root fractures were observed for any sample with either technique. This was confirmed by visual and radiographic analysis.

Deutsch AS, Cohen BI, Condos S, Musikant BL. Comparison of the retentive properties of three passive post systems. J Dent Res 1994;73 Abstract 1791:326. The retention of a post in a tooth root is critical for the successful restoration of an endodontically treated tooth. This study compared the retention of two hollow tube post designs (AccessPost (AP) and World Post (WP) cemented with either zinc phosphate (ZOP) or titanium reinforced composite resin cement (Flexi-Flow cem with titanium) to the control, ParaPost (PP) (solid post design cemented with zinc phosphate cement). In addition, the root canal for the experimental groups were either etched with 37.5% phosphoric acid or grooved with a special grooving drill. The experiment was divided into 11 groups each comprising ten samples. Retentive values were measured with a universal testing machine and the data obtained was recorded in pounds. A one-way analysis of variance (ANOVA) was obtained, including Duncan's multiple comparisons test, Tukey's studentized range test and Dunnett's test. Values for retention were (pounds): group 1-AP/ZOP (74.6 + 20.9), group 2-AP/grooved, ZOP (74.0 + 26.2), group 3-AP/etched, Flexi-Flow (76.3 + 20.6), group 4-AP/etched & grooved, Flexi-Flow (74.3 + 17.4), group 5-AP grooved, Flexi-Flow (89.7 + 10.8), group 6-WP/ZOP (59.3 + 14.7), group 7-WP/grooved, ZOP (62.2 + 16.9), group 8-WP/etched, Flexi-Flow (48.2 + 7.2), group 9-WP/etched & grooved, Flexi-Flow (70.9 + 25.7), group 10-WP/grooved Flexi-Flow (73.8 + 18.0), and group 11-PP/ZOP (61.3 + 17.9). Both Duncan's multiple comparison test and Tukey's test were inconclusive in showing significance between groups studied. Only Dunnett's test revealed a significant difference in retention between group 5 (AP/grooved dentin, Flexi-Flow) and the control, group 11 (PP/ZOP). All other groups exhibited similar results, with retention values ranging from 48 to 76 pounds. Rovatti L, Dallari A, Mason P.N. A new system of endodontic retention-the World Post. Attualita Dentale 1994;18:4-26. An in vitro and clinical experiment involving a core buildup system for devitalized teeth was studied. This system consists of an endodontic post, World Post, used with a composite cement Flexi-Flow, a core buildup material Ti-Core, and a retreatment kit with appropriate


drills for the purpose of post removal. The post shape characteristic is special, with a long head (which can be bent as desired to gain increased retention for the core material). The hollow-tube feature allows for the removal of the post without the possibility of causing damage to tooth structure (ie., without widening the root canal). In this study the World Post was subjected to tensile testing, resulting in exceptional values varying from a minimum of 94.6 kg force to a maximum of 104.5 kg of force. The World Post system offers excellent characteristics of compressive strength in vitro. This accounts for the perfect adhesion of the cement to the post and the root canal. Tests indicate that other passive parallel posts such as, Unity Post resulted in much lower retention values. Flexi-Flow, a composite cement reinforced with titanium was also studied and enables one to reach a compressive strength equal to 289 MPa and a diametral tensile strength of 36 MPa. These strengths were similar to dentin. Ti-Core is a paste composites, auto-polymerizable enriched with the incorporation of titanium. Results for Ti-Core were; a compressive strength equal to 284 MPa while the compressive strength of dentin 297 MPa. Ti-Core is compatible with any bonding or adhesive dental bonding agent. The World Post was conceptually conceived to be removed if necessary. Its usefulness may be considered remarkable, when it is necessary to reconstruct an element that is endodontically risky. The World Post performs in compressive strength and retention much better than other posts which are not hollow. The Dental Advisor Plus. January/February 1995;5:1. EDS’ AccessPost ++++ 1/2 (Essential Dental Systems, Inc. 89 Leuning S.t, S. Hackensack, NJ) TDA PLUS Recommendation EDS’ AccessPost is Highly recommended as a parallel-sided passive post for restoring nonvital teeth. It received a 92% approval rating. Description EDS’ AccessPost is a prefabricated, parallel-sided passive post with a thick-walled, hollow tube design.

The hollow tube vents hydrostatic pressure during post cementation and facilitates post removal. Post removal may be indicated for non surgical endodontics retreatment. Retreatment drills are available (optional kit) for this procedure. The post is triple-tiered with a positive seating head in the second tier. Both the head and the shank are undercut to provide maximum retention. Thirteen consultants used EDS’ AccessPost in restoring over 100 non-vital anterior and posterior teeth. Positive Features EDS’ AccessPost is easy to use and requires a minimum number of steps. The drills and reamers are effective in establishing and shaping the post space. Consultants considered the ability to retrieve a post in certain cases to be an important factor. Length adjustment of the post was easily accomplished and full seating of the post during cementation was excellent. Both observations were attributed to the hollow nature of the post. Composite core material adapts well to the head of the post. Reduction of the metal head during preparation did not present any problems. Consultants' Comment Several consultants noted that the #3 size post is too large for clinical application. Ratings Excellent +++++ Very Good ++++ Good +++ Fair ++ Poor + Cohen BI, Musikant BL, Deutsch AS. The EDS AccessPost and its clinical use. Dentistry Today 1995;May:88-89. The post and core restoration provides a substructure for attachment of the final restoration to the root. Therefore, the ability of a prefabricated post to resist masticatory forces and remain firmly seated in the tooth is critical. The triple tiered parallel passive design of the EDS AccessPost (Essential Dental Systems, S. Hackensack, NJ) allows the dentist maximum retention while distributing functional stresses evenly. This parallel multi-tiered EDS AccessPost system has major mechanical advantages over tapered systems. Parallel


posts translate most forces into well tolerated vertical stresses, while tapered posts translate most forces into lateral stresses which can easily produce root fracture. Since the EDS AccessPost design utilizes a thick-walled hollow tube configuration, the hollow tube allows easy access to the root canal apex. The practitioner has the option to retrieve the post from the infected root canal and retreat the root canal with standard endodontic reamers and files to remove the infections. The patented hollow tube technology allows for the strength of a solid shank post, while enabling the dentist the means of safe post removal when necessary. Condos S, Cohen BI, Pagnillo M, Deutsch AS, Musikant BL. Post removal using a thick-walled hollow tube post design. J Dent Res 1995;74 Abstract 1256:557. The retention of a post into the root is critical for the successful restoration of an endodontically treated tooth. One important feature for the hollow tube post design (EDS’ AccessPost) is to allow easy access to the apex in the event of a failed root canal. A total of 80 EDS AccessPosts (Nos. 0, 1, 2, and 3) comprising eight groups were cemented in root canals with two different luting agents, Flexi-Flow cem with titanium and zinc phosphate cement. Removal of these EDS AccessPosts were then performed with their corresponding retreatment drills as per manufacturer's instructions. None of the samples for the No. 0 and No. 1 EDS AccessPosts were removed by extraction with their corresponding retreatment drills. All these posts were removed by hand with a hemostat, after breakage of the cement seal with their corresponding retreatment drills. 60% (cemented with ZOP) and 40% (cemented with FF) of samples for the No. 2 EDS AccessPosts were removed by extraction with the corresponding retreatment drills. 80% (cemented with ZOP) and 70% (cemented with FF) of samples for the No. 3 EDS AccessPosts were also removed by extraction. All other samples for the No. 2 and 3 EDS AccessPost were removed by hemostat, after breakage of the cement seal. On an average removal of each EDS AccessPost (Nos. 0 and 1) took between 1 and 2 minutes and EDS’ AccessPosts (Nos. 2 and 3) took between 2 and 3 minutes. No root fractures or widening of the root canals were observed for any sample with either technique (removal with hemostat of extraction with the retreatment drill). This was confirmed by visual and radiographic analysis. The EDS AccessPost thick-

walled hollow tube design allows for safe and routine post removal (if necessary) without damage to the tooth. Johnson WT, Leary JM, Boyer DB. Effect of Ultrasonic vibration on post removal in extracted human premolar teeth. J of Endodon 1996;Vol.22, No.9:487-488. The purpose of this study was to determine the effectiveness of ultrasonic vibration in removing ParaPosts from extracted teeth. Paraposts were cemented in premolars to a depth of 9 mm with zinc phosphate cement and the teeth placed in four groups. Group 1 received no vibration. Group 2 received vibration for 4 minutes, group 3 received vibration for 12 minutes. and group 4 received vibration for 16 minutes. Tensile forces were applied to posts and mean dislodgment forces compared. The mean force (kg) required to dislodge the ParaPost in group 1 was 24.92+ 1.64; in group 2, 25.01+ 1.80; in group 3, 24.08+ 2.29; and in group 4, 12.41+ 2.60. There was a significant difference between group 4 and groups 1 to 3 (p= 0.0003). Results of this study indicate that 16 minutes ultrasonic vibration is an effective method for removing ParaPost from human premolar teeth. In an article by Cohen et al. (page 3 column 1 and page 6 column 1) entitled "Post removal using a thick-walled hollow tube post design" examines our passive post system EDS’ AccessPost, in which we reported that on average, removal of each EDS AccessPost Nos. 2 and 3 took between 2 and 3 minutes. This compares favorably to the results of Johnson et al (16 minutes). Cohen BI, Musikant BL, Deutsch AS. Clinical use of the AccessPost system. Dental News 1996;Vol.III, No.IV:23-26. The post and core restoration provides a substructure for attachment of the final restoration to the root. Therefore, the ability of a prefabricated post to resist masticatory forces and remain firmly seated in the tooth is critical. The triple tiered parallel passive design of the EDS AccessPost allows the dentist maximum retention while distributing functional stresses evenly. Since the EDS AccessPost design utilizes a thick-walled hollow tube configuration, the hollow tube allows easy access to the root canal apex. Therefore, the EDS AccessPost system allows the practitioner to place a stable parallel multi-tiered post with grooved dentin for enhanced retention and in the event of a


failed root canal this post can be removed with no harm to the root in a safe and predictable manner. Cohen BI, Pagnillo M, Condos S, Deutsch AS. Comparison of the torsional forces for seven endodontic post systems. J Prosthet Dent 1995;74:350-357. Increased resistance to torsional forces is an important factor in the restoration of the endodontically treated tooth. In this study, seven different post designs (Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World Post, Vlock and Dentatus post) were cemented into tooth roots using two different post cements (Zinc phosphate and Flexi-Flow). This resulted in 11 different groupings which were subjected to torsional forces in the clockwise direction.In addition, two different directions were used (clockwise and counterclockwise) for the Flexi-Post and Flexi-Flange systems cemented with ZOP and Flexi-Flow. Torsional forces for the groups studied, ranged from 17 oz-inches (Dentatus / ZOP) to 81 oz-inches (Flexi-Post / ZOP). The threaded posts, Flexi-Post and Flexi-Flange resulted in the highest torsional forces obtained. As a result of torsional testing the heads were displaced from the posts. all other specimens from other groups resulted in removal of the posts (Parapost, EDS’ AccessPost, World Post, Vlock and Dentatus) from their corresponding root canals with no head displacement. Analysis were then carried out suing one-way and two-way analysis of variance (ANOVA), followed by Duncan's multiple range test. The only conclusive differences were between groups 11 (Dentatus/ZOP) and all other groups studied. Cohen BI, Condos S, Musikant BL, Deutsch AS. Pilot study comparing the photoelastic stress distribution for four endodontic post systems. Journal of Oral Rehabilitation 1996;23:679-685. This study compared the stress distribution under function using photelastic blocks for both vertical or compressive loading and oblique loading (on a 26 degree angle) for four post systems, groups 1-4 Flexi-Post, Flexi-Flange, Parapost and EDS’ AccessPost). Three test blocks of photoelastic material were prepared with simulated endodontic canals for each group studied. Specimens were then photographed. Minimal stresses were observed for all the posts studied after cementation in the unloaded state. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost

were favorable under compressive loading at 30 pounds and stress patterns were symmetric over the entire length of the post. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable under oblique loadings of 20 and 30 pounds and stress patterns were symmetric over the entire length of the post. Stress distribution for the ParaPost under compressive loading at 30 pounds showed stress patterns which were asymmetric with concentration of stresses apically as compared to coronally. Stress distribution for the ParaPost under oblique loadings of 20 and 30 pounds were asymmetric with stress concentrated apically as compared to coronally. Cohen BI, Pagnillo M, Condos S, Deutsch AS. Porównanie wytrzymalosci na skrecanie siedmiu róznych typów wkladów koronowo-korzeniowych. Stomatologia Wspólczesna 1997;4(3):194-201. (Paper published in Poland’s Stomatologia Wspólczesna (Polish) comparing the torsional forces for seven endodontic post systems.) Increased resistance to torsional forces is an important factor in the restoration of the endodontically treated tooth. In this study, seven different post designs (Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World Post, Vlock and Dentatus post) were cemented into tooth roots using two different post cements (Zinc phosphate and Flexi-Flow). This resulted in 11 different groupings which were subjected to torsional forces in the clockwise direction. In addition, two different directions were used (clockwise and counterclockwise) for the Flexi-Post and Flexi-Flange systems cemented with ZOP and Flexi-Flow. Torsional forces for the groups studied, ranged from 17 oz-inches (Dentatus/ZOP) to 81 oz-inches (Flexi-Post/ZOP). The threaded posts, Flexi-Post and Flexi-Flange resulted in the highest torsional forces obtained. As a result of torsional testing the heads were displaced from the posts. All other specimens from other groups resulted in removal of the posts (Parapost, EDS’ AccessPost, World Post, Vlock and Dentatus) from their corresponding root canals with no head displacement. Analysis were then carried out using one-way and two-way analysis of variance (ANOVA), followed by Duncan's multiple range test. The only conclusive differences were between groups 11 (Dentatus/ZOP) and all other groups studied. Therefore, no conclusive differences in mean torque was observed for Flexi-Post, Flexi-Flange, ParaPost, EDS’ AccessPost, World post


and Vlock post regardless of cement and direction of torque used. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Cyclic Fatigue Testing of Five Endodontic Post Designs Supported by Four Core Materials. J Prosthet Dent 1997;78(4):458-64. This pilot study examined the cyclic fatigue of five endodontic post systems (AccessPost, Flexi-Flange, Flexi-Post, ParaPost, and Vlock) with four core materials (Tytin silver amalgam, Ti-Core, Ketac-Silver and G-C Miracle Mix). In vitro cyclic fatigue was performed with a machine designed to simulate masticatory fatigue forces. An instantaneous force of 22.2 N (5 pounds) was applied to each post and core combination for a test configuration of 4,000,000 repetitions, or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way analysis of variance (ANOVA) was used to compare groups. All posts/core samples with Ti-Core composite and Tytin silver amalgam completed the test with no failures. All posts/core samples with Ketac-Silver material failed before the 4,000,000 test cycle configuration and all failures were core failures. All post/core samples with G-C Miracle Mix material failed in a similar manner. Newman-Keuls multiple comparison test illustrated that, with this simulated fatigue test, Ti-Core material and Tytin silver amalgam were superior to both G-C Miracle Mix and Ketac-Silver materials. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of Three Endodontic Posts Cemented with Five Different Types of Dental Cements. J Prosthet Dent 1998;79(5):520-525. The purpose of this study was to compare the retentive values of three different posts (Flexi-Post, EDS’ AccessPost, and ParaPost) cemented with five different cements (Flexi-Flow, zinc phosphate, Advance, Duet, and Ketac-Cem) plus a control group that consisted of a Flexi-Post No. 2 dowel without cement. A total of 160 recently extracted human single-rooted teeth with crowns removed at the cementoenamel junction were divided into 16 groups with 10 samples per group. Post holes were prepared according to manufacturers' instructions. Posts were then cemented with either Flexi-Flow, zinc phosphate, Advance, Duet, or Ketac-Cem cements. Each sample was placed into a specialized jig and on a tensile testing machine with

crosshead speed of 0.638 cm/min applied until failure. A two-way analysis of variance and Newman-Keuls multiple range comparison tests were performed for all cemented groups. A one-way analysis of variance and a Student-Newman-Keuls multiple range comparison test was performed only for the groups with the Flexi-Post dowel, this included the no cement condition. Results were consider to be statistically significant if p<0.05. The Flexi-Post dowel with Flexi-Flow Natural cement obtained the highest retentive value of 303.91 pounds. ParaPost dowel with Duet cement had the lowest retention value of 21.23 pounds. The Flexi-Post dowel had higher mean retention than did EDS’ AccessPost or ParaPost dowels, and EDS’ AccessPost dowel was higher than ParaPost dowel. Flexi-Flow cement had the highest overall mean retention followed, in decreasing order by zinc phosphate, Advance, Ketac-Cem, and Duet cements. Flexi-Post dowel was the most retentive post studied with values ranging from 303.91 pounds with Flexi-Flow Natural cements to 150.93 pounds without cement. Flexi-Flow cements had a higher overall mean retention than other cements studied. Epstein, PL, Epstein, DD. Overdentures: A Review and Update. GP-The Journal of New York State Academy of General Dentistry 1997;Sept:14-15. The Flexi-Overdenture: A stainless steel male on a screw-type, split-shank, flange post (to reduce internal stressed) in the root, with a nylon cap female is luted into the denture. Load bearing by nature, and limited, with rotational resiliency. This supraradicular system has excellent retention. The EDS AccessPost Overdenture provides a method for simplified endodontic retreatment should it be necessary. 1998 CRA Dental Product Buying Guide.CRA-Clinical Research Associates Newsletter. 1998;22(1):2&4. Products which were highly rated after clinical field trials: EDS’ AccessPost Overdenture- Excellent overall grade & purchase indicated


Effects of three bonding systems on the torsional resistance of titanium-reinforced composite cores supported by two post designs. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. J Prosth Dent 1999;81(6):678-683. The resistance of an endodontic treated tooth to torsional forces is critical for the long-term survivability of the restoration. Two designs (EDS’ AccessPost and ParaPost dowels) with a core (Ti-Core, a titanium reinforced core material) utilizing four different bonding conditions (AllBond-2, ScotchBond Multi-Purpose, Tenure A & B, and without a bonding agent) resulted in eight different grouping. A total of 80 specimens were prepared and subjected to clockwise torsional forces until failure. The torsional values ranged from 53.31 inch x ounce (ParaPost/ScotchBond Multi-Purpose) to 72.31 inch x once (EDS’ AccessPost/ScotchBond Multi-Purpose). The results of the two-way of analysis of variance (two-way ANOVA) showed that there was no significant difference between post or type of bonding system used. The use of a multi-step bonding agent had no significant effect on the torsional resistance of a core supported by a passive endodontic post. On the basis of the results of this vitro torsional study, the following conclusions were made; 1) A bonding agent has no significant effect on the torsional resistance of a post and core restoration, 2) There was no significant difference in the torsional resistance between the EDS AccessPost post system and ParaPost post system, 3) An EDS AccessPost dowel bonded with ScotchBond Multi-Purpose produced the highest torsional resistance (72.31 inch x ounce). The Effects of Bonding Agents on Torsional Resistance of Post and Cores. Deutsch AS, Cohen BI, Pagnillo MK, Newman I, Musikant BL. J Dent Research. (IADR Abstract #1713) 1999;78:320. The purpose of this study was investigate the effects of bonding of the torsional resistance of two passive post designs (EDS’ AccessPost and the ParaPost dowels) with a titanium reinforced core (Ti-Core) utilizing four different bonding conditions (AllBond-2, ScotchBond Multi-Purpose, Tenure A&B, and without a bonding agent). Torsional resistance is an important factor in the long-term survivability of an endodontically treated tooth, but there are no studies measuring the torsional value of a prefabricated post with a composite core. This in vitro study was divided into eight groups with

10 specimens per group. A total of 80 recently exacted single-rooted human teeth with their crowns removed at the cementoenamel junction were used. Stainless steel EDS’ AccessPost No. 2 (Essential Dental Systems) and the equivalent stainless steel ParaPost No. P-44-6 (Whaledent/Coltene) endodontic dowels were used. All endodontic post holes were prepared according to manufacturer’s recommendations. Placement of the bonding agent was performed as per manufacturer’s instructions. The two control groups were etch with a 37.5% phosphoric acid (ScotchBond acid etchant) for seconds and then rinsed with distilled water. The cores were allowed to cure for one hour before trimming and being placed into acrylic blocks (Formatray). The test specimens were then placed into a 100% humidity environment for a week before testing. The test specimens were then placed in a special jig and a custom vise was tighten onto the core. The torsional force was then measured on a Lebow 1102-200 torque transducer apparatus (Eaton Corp.) and the force was recorded in inch x ounces on a Hewlett Packard 7015B X-Y recorder. A two-way analysis of variance (ANOVA) was used to compare mean torque across posts and bonds and to examine the interaction between post and bond. All results were considered statistically significant if p < 0.05. The torsional values ranged from 53.31 inch x ounce (ParaPost/ScotchBond Multi-Purpose) to 72.31 inch x ounce (EDS’ AccessPost/ScotchBond Multi-Purpose). The two-way ANOVA showed no significant interaction between post and bond system and also showed no significant differences between posts or between bonding agents. The bonding agents used in this study have no significant effect on the torsional resistance of a post and core restoration. There was no significant different in the torsional resistance between the EDS AccessPost post system and ParaPost post system. An EDS AccessPost dowel bonded with ScotchBond Multi-Purpose produced the highest torsional resistance (72.31 inch x ounce). Musikant BL, Cohen BI, Deutsch AS. The Clinical Use of an AccessPost Overdenture Attachment. Dent Today 1998;17(8):120-121. The EDS AccessPost Overdenture Attachment is a passive, parallel, multitiered post that has a ball attachment on its coronal end. It supports a nylon attachment that is incorporated into an overdenture. Alternatively, and for great ease of replacement, a


threaded version of the nylon attachment can be threaded into an EZ-Change metal receptacle that in turn is incorporated into the denture. The post allows the dentist to utilize remaining roots to support the retention of a denture. The ball and the nylon attachment sit low on the root reducing the height of the lever arm to an absolute minimum. The forces of occlusion, traveling through a short lever arm are generally well tolerated by the residual root. The EDS AccessPost Overdenture Attachment has the unique design of being a hollow tube allowing for its atraumatic removal if necessary. Use of a dentin grooving drill prior to post cementation increases retention of this passive post to 90 pounds as high as any recorded passive post. The triple tiered design distributes functional stresses in a uniform pattern preventing the stress concentration in anyone location. When the nylon EZ-Change insert attachment wears out, it is a simple matter to use the EZ-Change wrench to unthread the worn out nylon insert cap from the metal keeper and thread in a new one. The EDS AccessPost Overdenture attachment offers the dentist a way to increase the retention of dentures that is atraumatic to the supporting root. The EZ-Change attachment adds further convenience by allowing a quick way to replace a worn-out attachment. Post and core combinations tested for retention. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Dental Abstracts 1998;43(5):250. Retention of posts is a major factor in successful treatment involving endodontic therapy and post and core restoration. This study compared the retention of three endodontic posts cemented with five different materials and compared them with a control. Specimens were 160 recently extracted single-rooted teeth. Crowns removed at the cemento-enamel junction and teeth were divided into 16 groups of 10. One group was treated with a Flexi-Post No. 2 dowel without cement (control). The appropriate post hole was made according to manufacturers instructions for the three stainless steel dowels tested: Flexi-Post, EDS’ AccessPost, and ParaPost. Five groups of each dowel were used to test each of the cements: Flexi-Flow Natural (resin composite), ZOP (zinc phosphate), Advance (hybrid glass ionomer), Duet (hybrid glass ionomer), and Ketac-Cem (glass ionomer). Specimens were tensile tested until the post was removed. Results were analyzed by post and by the post/cement interactions.

The Flexi-Post dowel had the highest mean retention rate, followed by EDS’ AccessPost. The Flexi-Post dowel cemented with Flexi-Flow Natural had the highest retentive value (303.91 pounds). The ParaPost dowel cemented with Duet had the lowest value (21.23 pounds). Flexi-Flow cement had the highest total mean retention, followed by ZOP, Advance, Ketac-Cem, and Duet. Retention was influenced significantly by both the post and cement used. Post-related differences did not remain constant when different cements were used. Combinations of posts and cements demonstrated significant differences in retention. Pagnillo MK, Cohen BI, Epstein D, Epstein P. J Comparison of the Retentive Properties of Six Prefabricated Overdenture Systems. J Dent Research. (IADR Abstract #2917) 1999;78:470. The purpose of this in vitro study was to compared how much retentive force was required to remove six different prefabricated overdenture attachment designs over a 2,000 pull test configuration. This study consisted of six groups with 10 specimens per group; group 1) EDS’ AccessPost Overdenture/EZ-Change system, group 2) Flexi-Overdenture/EZ-Change system, group 3) ERA/grey caps, group 4) ERA/white caps, group 5) OSO system, and group 6) ZAAG system. The pull resistance was measured in pounds with a force gauge (Shimpo Force Gauge) over a 2,000 pull cycle (pull 1, 10, 50, 100, 500, 1000, 1500, and 2000). Results ranged from 5.63 to 12.01 pounds for the first pulls to 1.45 to 2.73 pounds for the 2,000 pull (last pull). The two dependent variables were Absolute Force (AF) and Relative Force (RF). Repeated measures analysis of variance (RMANOVA) was used to compare the effects of post and pull. A standard one-way ANOVA was used to compare AF and RF at pull 2,000th, followed by a Student-Newman-Keuls (SNK) multiple comparisons test. There was a significant difference if p<0.05. Retention values for the first and last pull were as follows: Pull Access Flexi-OVD OSO ERA ERA ZAAG Post Grey White

OVD

1 8.68 12.01 5.63 12.00 6.65 6.22

±3.46 lbs ±3.61 lbs ±2.00 lbs ±5.09 lbs ±1.51 lbs ±2.90 lbs

2,000 2.28 1.88 2.7 1.45 1.98 2.60

±1.85 lbs ±0.77 lbs ±1.18 lbs ±0.50 lbs ±0.67 lbs ±0.87 lbs

For AF there was no significant difference between posts in mean force required on the 2,000th pull.


However, there was a significant difference between posts (p<0.001) mean in the way AF changed over pulls. For Relative Force (RF), RMANOVA also showed an interaction between pull number and post (p<0.0008). It was concluded from the results that there were three groupings: OSO and ZAAG systems which had the least rate of change and the lowest first pull retention, the ERA white and the EDS AccessPost Overdenture having the middle rate of change, and the Flexi-Overdenture and ERA grey having the largest rate of change. The Flexi-Overdenture gave the highest retention value of 12.01 pounds for the first pull and OSO system gave the lowest retention value of 5.63 pounds for the first pull. The retention (AF) at the end of the 2000th pull configuration were statistically similar for all groups studied. Deutsch AS, Cohen BI, Pagnillo MK, Newman I, Musikant BL. Post-head Retention of Two Core Materials Using Three Post Designs. J Dent Res 2000;79:546 (Abstract 3222). The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The post heads were then placed into the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results

of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Penugonda B, Cohen BI, Pagnillo MK, Schulman A, Hittelman E. Torsional Forces on Crowns supported by Post-Core Restorations. J Dent Res 2000;79:546 (Abstract 3223). The purpose of this in vitro study was to investigate the effect of torsion on a crown supported by a titanium-reinforced composite core material (Ti-Core core material) and three different endodontic post system (Flexi-Post, EDS’ AccessPost and ParaPost). This study was divided into three groups with 10 specimens per group. A total of 30 recently extracted human single-rooted (incisors) teeth with their crowns removed at the cementoenamel junction were used. Post-hole preparations were created following manufacturer’s instructions. The post-holes were prepared to a depth of 10 mm. All posts were cemented in place using Flexi-Flow cement. Scotchbond Multi-Purpose bonding agent was used as the bonding system for all groups. All cores were fabricated with Ti-Core with titanium core build-up material using hard copper bands as the matrix. The Ti-Core core build-up material was placed and allowed set for one hour before being shaped and trimmed with 0.5 mm shoulder and beveled on tooth using diamond burs. Polyvinyl siloxane (PVS) impressions of the teeth were taken to fabricate metal crowns on epoxy dies. Polished metal crowns were cemented with zinc phosphate cement. The test specimens were then placed into acrylic blocks and


stored in 100% humidity for 1 week before being tested. The test specimens were placed in a special jig and a clockwise torsional force was applied. The torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorder in inch x ounces. A one-way ANOVA followed by a Student-Newman-Keuls (SNK) and Scheffe comparison tests were performed and results were considered significant if p<0.05. Results of the mean torque loading was as follows; Group 1, Flexi-Post 162.2 ± 52.2 in x oz, Group 2, EDS’ AccessPost 77.2 ± 30.3 in x oz, and Group 3, ParaPost 60.9 ± 28.4 in x oz. The results of the ANOVA revealed a significant difference p<0.001. The SNK and Scheffe comparison test revealed that the Flexi-Post group had significantly greater resistance to torque loading than the EDS AccessPost and ParaPost groups, which were statistically similar to each other. It was concluded that post design has an effect on torsional resistance of a crown supported by a titanium reinforced core build-up and post. The active threaded split-shank design of the Flexi-Post dowel offers greater resistance to torsional loading than the passive posts studied. Stockton LW, Williams PT. Retention and Shear Bond Strength of Two Post Systems. Oper Dent 1999;24:210-216. The purpose of this study was to compare the retention and shear strength of teeth restored with the Para Plus post (P) and the C post (C1 and C2) systems. Twenty-four P, C1, and C2 posts each were placed 7 mm into recently extracted and endodontically treated maxillary anterior roots and luted with Ketac-Cem and Bis-Core respectively. In addition, 13 samples of each post type had a Bis-Core composite core placed. The tensile retention strength of the post and shear strength of the post and core restorations when the core was loaded buccolingually at 45º to the roots’ long axis were determined at a strain rate of 1.3 mm/min. The C2 posts required significantly more tensile force (P<0.001) to remove them than the P or C1 posts. The shear strength of the post/core restorations was not significantly different (P<0.04). The C1 restorations had 12 root fractures, the C2 restorations had 11 root fractures, and the P samples had six root fractures. It was concluded that the lack of stiffness of the C post adversely affected the success of these restorations. The author also concludes, the use of C posts may be undesirable for most cases.

Cohen BI, Pagnillo MK, Newman I, Musikant L, Deutsch AS. Pilot study of the cyclic fatigue characteristics of five endodontic posts with four core materials. J Oral Rehabil 2000;27:83-92. This pilot study concerned the cyclic fatigue of five different endodontic post systems. (EDS’ AccessPost, Flexi-Flange, Flexi-Post, ParaPost and Vlock with four different core materials (Tytin Silver amalgam, Ti-Core, Ketac-Silver and G-C Miracle Mix). In vitro cyclic fatigue was performed using a fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 lbs. was applied to each post and core combination for a test configuration of 4,000,000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way ANOVA was used to compare groups. All posts/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4,000,000 test cycle without failures. All post /core samples with Ketac-Silver failed before the 4,000,000 test cycle test cycle configuration, all as a result of core failures. All post/core samples with G-C Miracle Mix failed in a similar way. The Newman-Keuls multiple comparison test illustrated that Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Similar fatigue test results are found in the literature. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. Retention of a core material supported by three post head designs. J Prosthet Dent 2000;83(6):624-628. The purpose of this study was to compare the retention of three different endodontic post head designs (Flexi-Post, EDS’ AccessPost, and Cerapost) with two different core materials (Ti-Core and GC Miracle Mix). This study was divided into six (6) groups with 10 specimens per group. Only stainless steel posts were used for EDS’ AccessPost and Flexi-Post and Cerapost is a ceramic post design. Core materials were mixed according to manufacturer’s instructions. For Ti-Core core material equal parts of base and catalyst were mixed together into a homogenous mass. For Miracle Mix core material two scoops of powder and four drops of liquid were mixed together into a homogenous mass. The mixed core material was placed into molds with the dimension of 5 mm high and diameter of 8 mm using a centrix syringe. The post heads were then placed into


the core material and allowed to set for 1 hour before being placed into a 100% humidity environment at room temperature for 24 hours. The test specimens were then placed in a special jig and the retention strength was tested using a 810 MTS Material Testing System with a crosshead speed of 0.638 cm/min until failure occurred. Failure occurred when the post was removed from core material or post failure occurred. The study was designed as a 3x2 factorial. A two-way analysis of variance (ANOVA) was used to compare mean retention among the six post/core groups and results were considered significant if p <0.05. Results of the retention test were as follows; Flexi-Post/Ti-Core 220.0 pounds, Flexi-Post/Miracle Mix 43.4 pounds, EDS’ AccessPost/Ti-Core 212.7 pounds, EDS’ AccessPost/Miracle Mix 61.6 pounds, Cerapost/Ti-Core 41.8 pounds, and Cerapost/Miracle Mix 7.5 pounds. Results of the ANOVA revealed a highly significant interaction between post and core (p<0.0001). The retention of the core materials to the head design for the EDS’ AccessPost and Flexi-Post dowels was highly significantly greater then the core retention to the Cerapost dowel. The retention strength of Ti-Core core material to the posts studied were significantly greater then the retention of Miracle Mix core material to the posts. It was concluded, that the post head designs of the stainless steel EDS’ AccessPost and Flexi-Post dowels offered greater statistical retention then the smooth ceramic head design of the Cerapost dowel. It was also concluded that the composite core material, Ti-Core, offers statistically more retentive strength then the glass ionomer material, Miracle Mix. Cohen BI, Penugonda B, Pagnillo MK, Schulman A, Hittelman E. Torsional resistance of crowns cemented to composite cores involving three stainless steel endodontic post designs. J Prosthet Dent 2000;84(1):38-42. The purpose of this in vitro study was to investigate the effect of torsion on a crown supported by a titanium-reinforced composite core material (Ti-Core core material) and three different endodontic post system (Flexi-Post, EDS’ AccessPost and ParaPost). This study was divided into three groups with 10 specimens per group. A total of 30 recently extracted human single-rooted (incisors) teeth with their crowns removed at the cementoenamel junction were used. Post-hole preparations were created following manufacturer’s instructions. The post-holes were prepared to a depth of

10 mm. All posts were cemented in place using Flexi-Flow cement. Scotchbond Multi-Purpose bonding agent was used as the bonding system for all groups. All cores were fabricated with Ti-Core with titanium core build-up material using hard copper bands as the matrix. The Ti-Core core build-up material was placed and allowed set for one hour before being shaped and trimmed with 0.5 mm shoulder and beveled on tooth using diamond burs. Polyvinyl siloxane (PVS) impressions of the teeth were taken to fabricate metal crowns on epoxy dies. Polished metal crowns were cemented with zinc phosphate cement. The test specimens were then placed into acrylic blocks and stored in 100% humidity for 1 week before being tested. The test specimens were placed in a special jig and a clockwise torsional force was applied. The torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorder in inch x ounces. A one-way ANOVA followed by a Student-Newman-Keuls (SNK) and Scheffe comparison tests were performed and results were considered significant if p<0.05. Results of the mean torque loading was as follows; Group 1, Flexi-Post 162.2 ± 52.2 in x oz, Group 2, EDS’ AccessPost 77.2 ± 30.3 in x oz, and Group 3, ParaPost 60.9 ± 28.4 in x oz. The results of the ANOVA revealed a significant difference p<0.001. The SNK and Scheffe comparison test revealed that the Flexi-Post group had significantly greater resistance to torque loading than the EDS AccessPost and ParaPost groups, which were statistically similar to each other. It was concluded that post design has an effect on torsional resistance of a crown supported by a titanium reinforced core build-up and post. The active threaded split-shank design of the Flexi-Post dowel offers greater resistance to torsional loading than the passive posts studied. Epstein DD, Epstein PL, Cohen BI, Pagnillo MK. A comparison of the retentive properties of six different overdenture attachment systems. J Prosthet Dent 1999;82:579-84. The in vitro retention measured in pounds, of six overdenture anchor attachment systems, EDS’ AccessPost Overdenture/EZ-Change, Flexi-Overdenture/EZ-Change, ERA white, and ERA Grey, O-SO and ZAAG were tested of a cycle of 2000 “pulls”. Records of the pounds of force necessary to separate each system were made at the beginning of the


testing, at pull 10, and then at every 50th pull until the 2000th pull was attained. The pulls were all performed manually using a Shimpo Force Gauge. Absolute Force (AF) and Retentive Force (RF) were compared, AF being the force required at any pull to separate the overdenture device, while RF is the force required at any pull expressed as a percent of the force required at the first pull. There was considerable difference of the force required at pull 1 for the ERA white, O-SO and ZAAG anchor systems, then the EDS AccessPost Overdenture and finally the Flexi-Overdenture and ERA Grey. However, at pull 2000, there was no statistical difference between any of the attachments studied. The amount of force necessary to offer functional retention to a specific patient wearing an overdenture will vary considerably, depending first upon the many factors in fabricating the overdenture, and then the age, strength, musculature and even the expectations of the patient. Cohen BI, Pagnillo M, Newman I, Musikant BL, Deutsch AS. Badania wytrzymalosciowe pieciu róznych wkladów koronowo-korzeniowych zastosowanych z czterema róznymi materialami do odbudowy zrebu koronowego. Przeglad Stomatologiczny 2000;January:18-21. (Published in Polish: Pilot study of the cyclic fatigue characteristics of five endodontic posts with four core materials.) This pilot study concerned the cyclic fatigue of five different endodontic post systems. (EDS’ AccessPost, Flexi-Flange, Flexi-Post, ParaPost and Vlock with four different core materials (Tytin Silver amalgam, Ti-Core, Ketac-Silver and G-C Miracle Mix). In vitro cyclic fatigue was performed using a fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 lbs. was applied to each post and core combination for a test configuration of 4,000,000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way ANOVA was used to compare groups. All posts/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4,000,000 test cycle without failures. All post /core samples with Ketac-Silver failed before the 4,000,000 test cycle test cycle configuration, all as a result of core failures. All post/core samples with G-C Miracle Mix failed in a similar way. The Newman-Keuls multiple comparison test illustrated that

Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Similar fatigue test results are found in the literature. Cohen BI, Condos S, Musikant BL, Deutsch AS. Porównanie rozkladu naprezen dla czterech rodzajów wkladów koronowo-korzeniowych za pomoca badania elastooptycznego. Compendium Stomatologli 2000;3:21-24. (Article Published in Polish: Pilot study comparing the photoelastic stress distribution for four endodontic post systems.) This study compared the stress distribution under function using photelastic blocks for both vertical or compressive loading and oblique loading (on a 26 degree angle) for four post systems, groups 1-4 Flexi-Post, Flexi-Flange, Parapost and EDS’ AccessPost. Three test blocks of photoelastic material were prepared with simulated endodontic canals for each group studied. Specimens were then photographed. Minimal stresses were observed for all the posts studied after cementation in the unloaded state. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable under compressive loading at 30 pounds and stress patterns were symmetric over the entire length of the post. Stress distribution for the Flexi-Post, Flexi-Flange and EDS’ AccessPost were favorable under oblique loadings of 20 and 30 pounds and stress patterns were symmetric over the entire length of the post. Stress distribution for the ParaPost under compressive loading at 30 pounds showed stress patterns which were asymmetric with concentration of stresses apically as compared to coronally. Stress distribution for the ParaPost under oblique loadings of 20 and 30 pounds were asymmetric with stress concentrated apically as compared to coronally. Phan DC, Nagy WW, Dhuru VB, Karczewski MB, Ziebert AJ. Effect of Sterilization and Disinfection Procedures on Prefabricated Posts. J Den Res (Abstract 1259), 2001;80:1259. A prefabricated post may be inserted in the canal and examined until the correct size is chosen. For those posts that were tried but not used, a potential for blood borne contamination exists. This study evaluated six prefabricated post types for alteration in surface detail or other visible morphological change after disinfection and sterilization. Three metallic and three non-metallic post types were evaluated, ParaPost - titanium, Flexi-


Post - stainless steel , Filpost - pure titanium, C-Post - carbon fiber, FiberKor - glass fiber, and the Cosmo Post - zirconium oxide. Two posts of each type were subjected to three cycles of disinfection (alkaline glutaraldhyde, phenolic, sodium hypochorite) and sterilization (steam - regular and flash, dry heat, ethylene oxide, chemical vapor). Specimens were examined with a 10X optical microscope and a 550X (SEM), and baseline and post exposure photomicrographs were made. The white FibreKor post exhibited a greenish hue when removed from the phenolic disinfection solution suggesting the porous nature of the post body, and the post was slightly darkened after dry heat sterilization at 165° C, suggesting additional polymerization of the resin matrix. Metallic and zirconium oxide posts are physically stable when subject to three cycles of commonly used dental office disinfection and sterilization protocol. Fiber/resin posts show surface changes, and steam or ethylene oxide sterilization is recommended. Finger WJ, Ahlstrand W, Fritz UB. Evaluation of the radiopacity of fiber-reinforced resin posts. J Dent Res (Abstract 1113) 2001;80:666. To determine the radiopacity of resin fiber posts before and after cementation in extracted human canines, and to evaluate their appearance on dental radiographs by clinical acceptability scores. One titanium and 7 resin fiber posts were investigated: Komet/Titanium (TIT), Æstheti-Plus (AES), FiberKor (FIK), Light-post/rtd (LPR), LightPost/Dentatus (LPD), Mirafit (MIR), Snowlight (SNL), and Snowpost (SNP). Radiographs of the separate posts and of the posts seated with Panavia 21 EX in endodontically treated prepared canine roots were produced. The radiodensities were determined with a densitometer and expressed in mm Al-equivalents. Sixteen radiographs of the cemented posts (two of each brand) were presented in random order to 20 dental practitioners for ranking by decreasing radiodensity and characterization of the radiographic appearance on a 5-step scale: 1 (good), 2 (adequate), 3 (acceptable), 4 (not acceptable), 5 (no radiopacity). The data was statistically analyzed by one-way ANOVA and Duncan's post-hoc test at p>0.05. Ranking of the separate posts: TIT > SNL, SNP > FIK > LPR, LPD > MIR. Ranking of the cemented posts: TIT > SNL, SNP > FIK, LPD, AES, MIR, LPR. The dentist’ ranking from highest to lowest radiopacity was: TIT > SNL, SNP > FIK > LPD, MIR > LPR > AES.

The ranking clinical acceptability was: TIT(1.0) > SNL(2.2), SNP(2.5) > FIK(3.3.) > LPD(4.2), MIR(4.2), LPR(4.6), AES(4.6). The results showed that resin fiber posts are considerably less radiopaque than titanium (metallic) posts. Only three of the seven fiber posts evaluated fulfilled the requirement of acceptable radiographic appearance. Schmage P, Sohn J, Nergiz I, Platzer U. Various Conditioning Methods Influencing the Retention of Root Posts. J Dent Res (Abstract 1305) 2001;80:690. In order to achieve a high root post retention the usage of composites for the post fixation was advised. For the various composite cements different conditioning methods are recommended by the manufacturers, nevertheless the effects of not following them are unclear. This study aimed to measure the bonding strengths of passive tapered root posts inserted with composite cements using different conditioning methods. The root canals of 140 extracted teeth were prepared for sandblasted Titanium Erlangen posts (Brasseler USA, Savannah, USA) of size 11/ length 12mm. Groups of 10 posts were fixed using four composites (Compolute, ESPE, Seefeld, Germany; Flexi-Flow Cem. Essential Dental Systems, NJ, USA; Panavia 21 EX, Kurary, Osaka, Japan: Twinlook, Heraeus-Kulzer, Dormagen, Germany) and the following three conditioning methods respectively: no conditioning, etching, etching/ bonding. Panavia was also used as recommended with a primer. For comparison 10 posts were inserted using a conventional zincphosphate cement (Tenet, Vivadent, Schaan, FL). A tensile force test (Instron 1026) was performed after moist storage for 24 hours and thermocycling. The results were statistically analyzed using the ANOVA-test and the Scheffé-correction. The highest retentive strengths corresponded with the manufacturers conditioning recommendations for Compolute (352±76N) and for Twinlook (430N±78N) using etching and bonding and for Flexi-Flow using no conditioner (475N±104N). The results using Panavia with etching and bonding (442N±97N) instead of primer (375N±77N) did not prove to be statistically significantly different. In all other groups the results decreased significantly if he manufacturers instructions for conditioning were not followed. There were no significant difference between the composites and the conventional cement (414N±102N). Flexi-Flow composite cement resulted in statistically similar


retention and the use of Flexi-Flow composite was simpler where no conditioner was needed. Flexi-Flow also had the added benefit of being the only composite cement with 5+ years of documented fluoride release data. Rathke A, Heintze SD, Zappini G. Cyclic Loading of Incisors Restored with Different Post Systems. J Dent Res (Abstract 1431) 2001;80:705. Occlusal stress may result in the failure of post and core build-ups. The aim of this study was to evaluate the fatigue resistance of prefabricated posts covered with metal copings by submitting them to cyclic loading. Thirty-five extracted human maxillary incisors of similar dimensions were decapitated, root filed and embedded in acrylic blocks with simulated periodontal ligaments. Post spaces were prepared to a depth of 8 mm. Five groups of 7 specimens each were compared: a 1.5 mm diameter titanium post (Mooster, CM) (A), a 1.7 mm diameter zirconia post (Cosmopost, Ivoclar) (B), a 1.4 mm diameter fiber post (Aesthetiplus, RTD) (C), and experimental fiber posts of 1.5mm (D) and 2.0 mm in diameter (E). The posts were cemented with zinc phosphate cement. The specimens were stored 37ºC water for 48 hours, then cyclically loaded with 25N peak load at an angle of 45º to the axial direction in an universal testing machine (Zwick 1465). Every 250 cycles (frequency of 0.2 Hz), the peak was increased by 25 N until post failure. Failure modes were yielding (A) and post fracture (B, C, D, E). The mean loading cycles and standard deviations were: 1475±66 (A), 1045±93 (B), 767±69 (C), 761±134 (D), and 1160±143 (E). The mean equivalent loads and standard deviations were: 128 ± 10 N (A), 68 ± 12 N (B), 40 ± 6 N (C), 40 ± 12 N (D), and 83 ± 18 N. (E). For both variables, ANOVA post Tukey test showed significant differences (p<0.001) between (A) and other groups. No statistically significant differences (p>0.05) were found between (C) and (D) or (B) and (E). Metal posts demonstrated higher fatigue resistance than non-metal posts. Cimma R, Farina GA, Damiano F. Ricostruzioni Preprotesiche Con Perni Endocanalari Cilindrici: Seianni Di Esperienza Clinica. Doctor OS 2001;12(7):939-951. (Preprosthetic Reconstructions with Cylindrical Endodontic Post: Six Years of Clinical Experience. Published in Italian)

The quantity of 500 reconstructed teeth were evaluated to determine the success rate of an endodontic restorative system. All teeth were restored using EDS’ AccessPost, a parallel sided multiple tiered post. Posts were cemented with Flexi-Flow titanium reinforced, fluoride releasing, resin composite cement and core build-ups were preformed using Ti-Core titanium reinforced, fluoride releasing, resin composite core material. 272 teeth were restored in the upper jaw and 228 in the lower jaw. In the course of this six year study, 15 failures occurred - none caused tooth loss. In fact 14 failures were due to separations of the reconstruction together with the post and in one case there was the fracture of the post. The results demonstrate the clinical validity of this restorative system. Newman MP, Yaman P, Dennison J, Rafter M, Billy E. Fracture resistance of endodontically treated teeth restored with composite posts. J Prosthet Dent 2003;89:360-367. The purpose of this study was to compare the effect of 3 fiber-reinforced composite post systems on the fracture resistance and mode of failure of endodontically treated teeth. Ninety maxillary central incisors were divided into 8 experimental groups and 1 stainless steel control group of 10 specimens each. Eighty teeth were assigned to 2 main experimental groups called “narrow” and “flared” canals. For the narrow canal group, post spaces were prepared with the corresponding diameter, respectively. For the flared canals group thin-walled canals were simulated. Teeth for the flared canals were restored with the same post but were cemented into tapered 2 mm wide canals created with a tapered diamond bur. Specimens were loaded to failure with a universal testing machine at a crosshead speed of 0.05 cm/min until failure occurred. The data was analyzed with analysis of variance and Student t tests (P<0.05). For the narrow canal, the mean load ranged form a low of 4.55 (±1.49)kg for the Ribbond standard to a high of 12.9 (±1.64)kg for the Luscent anchors. The stainless steel control group had the highest load value (18.33 (±3.27)kg. For the flared canal the low mean was 9.04 (±1.76)kg for FibreKor and the high was equal for both Luscent anchors and Ribbond standard, 12.87 (±2.69) and 12.87 (±3.54), respectively. The results from the study show that the load to failure of the stainless steel posts were significantly stronger than all the composite post studied.

SAFESIDERS® & EZ-FILL® 5/1

SAFESIDERS® & EZ-FILL® SAFESIDERS® is a series of patented, non-circular, non-interrupted, flat-sided endodontic instruments. Recommended for use with or without the Endo-Express reciprocating hand piece. The patented EZ-Fill® SafeSider® system provides space for dentinal debris resulting in fast non-binding access to the apex. Ideal for use with the patented EZ-Fill® Bi-Directional Spiral and Epoxy Root Canal Cement to create an exceptional three dimensional fill. EZ-FILL® is a patented root canal filling system that contains the patented bi-directional spiral & epoxy root canal cement combined with a single point technique has been shown to create a seal equivalent to lateral condensation & thermoplastic gutta percha, both at a cost & time savings. A Comparison of Sealer Placement Techniques in Curved Canal. Hall MC, Clement DJ, Dove SB. J Endodon 1996;22(12):638-642. Sealer placement techniques have not been examined in teeth with curved canals prepared with Lightspeed instruments. Three traditional methods of placing sealer were studied, using 45 extracted human single-rooted teeth, divided into 3 groups of 15 teeth. Root canal preparations were made with Lightspeed nickel-titanium, engine-driven instruments. AH-26 (epoxy root canal cement) sealer was applied with either K-file, lentulo spiral, or master gutta-percha cone. Radiographs were taken after sealer placement and analyzed for amount of canal sealer fill. The teeth were then obturated with laterally condensed gutta-percha, chemically cleared, photographed, and analyzed for total canal wall sealer coverage. The results showed a statistically significant difference in canal sealer fill among the three groups before obturation, but there was no statistical difference in the canal wall coverage among the three groups after obturation. None of the examined methods exceeded an average of 62.5% wall coverage of sealer after obturation. This suggests that complete wall coverage after obturation may not be possible. Lee CQ, Chang Y, Cobb CM, Robinson S, Hellmuth EM. Dimensional Stability of Thermosensitive Gutta-Percha. J Endodon 1997;23(9):579-582. The expansion and shrinkage of four commercial brands of endodontic thermosensitive gutta-percha were evaluated. A modified volume dilatometry technique was used; the

diatometric system (DS) consisted of Pyrex glass capillary tubes and a specimen chamber. Each sample was weighed to 10-4 mg, placed in the specimen chamber, and subjected to vacuum for 45 minutes to eliminate moisture or gases. The DS was gradually heated from 24°C to 80°C and then cooled to 24°C using a well agitated temperature-controlled water bath. In a parallel set of experiments, the DS was heated in the same manner but cooled to body temperature (37°C) in the water bath and the temperature kept stable at 37°C for 24 h. The level of the mercury meniscus within the DS was monitored to determine the percent volume change of each sample at 2°C intervals. All samples expanded as the temperature was elevated and shrank during cooling. The percent volume change for each of the four gutta-percha products, as the temperature was raised to 80°C, ranged from an expansion of +11.62 to +12.25. As the temperature was lowered from 80°C to 24°C, the percent volume change representing shrinkage ranged from -2.22 to -3.53. When the temperature was lowered from 80°C to 37°C, the products continued to exhibit shrinkage for a range of time between 45 minutes and 10 hours before stabilizing at a fixed volume. The final percent volume change for each experiment, with each product, was positive, ranging from +5.50 to +7.20, with discernible differences between products. Cohen BI, Pagnillo MK, Musikant BL, Deutsch AS. The Evaluation of Apical Leakage for Three Endodontic Fill Systems. AGD (General Dentistry) 1998;46(6):618-623. This study evaluated the apical leakage for three endodontic systems; 1) lateral condensation with EZ-Fill's epoxy adhesive, 2) Thermafil with Thermaseal adhesive, and 3) EZ-Fills' Bi-directional reamer with adhesive. This study was divided into of five groups comprising 10 specimens of recently exacted single rooted human teeth for each group. All tooth roots were sealer with nail enamel except 2 mm at the apical end. Each coating was allowed to completely dry for 24 hours before applying the next enamel coat. The test specimens were suspended with the apical end of the tooth was in a 2% methylene blue solution for two weeks. The teeth were then sectioned buccolingual along the long axis with a shape knife. The percentage of leakage was calculated by measuring the length the coronal lip of access on the lingual of the teeth to the most apical end of the canal; that measurement (y) using a binocular microscope at 5x power. The extent of dye penetration from the apex coronally was again


measured with a binocular microscope at 20x power. This measurement was taken as the (x) value. The results were reported as a percentage calculated by dye leakage length divided by the total length of the canal ((x/y)100%). A Kruskal-Wallis non-parametric test was used to compare leakage percentages across the five groups and was considered statistically if p < 0.05/10 = 0.005. Results showed that Lateral Condensation (mean of 4.30%), EZ-Fills’ Bi-directional Reamer (mean of 1.80%), and Thermafil (mean of 3.59%) did not differ from each other but differed from the No Treatment group and the Instrument-Unfilled group. In this study, the EZ-Fills’ Bi-directional reamer technique produced a tighter apical seal than either the lateral condensation and the Thermafil obturation techniques, but they all were not significantly different. EZ-Fills’ Bi-directional reamer is a faster and more economical alternative to lateral condensation and Thermafil obturation. AH-26 Root Canal Sealer, The Endodontist’s Best - Kept Secret: An interview with Marwan Abou-Rass, DDS. Endodontics for GP 2(12);1990:4-6. Endodontics for GP: What are the advantages of using AH-26? Abou-Rass: AH-26 is non-irritating, epoxy resin with excellent tissue tolerance. Because it is not a zinc oxide (ZOE) cement, it will not undergo resorption as quickly as ZOE compounds. Because AH-26 is an epoxy resin, once it sets, it is non-irritating because there is nothing to leak. You have plenty of working time with AH-26, which does not set completely for approximately 24 hours. Abou-Rass (Con’t.): Because AH-26 is a resin, you can remove it easily with a warm spreader or file if necessary. AH-26 does not break down easily. If contained in the canal, it will remain indefinitely. AH-26 is an excellent sealant, as proved by the many methylene blue studies. Endodontics for GP: Would you ever fill a canal with AH-26 without using gutta-percha? Abou-Rass: No, I do not recommend eliminating the gutta-percha to use the sealer alone because you will not be able to achieve a solid fill. You will end up with air pockets or voids if you do not use gutta-percha. Also, I would be concerned about control if you use any type of syringe to place the sealer. Lack of control has always been my major objection to paste fillers. . . . If the day comes that we can fill the canal solidly in three dimensions with sealer alone, then I will gladly convert to this technique. Endodontics for GP: How do you remove AH-26 if retreatment of the canal becomes necessary? Abou-Rass: Because it is an epoxy resin, AH-26 is easy to remove by softening it with heat. Endodontics for GP: What are the main indications for

using AH-26? Abou-Rass: I use AH-26 in all cases, but especially in cases of resorption or any time there is a possibility of an overfill. Dalat DM, Önal B. Apical Leakage of a New Glass Ionomer Root Canal Sealer. J Endodon 1998;24(3):161-163. A new glass ionomer root canal sealer (KetacEndo) has been developed. The purpose of this study was to compare the apical leakage of Ketac-Endo and AH26 using two different filling techniques and a controlled vacuum procedure. Sixty-four extracted human maxillary anterior teeth were instrumented and divided into four groups of 15 roots each. The groups were obturated as follows: group 1, single cone technique and Ketac-Endo; group 2, a lateral condensation technique and Ketac-Endo; group 3, a single cone technique and AH26 (this technique and cement is similar to that of the EZ-Fill system) ; and group 4, a lateral condensation technique and AH26. After storage in 100% humidity at 37ºC for 1 week, the root surfaces were coated with two layer of nail polish and sticky wax. All specimens were immersed in a vacuum flask containing 2% methylene blue dye solution. The air was evacuated with a vacuum pump. The roots were sectioned longitudinally, and the linear extent of dye penetration was measured. Statistical analysis revealed that there were no significant differences between any of the groups (1-4). Musikant BL, Cohen BI, Deutsch, AS. Simplifying Obturation. Dent Today 1998;17(5):134-135. Discussed in this paper were the numerous disadvantages of warm gutta percha techniques; 1. A lack of an adequate cement interface, 2. Shrinkage of the gutta percha upon cooling, 3. The compensating pressure techniques to reduce the effects of shrinkage add complexity, 4. All thermoplastic techniques are relatively expensive with respect to equipment and materials, 6. Some thermoplastic techniques have a solid inner core that is difficult to remove in post hole fabrication. The development of the patented EZ-Fill bi-directional spiral and epoxy root canal cement offers the dentist an innovative way to control and direct the flow of an endodontic sealer (EZ-Fill epoxy-resin root canal cement) effectively coating the canal walls and any accessory invaginations that might exist. Combining effective canal coating with a well fitted medium-fine or medium gutta percha point, itself coated the most


apical 4 mms, seals the canal at least as effectively as lateral condensation and thermoplastic techniques. Musikant BL, Cohen BI, Pagnillo MK, Deutsch, AS. Apical Leakage of Three Endodontic Fill Systems. J Dent Res 1998;77 (Abstract #2543):949. The purpose of this study was to evaluate the apical leakage of three endodontic procedures; lateral condensation, Thermafil (Tulsa), and a new EZ-Fill Bi-directional spiral system (Essential Dental Systems). This study consisted of 50 recently extracted single rooted human teeth divided into 5 groups with 10 specimen each. All groups, except for the negative control group, had the following initial procedure performed. An access opening to the pulp was obtained and the canals were irrigated with a 5.25% sodium hypochlorite solution. For Group 1 (Lateral Condensation) epoxy cement was placed on the master point which was used to coat the canal. More cement was placed on the master point and then the point was fully seated. For Group 2 (No-Treatment, negative control) no instrumentation or obturation was performed. Group 3 (Instrumented but not obturated, positive control) no further treatment was performed. Group 4 (EZ-Fill Bi-directional spiral system, was performed according to manufacturer’s instructions) a master gutta percha point was fitted to the apex and EZ-Fill epoxy cement was applied to the canal using EZ-Fill Bi-directional spiral in a slow speed handpiece. The master point was coated with EZ-Fill epoxy cement and fully seated in the canal. Group 5 (Thermafil obturation, was performed according to manufacturer’s instructions) the master point was heated in a Tulsa oven for 7 minutes and the Thermafil obturator was fully seated in the canal. All roots were then painted with 3 coats of nail enamel, except for 2 mm at the apical end. The test specimens were suspended with the apical ends in a 2% methylene blue solution (pH of 3.14) for two weeks. The teeth were removed and excess dye was washed off then sectioned buccolingual with a shape knife. The percentage of leakage was calculated by measuring the length of dye penetration divided by the total length of the canal. A Kruskal-Wallis non-parametric test followed by a Bonferroni-adjusted multiple pairwise Mann-Whitney test was used to compare leakage percentages across the five groups and was considered significant if p<0.005. The results showed the EZ-Fill Bi-directional spiral system had less apical leakage (1.8% ±1.59) than Thermafil (3.59% ±5.90) and Lateral Condensation (4.30% ±5.56). Both positive and negative controls had mean percent apical leakage of 100%. Statistical results showed that Lateral Condensation, Thermafil, and EZ-Fill Bi-directional system did not differ from each other but differed from the No Treatment group (negative control) and the Instrument-Unfilled group (positive control). In this study, the EZ-Fill Bi-directional spiral system produced a tighter apical seal

than either lateral condensation or Thermafil techniques, but was not significantly different from the other fill techniques. EZ-Fill Bi-directional spiral system is a good alternative to lateral condensation and Thermafil obturation. Cohen BI, Pagnillo MK, Musikant BL, Deutsch, AS Evaluation of the release of formaldehyde for three endodontic filling materials. Oral Health 1998;88(12):37-39. The purpose of this study was to measure the amount of formaldehyde released from three types of endodontic sealing cement (AH-Plus, EZ-Fill, and AH-26). Formaldehyde release was analyzed using High Performance Liquid Chromatography, which could detect as low as 0.25 ppm. The data was tabulated after two runs. The two paste system of AH-Plus endodontic sealing cement had the least amount of formaldehyde release (0.00039%, 3.9 ppm). This was followed by EZ-Fill (0.054%, 540 ppm) endodontic cement and AH-26 (0.1347%, 1347 ppm) endodontic cement which yielded the greatest formaldehyde release. Both of these cements (EZ-Fill and AH-26 endodontic filling cements) are base on a powder-liquid mix. The relatively minute amounts of formaldehyde released by the cement studied, especially AH-Plus and EZ-Fill endodontic cement warrants their continuous use as endodontic sealing cements. The clinician who wants to be able to control the flow of an endodontic cement and lower their contact of formaldehyde release can use EZ-Fill endodontic sealing cement as an alternative. Musikant BL, Cohen BI, Deutsch AS. Simplified Obturation of Tapered Canal PreparationsCompendium 1998;19(11):1152-1155. The development of the EZ-Fill bi-directional spiral offers the dentist an innovative way to control and direct the flow of an endodontic sealer (EZ-Fill epoxy-resin cement) effectively coating the canal walls and any accessory invaginations that might exist. Combining effective canal coating with a well fitted medium-fine or medium gutta percha point, itself coated the most apical 4 mms, seals the canal at least as effectively as lateral condensation and thermoplastic techniques. The EZ-Fill System represents an example of cognitive dissonance to some degree. In recent years, those most committed to thermoplastic techniques have invested heavily in time and effort to achieve a skill not easily acquired. They have done so, because they believe thermoplastic techniques when done right obturate the canal better than other techniques. They couple


wider tapered instrumentation to the thermoplastic technique alone. A review of the literature offers a variety of conflicting results with the majority of studies saying they are all equivalent. The ability of a bi-directional spiral (EZ-Fill) controlling and directing the flow of cement coupled to a well fitting single tapered point obturating a canal space as well as a thermoplastic technique potentially undermines the effort that was made to attain thermoplastic skills. Musikant BL, Cohen BI, Deutsch AS. Rethinking Endodontics: Attaining Total Obturation of the Root Canal System With a Simplified System. AGD (General Dentistry) Jan/Feb 1999;47(1):73-82. A sequence of steps constituting an innovative way of cleansing, shaping and obturation a root canal system is described. The advantages of this sequence over other instrumentation and obturation techniques are discussed. The advantages of the EZ-Fill obturation technique over other obturation techniques: A. Placement of a substantial gutta percha point (either fine medium or medium) that predictably binds at the apex. B. A reliance on the plasticity of the high silver epoxy-resin (EZ-Fill) (approximately 2 times as radiopaque as AH-26, an epoxy-resin cement available in the U.S. market since 1957) to seal the interface between the master gutta percha point and the walls of the canal as well as all accessory invaginations, doing away with: 1. Thermoplasticizing gutta percha with its subsequent shrinkage coupled to a less than reliable cement interface (maximum 62.5% coverage). 2. The stress induced in the root from vertical and lateral condensation. 3. The overfills associated with traditional vertical and lateral condensation. 4. The inflammation associated with excess eugenol based cements impinging on intact periodontal ligament spaces. C. Neither the master gutta percha point nor the EZ-Fill cement shrinks during polymerization. In fact, as the room temperature gutta percha warms to body temperature a slight expansion of approximately 2% takes place, producing no stress on a cement interface which sets in 24 hours. D. Minimum time is needed to obturate with the EZ-Fill technique after proper shaping. E. The EZ-Fill technique eliminates the need for expensive armamentarium associated with thermoplastic placement of gutta percha. F. Dye studies demonstrate that the EZ-Fill technique is at least the equal in sealing ability when compared to lateral and vertical condensation and thermoplastic techniques. G. Previous studies of a similar epoxy-resin demonstrate its superior performance in reducing leakage, maintaining its integrity over many years and being non-toxic and non-

inflammatory binding physically and chemically to the dentin and gutta percha point. Cohen BI, Pagnillo MK, Musikant BL, and Deutsch AS. An In Vitro Study of the Cytotoxicity of Two Root Canal Sealers. J Endodon 2000;26(4):228-229. The purpose of this in vitro study was to determine the cytotoxicity of two epoxy root canal sealing materials (AH-26 and AH-Plus, L.D. Caulk). AH-26 and AH-Plus endodontic filling cements consists of a powder and liquid component and a paste/paste component. AH-Plus is a new endodontic filling material in which little research is found in the literature. This agar diffusion cytotoxicity test was conducted based on the procedures described in the International Organization for Standardization (ISO 1993). The biological reactivity of a mammalian monolayer, L929 mouse fibroblast cells, in response to the test article was determined. The AH-26 and AH-Plus root sealing cements were mixed according to manufacturer’s instructions. For AH-26 root sealer, two round piles of AH-26 powder was mixed with one drop of AH-26 liquid. For AH-Plus root sealer, Paste A and Paste B were mixed together in a 1:1 ratio until they were homogenous. The test article was applied to a sterile filter disc (100 mm2) which was placed directly on the agar surface with the test article in contact with the agar surface. The positive control article (natural rubber) and the negative control articles (silicone) were used to verify proper functioning to the test system. All treatments were prepared in triplicate and were incubated at 37 ±1 °C, in a humidified atmosphere containing 5 ±1% carbon dioxide, for 48 hours. Biological reactivity was rated on a scale from Grade 0 (no reactivity) to Grade 4 (Severe reactivity). After 48 hours the positive control article exhibited Moderate reactivity (Grade 3) and the negative control article exhibited no signs of reactivity (Grade 0). The test articles AH-26 and AH-Plus root canal sealing cement are considered cytotoxic and exhibited a rating of Grade 4 (severe reactivity). Similar cytotoxicity results have been found in literature for AH-26 and other root canal sealing cements. From the data obtained from this study the following conclusion were made; after 48 hours, both AH-26 and AH-Plus root canal sealing cements exhibited severe reactivity (Grade 4). The test articles of AH-26 and AH-Plus root canal sealing cements are consider cytotoxic and do not meet the requirements for the agar diffusion test according to the ISO 1993 test specifications.


Musikant BL, Cohen BI, Pagnillo MK, Deutsch AS. Formaldehyde Release from Three Endodontic Filling Cements. J Dent Research. (IADR Abstract #1707) 1999;78 :319. The purpose of this in vitro study was to measure the amount of formaldehyde (CH2O) released from three types of endodontic sealing cement (AH-Plus, EZ-Fill, and AH-26). AH-Plus is a paste/paste system and is claimed to be a formaldehyde free material, while AH-26 and EZ-Fill are powder/liquid systems which are epoxy based endodontic sealers. The cement systems were mixed according to manufacturer’s instructions to obtain a total mass of 5 grams that was required for High Performance Liquid Chromatography (HPLC) analysis. The sample was mixed with a stainless steel spatula until homogeneous and was allowed to cure for 60 minutes. The mixtures were weighted into an Erlenmeyer flask and 100 mL of distilled waster was added to the flask. A buffer was added to adjusted the pH to 5. Next 2,4-dinitrophenylhydrazine (DNPH) reagent was added to the flask then placed in a 40°C water bath for 60 minutes. The resulting extract was filtered and transferred to Kudema-Danish tubes to evaporate the dichloromethane (CH2Cl2) solution. The solution was reduced to approximately 4 mL. This solution was transferred to a 10 mL volumetric flask. The final solution was analyzed by High Performance Liquid Chromatography (HPLC) that had the ability to detect as low as 0.25 ppm in concentration. The system parameters were as follows: Column, 250 mm x 4.6 mm ODS; Mobile Phase, 70% acetonitrile-to-30% water; Flow Rate, 1.0 mL/minute; Detection, UV @ 360 nm; Retention Time; 5.8 minutes. The data was tabulated after two runs. The release of formaldehyde obtained by the HPLC analysis showed that AH-26 endodontic cement had the highest release 0.1347% of it mass (1347 ppm). This was followed by EZ-Fill endodontic filling cement, 0.054% of its mass (540 ppm) and AH-Plus endodontic sealing cement, 0.00039% (3.9 ppm) formaldehyde release. From the data obtained it was concluded that the use of EZ-Fill and AH-Plus endodontic cements yielded relatively low amounts of formaldehyde. It can also be concluded that a clinician who wants the ability to control the viscosity of the endodontic sealing cement and lower formaldehyde concentration can use EZ-Fill endodontic cement as a viable alternative. The Cytotoxicity of resin-based root canal sealers. Huang TH, Kao CT, LII H and Chou MY. J Dent Res (IADR Abstract #1320) 1999;78 :270. The AH-26 and AH plus root canal sealers are resin based sealers. The difference between the two sealers was that AH-26 sealers releases formaldehyde after mixing, but not

the AH plus sealer (information provided by the manufacture). The purpose of this study was to evaluate the cytotoxicity of AH-26 and AH plus treated on the primary cultured human gingival fibroblasts. The sealers were mixed according to the manufacture's instructions. The final concentration of AH-26 and AH plus sealers were as follows: 0.01, 0.02, 0.04, 0.08 and 0.1 (µg/µl). The sealer were evaluated using the3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium Bromide-Formazan (MTT) calorimetric assay on the primary cultured of human gingival fibroblasts. Results were analyzed by ANOVA and the Student-Newman-Keul tests with the value of statistical significance being set at p<0.05. The 50% inhibition concentration (IC50) was also calculated. The Sealers showed cytotoxicity by MTT assay in concentration dependent manner (p<0.05). The AH plus sealer has higher IC50 than the AH 26 sealer (p<0.05). Hence, they conclude that both the AH-26 and AH plus sealers are toxic to the primary cultured human gingival fibroblasts. The cytotoxicity of the AH plus sealer is stronger than the cytotoxicity of the AH-26 sealer. 1999 CRA Dental Product Buying Guide.CRA-Clinical Research Associates Newsletter. 1999;23(1):2. Products which were highly rated after clinical field trials: EZ-Fill Obturation System - Rated Good to Excellent Tech-Specs: The EZ-Fill System. Essential Dental Systems, Inc. Contemporary Esthetics 1999;3(5):94-95. This article reviews the EZ-Fill Obturation System, stating its easier, faster, and superior endodontic filling technique. Demonstrated is the ability of the EZ-Fill bi-directional spiral to control the flow of cement into the root canal, and lateral canals without cement going beyond the apex. Unlike thermoplastic gutta-percha techniques, there is no need for expensive gutta-percha points, and complicated techniques that require a good deal of practice to fit within a narrow window of success. Those who have used the EZ-Fill system state that they no longer have any anxiety during the obturation procedure, and in fact, point with pride to how they can fill even the most complex canal systems in a thorough and predictable manner.


The Single Point Technique: A Most Efficient Alternative For Endodontic Obturation. Musikant, BL, Cohen BI, Deutsch AS. GP: J of the NYS AGD. 1999;March:10-12. An uncompromising standard for endodontic obturation has always been the intimate fit of the gutta percha to the walls of the root canal. Whether the obturation techniques involve lateral and vertical condensation or thermoplasticizing, the proximity of the gutta percha to the walls of the prepared canal has always been considered essential in establishing a thin cement interface between the gutta percha and the dentin, a necessary requirement for an optimum seal. A thin cement interface has traditionally been a requirement because most root canal sealers have weak matrices when set and are subject to rapid degradation when subjected to the oral fluids. The thinner the interface, the less likely that dissolving oral fluids will react with the cement especially given the hydrophobic nature of gutta percha. The innovation of one instrument, the EZ-Fill bi-directional spiral, has given the dentist control over the flow and direction of the root canal cement. By controlling the flow of a sealer with a matrix stronger than that of gutta percha, EZ-Fill epoxy-resin cement, the unnecessary complications introduced by lateral condensation and thermoplasticization are eliminated allowing the dentist to obturate quickly, thoroughly and easily with a much larger and more easily attained window of success. Technique Update: Improving on the Lentulo Spiral. Arzt AH. American Endodon Society. 1999;87:5. The EZ-Fill spiral is described as a bi-directional instrument that produces a coronal and apical cement flow simultaneously. When these opposite flows of cement meet, they are forced to travel laterally thoroughly coating the walls and any lateral canals that may exist. Since the apical end of the spiral forces the cement coronally, cement does not travel beyond the apex and become an overfill. In practical use, the above description actually works in this manner. Radiographs taken after completion of the canals, revealed a solid fill to the apex. EZ-Fill Obturation System Lives Up To Its Name! Weathers K. Practical Endodontics 1999;8(5)33-35. The author conculdes: The EZ-Fill system produces far less post-op pain as compared to symptoms associated with ThermaSeal, which is part of the Thermafill system. It is believed that post-op pain associated with Thermfill comes from hydraulically forcing sealer beyond the apex, as the obturator is rapidly plunged into the root canal. In contrast, the gutta -percha point is gently and slowly introduced into the EZ-Fill cement, which allows the excess to escape coronally around the point. Dr. Weathers states: With the

EZ-Fill system, he is now getting the best-looking final fills he has ever seen, and is currently teaching the EZ-Fill technique as part of his Endodontic Seminar. Seidman D. A General Dentist’s Viewpoint of Two New Endodontic Techniques. Compendium 1999:20(10):921-934. Over 3 years ago, two new endodontic techniques were developed. The first was a straightforward, comprehensive approach for root canal instrumentation. The second was a simple and predictable obturation system, EZ-Fill. The combination of these systems lead impressive results that were easily attained. The instrumentation method uses existing armamentarium, allowing nearly any canal to be shaped to ideal form to precisely match a tapered gutta percha point. The root canal sealer technique incorporates controlled placement of an EZ-Fill epoxy-resin cement that allows for a thoroughly sealed, single-cone root canal fill. The results rival other available systems. This article presents a stepwise guide to achieve stress-free, successful case results that general dentists and endodontists desire. Musikant BL, Cohen BI, Deutsch AS. Report of a Simplified Endodontic Technique. Compendium 1999:20(11):1088-1094. Using a simplified step-back sequence, which consists of traditional .02 tapered stainless-steel hand reamers, the No 2 peeso reamer, and four manual nickel-titanium instruments, a dentist can easily, safely, and economically create a continuously tapered canal shape. This article discusses the complete coating of canal walls with EZ-Fill epoxy-resin cement, which is delivered with a bi-directional spiral; and total obturation with a single gutta percha point, which is matched closely to the tapered shape. The results of this system are compared with other techniques. Cohen BI, Pagnillo MK, Musikant BL, and Deutsch AS. In Vitro Study of the Cytotoxicity for Two Root Canal Sealers. J Dent Res 2000;79:549 (Abstract 3247). The purpose of this in vitro study was to determine the cytotoxicity of two epoxy root canal sealing materials (AH-26 and AH-Plus, L.D. Caulk). AH-26 and AH-Plus endodontic filling cements consists of a powder and liquid component and a paste/paste component. AH-Plus is a new endodontic filling material in which little research is found in the


literature. This agar diffusion cytotoxicity test was conducted based on the procedures described in the International Organization for Standardization (ISO 1993). The biological reactivity of a mammalian monolayer, L929 mouse fibroblast cells, in response to the test article was determined. The AH-26 and AH-Plus root sealing cements were mixed according to manufacturer’s instructions. For AH-26 root sealer, two round piles of AH-26 powder was mixed with one drop of AH-26 liquid. For AH-Plus root sealer, Paste A and Paste B were mixed together in a 1:1 ratio until they were homogenous. The test article was applied to a sterile filter disc (100 mm2) which was placed directly on the agar surface with the test article in contact with the agar surface. The positive control article (natural rubber) and the negative control articles (silicone) were used to verify proper functioning to the test system. All treatments were prepared in triplicate and were incubated at 37 ±1 °C, in a humidified atmosphere containing 5 ±1% carbon dioxide, for 48 hours. Biological reactivity was rated on a scale from Grade 0 (no reactivity) to Grade 4 (Severe reactivity). After 48 hours the positive control article exhibited Moderate reactivity (Grade 3) and the negative control article exhibited no signs of reactivity (Grade 0). The test articles AH-26 and AH-Plus root canal sealing cement are considered cytotoxic and exhibited a rating of Grade 4 (severe reactivity). Similar cytotoxicity results have been found in literature for AH-26 and other root canal sealing cements. From the data obtained from this study the following conclusion were made; after 48 hours, both AH-26 and AH-Plus root canal sealing cements exhibited severe reactivity (Grade 4). The test articles of AH-26 and AH-Plus root canal sealing cements are consider cytotoxic and do not meet the requirements for the agar diffusion test according to the ISO 1993 test specifications. Musikant BL, Cohen BI, Deutsch AS. Traditional, modern and post modern endodontics: part one. Endodontic Practice 2000;Jan:18-26. The first of two articles charting the recent history of endodontic development over the last 30 years. It outlines traditional endodontic techniques, to the development of newer “modern” methods which, in turn, have led to “post modern” techniques eliminating problems derived from the recent developments. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. The Effects of Eugenol and Epoxy-resin on the strength of a hybrid composite resin. AGD (Gen Dent) Submitted 2000. The compatibility of the chemistries regarding different dental materials (root canal sealer and composite core build-up restoratives) is an important factor for a

successful restoration. However, there are limited studies in the literature demonstrating eugenol’s effect on the gross physical characteristics (compressive and diametral tensile strength) for a classical hybrid composite resin. No studies are known in the literature regarding the interaction of epoxy-resin based root canal sealers with composite resins. The aim of this in vitro study was to determine the effects on compressive and diametral tensile strength for a classical chemical cure composite resin (Henry Schein Composite Anterior-Posterior dental restorative, Port Washington, NY) when in contact with either; eugenol or an epoxy-resin in a variety of situations: 1) added during mixing of a composite resin before curing, 2) vapor exposure to cured samples and 3) specimens placed directly (after curing). The experiment was divided into two parts; part one, compressive strengths (CS) and in part two diametral tensile (DT) strength. This experiment was divided into seven groups with 10 specimens per group. In groups 1-3, specimens were affected by Eugenol U.S.P. (Roth International, Chicago, Ill) ; specimens of groups 4-6 were affected by EZ-Fill (Essential Dental Systems, S, Hackensack, NJ) ; and the seventh group served as a control group. The CS and DT were evaluated on a 810 MTS universal testing machine with a cross-head speed of 0.25 inches per minute (0.635 cm/min). Results were CS (psi), DT(psi); group 1 CS 0, DT 0; group 2 CS 29050 + 5413, DT 4063 + 465; group 3 CS 27951 + 3302, DT 4401 + 820; group 4 CS 25353 + 2490, DT 4052 + 496; group 5 CS 28441 + 5736, DT 3897 + 597; group 6 CS 27504 + 4272, DT 4146 + 449; group 7 (control) CS 26466 + 2853, DT 4218 + 549. One-way ANOVA analysis was performed on groups 2 through 7 and a result was statistically significant if P < 0.05. Only the addition of eugenol during mixing with the composite resin (directly before curing) resulted in specimens that did not achieve a full cure (0 psi). There were no significant differences among the groups (2 through 7) with respect to either CS (P = 0.17) and DT (P = 0.39). Group 1 (mixed directly with eugenol) was found to be statistically different from groups 2 through 7. In conclusion, eugenol dramatically affects the strength of a composite resin during mixing where EZ-Fill’s epoxy-resin does not. All other groups where cured samples were measured resulted in strengths similar to that of the control.


Deutsch AS, Cohen BI, Musikant BL, Kase D. A Study of One Visit Treatment Using EZ-Fill Root Canal Sealer. Practical Endodontics June 2001;4(3):29-36. The purpose of this retrospective clinical study was to determine outcome (success or non-success) following endodontic treatment using EZ-Fill (Essential Dental Systems, Inc S. Hackensack, NJ) epoxy root canal sealer with the bi-directional spiral obturation system. The endodontically treated canals were obturated with EZ-Fill bi-directional spiral and epoxy resin sealer, which is an AH-26 epoxy derivative. A sample size of 153 endodontically treated teeth for 145 patients was preformed by three endodontic practitioners during the period from 1/1/97 to 12/31/97 (two year recall study). The mean age of the patients were 53 ranging from 20 to 85 (with 61% female and 39% male). There was a recall rate of 42%. The following patient factors were collected; age, sex, number of patient visits, vitality (or non-vitality, whether there was PAR (periapical area of radiolucency)) and radiographic findings. The fisher exact test was used to determine outcome success or non-success with association of sex, number of visits and vitality (or non-vitality). Success was defined as; 1) on radiograph a preexisting lesion had gotten smaller or healed completely, 2) on radiograph no new lesion had formed where there was no lesion before, 3) the patient upon questioning at the recall examination was asymptomatic, and 4) the patient was functioning well with the endodontically treated tooth. The success rate was 94.1% (144 successful endodontic treatments with 9 unsuccessful). There was no significant association between success rate (p = 0.442), sex (p = 0.707), number of visits (p = 0.442), vitality (p =0.757). This study compares well with literature success rates which range from 78% to 95%. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Shear bond strength for four endodontic sealers. Endodontic Practice 2002;5(June):9-14. The most important feature of a root canal sealing material is bond strength to dentin. However, there are no studies analyzing the relationship between bond strength of a sealer and their chemical nature. This study tested the dentinal bond strength under shear conditions for four endodontic root canal sealers. The experiment was divided into 4 groups with 10 specimens per group. The shear bond strengths were evaluated on a 810 MTS universal testing machine with a crosshead speed of 6.35 mm/minute. The shear bond strength values (psi) were: EZ-Fill 323.9 +63.9, AH-Plus 252.9 +59.3 with RSA RoekoSeal Automix and Roth zinc oxide/eugenol formulation having no bond strength to dentin (0 psi). A non-parametric Kruskal-Wallis (KW) test was performed and there was a statistical significance difference between EZ-Fill and AH-Plus (P <

0.0196). Both EZ-Fill and AH-Plus were statistically greater than RSA RoekoSeal Automix and Roth zinc oxide/eugenol formulation (P < 0.0001). The chemistry of the final polymer matrix for a root canal sealer plays a large roll with regards to dentin bonding. The epoxy-resin chemistry has superior bond strength to dentin compared to the chemistries of dimethylsiloxane and zinc oxide/eugenol. Musikant BL, Cohen BI, Deutsch AS. Traditional, modern and post modern endodontics: part two. Endodontic Practice 2000;March:6-17. The second of two articles charting the recent history of endodontic development over the last 30 years. It outlines traditional endodontic techniques, to the development of newer “modern” methods which, in turn, have led to “post modern” techniques eliminating problems derived from the recent developments. The “post modern” techniques demonstrate the safe, predictable obturation with the patented EZ-Fill bi-directional spiral and epoxy root canal cement system. Musikant BL, Cohen BI, Volovich Y, Deutsch AS. Strength Effects for Composite when in Contact with Eugenol Vs. Epoxy-resin. J Dent Res (Abstract 1480) 2001;80:711. The compatibility of the chemistries regarding different dental materials (root canal sealer and composite core build-up restoratives) is an important factor for a successful restoration. However, there are limited studies in the literature demonstrating eugenol’s effect on the gross physical characteristics (compressive and diametral tensile strength) for a classical hybrid composite resin. No studies are known in the literature regarding the interaction of epoxy-resin based root canal sealers with composite resins. The aim of this in vitro study was to determine the effects on compressive and diametral tensile strength for a classical chemical cure composite resin (Henry Schein Composite Anterior-Posterior dental restorative, Port Washington, NY) when in contact with either; eugenol or an epoxy-resin in a variety of situations: 1) added during mixing of a composite resin before curing, 2) vapor exposure to cured samples and 3) specimens placed directly (after curing). The experiment was divided into two parts; part one, compressive strengths (CS) and in part two diametral tensile (DT) strength. This experiment was divided into seven groups with 10 specimens per group. In groups 1-3, specimens were affected by Eugenol U.S.P. (Roth International, Chicago, Ill) ; specimens of groups 4-6 were affected by EZ-Fill


(Essential Dental Systems, S, Hackensack, NJ) ; and the seventh group served as a control group. The CS and DT were evaluated on a 810 MTS universal testing machine with a cross-head speed of 0.25 inches per minute (0.635 cm/min). Results were CS (psi), DT(psi); group 1 CS 0, DT 0; group 2 CS 29050 + 5413, DT 4063 + 465; group 3 CS 27951 + 3302, DT 4401 + 820; group 4 CS 25353 + 2490, DT 4052 + 496; group 5 CS 28441 + 5736, DT 3897 + 597; group 6 CS 27504 + 4272, DT 4146 + 449; group 7 (control) CS 26466 + 2853, DT 4218 + 549. One-way ANOVA analysis was performed on groups 2 through 7 and a result was statistically significant if P < 0.05. Only the addition of eugenol during mixing with the composite resin (directly before curing) resulted in specimens that did not achieve a full cure (0 psi). There were no significant differences among the groups (2 through 7) with respect to either CS (P = 0.17) and DT (P = 0.39). Group 1 (mixed directly with eugenol) was found to be statistically different from groups 2 through 7. In conclusion, eugenol dramatically affects the strength of a composite resin during mixing where EZ-Fill’s epoxy-resin does not. All other groups where cured samples were measured resulted in strengths similar to that of the control. Wu MK, Ozok AR, Wesselink PR. Sealer distribution in root canals obturated by three techniques. Int Endodon Journal 2000;33:340-345. The aim of this study was to observe sealer distribution in root canals filled by different root filling techniques. AH26 (0.05mL) dyed with carbon black powder was placed into the prepared root canals of maxillary central incisors using a lentulo spiral. Thereafter the canals were obturated using three different gutta-percha root-filling techniques. Horizontal sections were cut in the apical and middle portions of the filled canals. Images of the cross sections were scanned and the percentage of sealer coated canal perimeter (PSCP) was measured using a computer digital imaging system. At both 3mm and 6mm from the apex the PSCP was significantly higher after single cone (no condensation) than after vertical or lateral condensation (P<0.0001). Please Note: The EZ-Fill obturation technique employs the use of a single cone technique with the patented EZ-Fill bi-directional spiral and epoxy root canal cement (an AH26 derivative). Deutsch AS, Cohen BI, Musikant BL, Kase D. Two Year Recall Study for EZ-Fill Root Canal Obturation System. J Den Res (Abstract 1773), 2001;80:257. The purpose of this retrospective clinical study was to determine outcome (success or non-success) following endodontic treatment using EZ-Fill (Essential Dental Systems, Inc S. Hackensack, NJ) epoxy root canal sealer with the bi-directional spiral obturation system. The

endodontically treated canals were obturated with EZ-Fill bi-directional spiral and epoxy resin sealer, which is an AH-26 epoxy derivative. A sample size of 153 endodontically treated teeth for 145 patients was preformed by three endodontic practitioners during the period from 1/1/97 to 12/31/97 (two year recall study). The mean age of the patients were 53 ranging from 20 to 85 (with 61% female and 39% male). There was a recall rate of 42%. The following patient factors were collected; age, sex, number of patient visits, vitality (or non-vitality, whether there was PAR (periapical area of radiolucency)) and radiographic findings. The fisher exact test was used to determine outcome success or non-success with association of sex, number of visits and vitality (or non-vitality). Success was defined as; 1) on radiograph a preexisting lesion had gotten smaller or healed completely, 2) on radiograph no new lesion had formed where there was no lesion before, 3) the patient upon questioning at the recall examination was asymptomatic, and 4) the patient was functioning well with the endodontically treated tooth. The success rate was 94.1% (144 successful endodontic treatments with 9 unsuccessful). There was no significant association between success rate (p = 0.442), sex (p = 0.707), number of visits (p = 0.442), vitality (p =0.757). This study compares well with literature success rates which range from 78% to 95%. Musikant BL, Cohen BI, Deutsch AS. The Evolution of Instrumentation and Obturation Leading to a Simplified Approach. Compendium 2000;21(11):980-990. The evolution of endodontic treatments has included the introduction of rotary crown-down nickel-titanium instrumentation and the use of thermoplasticized gutta percha to obturate canals. Although these techniques have provided dentists with solutions to problems encountered with earlier generation endodontic procedures, they have also presented deficiencies that are now receiving some critical review. As a result, a systematic technique has been developed that provides a simplified approach for root canal instrumentation and predictable obturation. This article reviews the aspects of earlier endodontic techniques and provides the step-by-step clinical protocol involved the use of the patented EZ-Fill bi-directional spiral and epoxy -resin root canal cement system.


Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Comparison of Shear Bond Strengths for four Endodontic Sealers. J Dent Res (Abstract 1310) 2001;80:690. The most important feature of a root canal sealing material is its chemical bond strength to dentin. However, there are no studies analyzing the relationship between bond strength of a sealer and their chemical nature. This in vitro study tested the dentinal bond strength under shear conditions for four endodontic root canal sealers {AH-Plus (Dentsply, Ltd), EZ-Fill (Essential Dental Systems, Inc), RSA RoekoSeal Automix (Roeko Langenau) and Roth’s zinc oxide/eugenol formulation (Roth International, Ltd). Both EZ-Fill and AH-Plus are epoxy-resin based sealers where RSA RoekoSeal Automix is polydimethylsiloxane based. The experiment was divided into 4 groups with 10 specimens per group. The shear bond strengths were evaluated on a 810 MTS universal testing machine with a crosshead speed of 6.35 mm/minute. The shear bond strength values (psi) were: EZ-Fill 323.9 +63.9, AH-Plus 252.9 +59.3 with RSA RoekoSeal Automix and Roth zinc oxide/eugenol formulation having no bond strength to dentin (0 psi). A non-parametric Kruskal-Wallis (KW) test and multiple pairwise Mann-Whitney (MW) tests were performed (a statistically significant result occurred when P < 0.05) and there was a statistical significant difference between EZ-Fill and AH-Plus (P < 0.0196). Both EZ-Fill and AH-Plus were statistically greater than RSA RoekoSeal Automix and Roth zinc oxide/eugenol formulation (P < 0.0001). The epoxy-resin based sealers EZ-Fill and AH-Plus has superior bond strengths to dentin compared to RSA RoekoSeal Automix and Roth zinc oxide/eugenol formulation. The chemistry of the final polymer matrix for a root canal sealer plays a large roll with regards to dentin bonding. The epoxy-resin chemistry has superior bond strength to dentin compared to the chemistries of dimethylsiloxane and zinc oxide/eugenol. Seidman D. Dwie nowemetody endodontyczne z punktu widzenia lekarza stomatologa specjalnosci ogólnej. Stomatologia Wspolczesna 2000;5(7):61-63. (Published in Polish: A General Dentist’s Viewpoint of Two New Endodontic Techniques) Over 3 years ago, two new endodontic techniques were developed. The first was a straightforward, comprehensive approach for root canal instrumentation. The second was a simple and predictable obturation system, EZ-Fill. The combination of these systems lead impressive results that were easily attained. The instrumentation method uses existing armamentarium, allowing nearly any canal to be shaped to ideal form to precisely match a tapered gutta percha point. The root canal sealer technique incorporates controlled placement of an EZ-Fill epoxy-resin cement that allows for a thoroughly

sealed, single-cone root canal fill. The results rival other available systems. This article presents a stepwise guide to achieve stress-free, successful case results that general dentists and endodontists desire. Ham K, Trasatti C, Gutmann J. Comparison of sealer radiopacity by measuring optical density. J Endodont (Abstract 52) 2000;26(9):565. Additives to root canal sealers, such as barium sulfate or silver, enhanced the radiographic appearance of root canal obturation. The purpose of this study was to measure and compare the radiodensities of several sealers. Seven sealers were mixed according to manufacturers’ instructions and allowed to set in uniform thickness. Specimens were radiographed along with an aluminum stepwedge on No. 4 dental film at 70 kVp for 2.5 seconds with a source-object distance of 43.4 cm. The optical density at the center of each of the specimens was measured three times and the mean for each sample was calculated. The results were recorded and ranked radiopacity where the smallest number for optical density had the greatest radiopacity: Control (no exposure, 0.23), EZ-Fill Epoxy Root Canal Cement (0.79), AH Plus (0.80), Kerr’s-EWT (0.89), Tubliseal (1.05), Roth’s (1.08), Sealapex (1.19), and Wach’s (1.48). EZ-Fill recorded the highest radiopacity in this study. Millstein PL, Al-Khalidi A, Meyerowitz J. Determining resin cement post retention with eugenol/non-eugenol sealer. J Dent Res (Abstract 0199) 2001;80:551. Resin cements are used to cement metal and non-metal posts in endodontically treated teeth. This study evaluated post retention in teeth sealed with eugenol (Roth) and non-eugenol (AH26, Dentsply) based sealers. Sixty Group I maxillary anterior teeth were endodontically treated and filled with gutta percha and eugenol (Roth) and sixty Group II with a non-eugenol (AH26, Dentsply) based sealer. Crowns were removed and Parapost holes 1.6 mm wide (4.5) were prepared 10mm deep. Teeth were subdivided into groups according to post hole pretreatment: A. No pretreatment (control), B. Manually brushed posthole (PeesoBrush, Premier Dental), C. Manually brushed post hole with alcohol, D. Place alcohol on post hole walls with paper points. Posts were cemented with Panavia 21 (JMorita) according to directions, i.e.primer and cement. After 7 days in moist storage, teeth were grooved, mounted in resin in a Bencor ring (Danville Eng.) and tested using a Bencor Muti T system mounted on an Instron 4202 machine. Samples were tested in tension in a uniaxial


mode at 1mm/min. Peak loads were recorded in Newtons. An ANOVA was used with various t-tests to compare treatments to each other and to various individual treatments to each other and to various individual treatments. Post retention in canals pretreated prior to cementation were not statistically different. Mean post retention for AH26 was significantly higher (210±84N) than for Roth (144±64N). In this study, eugenol based sealer reduced resin post retention compared to the significantly higher retention for the epoxy-resom cement, AH26. EZ-Fill epoxy-resin root canal cement is an AH26 derivative. Musikant BL, Cohen BI, Deutsch AS. Alternatywna metodawypelniania kanalu korzeniowego: metoda pojedynczego cwieka. Stomatologia Wspolczesna 2001;8(1):49-52. (Paper published in Poland’s Stomatologia Wspolczesna (In Polish) The Single Point Technique: A Most Efficient Alternative For Endodontic Obturation.) An uncompromising standard for endodontic obturation has always been the intimate fit of the gutta percha to the walls of the root canal. Whether the obturation techniques involve lateral and vertical condensation or thermoplasticizing, the proximity of the gutta percha to the walls of the prepared canal has always been considered essential in establishing a thin cement interface between the gutta percha and the dentin, a necessary requirement for an optimum seal. A thin cement interface has traditionally been a requirement because most root canal sealers have weak matrices when set and are subject to rapid degradation when subjected to the oral fluids. The thinner the interface, the less likely that dissolving oral fluids will react with the cement especially given the hydrophobic nature of gutta percha. The innovation of one instrument, the EZ-Fill bi-directional spiral, has given the dentist control over the flow and direction of a root canal cement. Unlike the complications initiated by lateral condensation and thermoplasticized gutta-percha, the control of cement is accomplished by using the EZ-Fill bi-directional spiral and epoxy resin cement which results in a quick and though obturation procedure. Deutsch AS, Cohen BI, Musikant BL. A Primary Study on the Sealer Distribution in Canals Obturated with Three Different Endodontic Techniques. J Dent Res 82(Spec Iss A):970, 2003. The purpose of this in vitro study was to investigate the sealer distribution in teeth instrumented and obturated using three different clinical techniques. Four teeth in three different groups (EZ-Fill SafeSider/EZ-Fill, Lateral Condensation and Thermafil) were sliced in cross section, microscopically photographed and viewed on the

computer. All groups for all sections demonstrated similar morphological appearances. The apical 1mm section all groups demonstrated a central core filling material surrounded by sealer. The central core material (gutta percha or plastic carrier) did not directly or totally contact the canal wall. However, in all sections the sealer closely adapted to the dentinal canal wall. In all three clinical techniques (EZ-Fill SafeSider/EZ-Fill, Lateral Condensation and Thermafil) the endodontic sealer is responsible for the complete obturation and hermetic sealing of the canal. The EZ-Fill SafeSider/EZ-Fill technique demonstrated a more uniform and predictable gutta percha to cement morphology at all levels of the canal. Musikant BL, Cohen BI, Deutsch AS. Uproszczona metoda wypelniania zbieznych kanalów korzeniowych. Compendium Stomatolgii 2001;2:7-9. (Published in Polish: Simplified Obturation of Tapered Canal Preparations) The development of the EZ-Fill bi-directional spiral offers the dentist an innovative way to control and direct the flow of an endodontic sealer (EZ-Fill epoxy-resin cement) effectively coating the canal walls and any accessory invaginations that might exist. Combining effective canal coating with a well fitted medium-fine or medium gutta percha point, itself coated the most apical 4 mms, seals the canal at least as effectively as lateral condensation and thermoplastic techniques. The EZ-Fill System represents an example of cognitive dissonance to some degree. In recent years, those most committed to thermoplastic techniques have invested heavily in time and effort to achieve a skill not easily acquired. They have done so, because they believe thermoplastic techniques when done right obturate the canal better than other techniques. They couple wider tapered instrumentation to the thermoplastic technique alone. A review of the literature offers a variety of conflicting results with the majority of studies saying they are all equivalent. The ability of a bi-directional spiral (EZ-Fill) controlling and directing the flow of cement coupled to a well fitting single tapered point obturating a canal space as well as a thermoplastic technique potentially undermines the effort that was made to attain thermoplastic skills.


Musikant BL, Cohen BI, Deutsch AS. Uproszczona technika leczenia i wypelniania kanalów korzeniowych. Stomatologia Wspólczesna 2001;8(4):28-33. (Published in Polish: : Report of a Simplified Endodontic Technique) Using a simplified step-back sequence, which consists of traditional .02 tapered stainless-steel hand reamers, the No. 2 peeso reamer, and four manual nickel-titanium instruments, a dentist can easily, safely, and economically create a continuously tapered canal shape. This article discusses the complete coating of canal walls with EZ-Fill epoxy-resin cement, which is delivered with a bi-directional spiral; and total obturation with a single gutta percha point, which is matched closely to the tapered shape. The results of this system are compared with other techniques. Kato AS, Imura N, Gin-Ichiro H, Toda T. Effectiveness of EZ-Fill Instrumentation, Modified Balanced Force and GT-Profile .04 Rotary Instrumentation Techniques. J Endodont 2002;28(3)[abstract PR30]:261. Seventy-five mesial roots of human mandibular molars were used to compare canal transportation in the middle and apical segment of curved canals using EZ-Fill hand instrumentation, modified balance force concept and GT-Profile .04 rotary instrumentation techniques. The samples were divided into 3 groups of 25 roots each: Group A) EZ-Fill technique instrumentation, with manual and rotary instruments, Group B) Modified balance instrumentation, with gates glidden drills and manual instruments. Group C) GT-Profile instrumentation, with rotary instruments. The pre and post-instrumentation images and data were captured and stored for comparison using an image analyzer software connected to a stereomicroscope. In the middle segment all instrumentation techniques showed a tendency to cut more the distal side, without statistically significant difference. In the apical segment all instrumentation technique showed a centralized root canal preparation. Hata G, Imura N, Matsuda T, Kato A, Souza Filho FJ, Toda T. Apical Sealing Ability of the EZ-Fill Obturation Technique. J Endodont 2002;28(3)[abstract PR31]:261. The purpose of this study was to evaluate the apical sealing ability of the canals obturated with the EZ-Fill obturation technique. Eight-five extracted human permanent mandibular molars were used for this study. Following access cavity preparation, the distal root canal was instrumented up to #30 using GT-rotary Files according to the manufacturer’s instructions. Twenty-five teeth were obturated with the EZ-Fill obturation technique, 25 with

the System B technique, and 25 with conventional gutta-percha points and lateral condensation with sealer. The residual 10 teeth were used as negative and positive controls of 5 teeth each, respectively. Following obturation, all surfaces were covered with nail polish, except for the apical 2 mm. The teeth were immersed in India Ink for 5 days at 37°C. After removal of the ink, the teeth were rinsed in tap water and the nail polish was completely removed. Then, the teeth were demineralized and cleared in silicon oil. The greatest depth of linear penetration of the dye was measured to the nearest 0.001 mm using a Profile Projector. The average values of the measurements obtained by two evaluators were used to calculate the mean leakage and standard deviation for each experimental group. A one-way analysis of variance showed that there was no significant difference among the groups (p=0.289). Root canals obturated with the EZ-Fill technique showed the least dye penetration. Baumann MA, Loy R, Behrens O. Dye Penetration of Five Different Single Cone Techniques Compared to Lateral Condensation. J Dent Research 2002;81(Abstract 3474):A-428. The aim of this study was to compare various single cone techniques with cold or heated gutta percha and sealer. In 66 extracted incisors root canal treatment was performed and the teeth were divided into 6 groups for obturation. Methylene blue (0.2% was used to test for passive dye penetration). After clearing the teeth maximum dye penetration was measured under a stereomicroscope (x40) from two angles. Statistical analysis was done by means of ANOVA. The group obturated with the EZ-Fill bi-directional spiral showed superior sealing properties, significant difference (p<.001), to those groups of; Endomagic single cone .06 and sealer inserted with a lentulo No. 40. Tagger M, Tagger E, Tjan AHL, Bakland LK. Measurement of Adhesion of Endodontic Sealers to Dentin. J Endodont 2002;28(5):351-354. The bond strength of root canal sealers to dentin is an important property for maintaining the integrity of the seal of root-canal fillings. The implication of study verifies a previously reported study (Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Shear bond strength for four endodontic sealers. Endodontic Practice 2002;5(June):9-14.) in which the epoxy-resin based root canal cements provide the highest bond strength and zinc oxide/eugenol based cements


such as Roth zinc oxide/eugenol recorded no bond strength (0 psi). Musikant BL, Cohen BI, Deutsch AS. A Two and a Half Year Perspective of Simplified Endodontic Techniques. Compendium 2003;24(1):930-942. After two and a half years of endodontic instrumentation and obturation with the EZ-Fill bi-directional spiral and epoxy root canal cement, the EZ-Fill obturation technique gives the dentist predictable and easily attained success. Periapical areas demonstrated healing and any excess EZ-Fill cement is resorbing. Post-operatively, the patients are experiencing approximately 80% less pain in both occurrence and intensity. Musikant BL, Cohen BI, Deutsch AS. Alternatywna metodawypelniania kanalu korzeniowego: metoda pojedynczego cwieka. Twój Przeglad Stomatologiczny 2002;4:22-23. (Polish: The Single Point Technique: A Most Efficient Alternative For Endodontic Obturation.) An uncompromising standard for endodontic obturation has always been the intimate fit of the gutta percha to the walls of the root canal. Whether the obturation techniques involve lateral and vertical condensation or thermoplasticizing, the proximity of the gutta percha to the walls of the prepared canal has always been considered essential in establishing a thin cement interface between the gutta percha and the dentin, a necessary requirement for an optimum seal. A thin cement interface has traditionally been a requirement because most root canal sealers have weak matrices when set and are subject to rapid degradation when subjected to the oral fluids. The thinner the interface, the less likely that dissolving oral fluids will react with the cement especially given the hydrophobic nature of gutta percha. The innovation of one instrument, the EZ-Fill bi-directional spiral, has given the dentist control over the flow and direction of the root canal cement. By controlling the flow of a sealer with a matrix stronger than that of gutta percha, EZ-Fill epoxy-resin cement, the unnecessary complications introduced by lateral condensation and thermoplasticization are eliminated allowing the dentist to obturate quickly, thoroughly and easily with a much larger and more easily attained window of success. Deutsch AS, Cohen BI, Musikant BL. Investigating gutta percha and sealer distribution. Endodon Practice 2003:6(1):23-26. The purpose of this in vitro study was to investigate the sealer distribution in teeth instrumented and obturated using three different clinical techniques. Four teeth in three different groups (EZ-Fill SafeSider/EZ-Fill, Lateral

Condensation and Thermafil) were sliced in cross section, microscopically photographed and viewed on the computer. All groups for all sections demonstrated similar morphological appearances. The apical 1mm section all groups demonstrated a central core filling material surrounded by sealer. The central core material (gutta percha or plastic carrier) did not directly or totally contact the canal wall. However, in all sections the sealer closely adapted to the dentinal canal wall. In all three clinical techniques (EZ-Fill SafeSider/EZ-Fill, Lateral Condensation and Thermafil) the endodontic sealer is responsible for the complete obturation and hermetic sealing of the canal. The EZ-Fill SafeSider/EZ-Fill technique demonstrated a more uniform and predictable gutta percha to cement morphology at all levels of the canal. Lee KW, Williams MC, Camps JJ, Pashley DH. Adhesion of Endodontic Sealers to Dentin and Gutta-Percha. J Endodon 2002;28(10):684-688. Adhesion of endodontic sealers to dentin and gutta-percha offers clues into their interaction with the wall of the root canal and the filling materials. In this in vitro study, four classes of endodontic sealers (Kerr, a ZOE-based sealer; Sealapex, a calcium hydroxide-based sealer; AH-26, an epoxy resin-based system (similar in chemistry to EZ-Fill epoxy resin root canal cement);and Ketac-Endo, a glass-ionomer based sealer) were compared for their ability to bond to dentin or gutta-percha. Flat coronal dentin or gutta-percha surfaces were created by using a diamond-impregnated saw blade. Aluminum cylinders (ca. 5-mm diameter) were stabilized on the substrates with small amounts of wax and then filled with one of the sealers. After setting in 100% humidity for 24 hours, their tensile bond strengths were measured. Controls were the unfilled cylinders stabilized with wax. The bond strengths and modes of failure were measured. The results were statistically analyzed by using a two-way ANOVA (materials versus substrates) and Student-Newman-Keuls test. The results indicated that sealant bond strengths to dentin from lowest to highest mean ± SD, n=10) were: Kerr 0.13±0.02; Sealapex 0.30 ± 0.08; Ketac-Endo 0.80 ± 0.24; AH-26 2.06±0.53 MPa. The latter two were significantly different (p<0.05) from the first two sealers and from themselves. The sealant bond strength to gutta-percha (from the lowest to highest mean ± SD) were; Ketac-Endo 0.19± 0.01; Sealapex 0.22 ±0.01; Kerr 1.07 ± 0.19; AH-26 2.93 ± 0.29 MPa. AH-26 gave the significantly highest bond strength to gutta-percha.


Musikant BL, Cohen BI, Deutsch AS. Comparison instrumentation time of conventional reamers and files versus a new non-interrupted flat-sided design. J Endodon 2003 ;30:107-109. This in vitro study measured the time (in seconds) required to instrument and shape canals by conventional reamers and files compared to a newly introduced reamer and file system. This experiment was divided into four groups with ten block samples for each group. The results of instrumentation time demonstrates that the non-interrupted flat-sided design (EZ-Fill SafeSider reamers) produced the fastest times for comparably shaped canals. This is a consequence of reduced engagement of the instrument with the walls of the canal compared to conventional instruments. The conventional designs for both reamers and files results in increased instrumentation time compared to their EZ-Fill SafeSider counterparts. Tagger M, Tagger E, Tjan AHL, and Bakland LK, Shearing Bond Strength of Endodontics Sealers to Gutta-percha. J Endodont 2003;29(3):191-193. Strength of the bond of root canal sealers to gutta-percha seems to be an important property for maintaining the integrity of the apical seal. In the few studies published, different models and assessment methods were used. The purpose of our study was to adapt an effective and easily reproducible model and to test it on nine contemporary commercially available endodontic sealers. Gutta-percha disks with a diameter of 10 mm and thickness of 2 mm were prepared by warming gutta-percha cones and then fixed with plaster in 1-inch phenolic rings. Five-millimeter long sections of polyethylene tubing, filled with freshly mixed sealer, were placed on the gutta-percha and tested for shearing bond strength after setting. A custom-made holder was attached to the rings and placed in an Instron machine, which was activated at a cross-arm speed of 0.5 mm per minute. The bond strength ranged from 0 Mpa to 6.4 MPa. (AH26 being among the highest bond strength with Roth and Sealapex having no bond strength to gutta percha or dentin). The sealers were ranked, and those that did not differ statistically in their bond strength were grouped together. This model provides for measuring the in vitro bond strength if endodontic sealers. Kont Cobanaka F, Altinoz H C, Belli S. Adhesion of a Newly Developed Sealer to Dentin . J Dent Res 82 (Special Issue B (Goteborg Abstracts)):Abstract #2669,2003. Aim: Adhesion of root canal sealers to dentin is an important property for long term success of the root canal sealer by maintaining the integrity of the seal of root canal fillings. The purpose of this study was to evaluate dentin adhesion of a recently developed sealer RC Sealer

comparing with commercial root canal sealers, RoekoSeal, silver-free AH26 and Ketac-Endo. Material and Methods: 60 extracted human non-carious third molar teeth were used. The crowns were cut from the middle third and pulp chamber roof dentin surfaces were used for tensile strength test. Root canal sealers were placed onto the specimens’ surface at an angel of 90 degree by the help of a specially designed steel apparatus and allowed to set for 7 days in an incubator providing a moist atmosphere at a temperature of 37ºC. This set-up was then placed into a steel frame which was designed for Testometric Universal Testing Machine. Tensile strength values were measured, calculated as MPa and evaluated statistically. Results: The results of the study revealed that there were not statistically significant difference among RC Sealer and AH26 (p>0.05). RoekoSealer’s adhesion was also similar that of Ketac-Endo (p>0.05). However both adhesion of RC Sealer and AH26 were better than Ketac-Endo and RoekoSeal (p<0.05). (Note EZ-Fill epoxy root canal cement is a AH26 derivative). Conclusion: It was concluded that all of the tested materials have adhesive properties however RC Sealer and AH26 have better adhesion potential when compared to Ketac-Endo and RoekoSeal. Musikant BL, Cohen BI, Deutsch AS. Introduction of EZ-Fill SafeSider Endodontic Instruments. Cont Esthet 2003;7(3):60-64. This article outlines endodontic procedures with the EZ-Fill SafeSider Instrumentation System and EZ-Fill Obturation System. The EZ-Fill SafeSider Instrumentation System creates a shape equivalent to that of rotary nickel-titanium crown-down procedures. The EZ-Fill Obturation System produces a three-dimensional fill that is indistinguishable from the best thermoplastic results and is solidly backed by the literature Musikant BL, Cohen BI, Deutsch AS. The EZ-Fill SafeSider approach to endodontic instrumentation. Dentistry (UK) 2003;Feb:15. This article outlines instrumention using rotary, traditional hand, and EZ-Fill SafeSider hand endodontic instrumentation systems. It reviews the weaknesses of rotary and traditional hand endodontic instrumentation in comparison to the EZ-Fill SafeSider Instrumentation system. This is due in most part by the use of the non-interrupted flat-sided EZ-Fill SafeSider reamers or files over non-relieved files. The EZ-Fill SafeSider reamer or file has significantly less contact with the walls of a narrow canal than that of a non-relieved file. The


use of the flat provides less resistance to reaching the apex due to the amount of contact the instrument makes with the canal walls. The less the contact, the less the resistance and the easier the apical progress. Musikant BL, Deutsch AS, Gu S. Criteria That Define The Ideal Mechanically Based Endodontic Instrumentation System. Compendium 2004;25(10A):817-818. An ideal endodontic instrumentation system should meet the following criteria: easily learned; readily adaptable to the entire range of endodontic procedures including significantly and abruptly curved canals; highly resistant to instrument separation; not inductive to hand fatigue; resistance to canal and Instrument distortion; time efficient & cost efficient. We use these criteria as a guide to make judgments on the various systems. Although cost efficient, Traditional endodontics is furthest from the ideal. Most shaping is limited to a .02 mm/mm taper which makes predicting excellent results almost impossible. The sequel to traditional endodontics, Rotary NiTi predictably produce 04 to 06 mm/mm tapers assuring adequate debridement and obturation. Rotary NiTi is time efficient and may be used in a wide variety of cases, however rotary NiTi does fall short of an Ideal mechanical system. It actually increases the chances of instrument separation, and the attempt to avoid these separations has added greatly to the cost of the systems. A hybrid system such as SafeSiders, places the emphasis on stainless steel shaping and uses NiTi only after 95% of the canal has been shaped. The system also includes use of the No. 2 Peeso and Gates Glidden to help shape the canals. The basic shaping instrument of the SafeSiders system is a relieved reamer. Advantages of the SafeSiders include, 2/3 less engagement with the dentinal walls than a nonrelieved file; flutes that are more vertical than those on a file and more efficiently used in a rotary/reciprocating fashion; two vertical blades that sweep the debris away; flexibility; & a cutting tip which prevents the resistance that non-end cutting files may encounter. The system is relatively easy to learn because separation is not a significant concern. The SafeSiders are adaptable to a whole range of endodontic situations. Canal distortion does not occur because the SafeSiders sequence routinely straightens the coronal curve reducing the distorting effect of the apically placed safesiders. The incorporation of the 60º to 90º reciprocating hand piece as the driver for the SafeSiders allows the efficient and safe shaping of canals with the complete elimination of hand fatigue in even the most difficult of cases. Musikant BL, Deutsch AS. Endodontic Techniques DEFINED BY PRINCIPLES. NYSDJ 2004: April. Traditional endodontics, limited to the use of K-files, has proven so inefficeient in achieving predictable superior results that it deficiencies led to the development and adioption of rorary NiTi systems that produce far superior results, often with much less physical effort. However, in tight curved canals, the inherent weakness

of rotary NiTi to both torsion and cyclic fatigue has let to a troubling number of fractured instruments lodged in the canals. The introduction of the SafeSider instrumentation system eliminates the problems of both traditional K-file instrumentation and the fractured instruments associated with rotary NiTi, while delivering superior results in a time-efficient manner. Shipper G, Teixeira FB, Trope M. An Evaluation of Microbial Leakage I Roots Filled with a Thermoplastic Synthetic Polymer-Based Root Canal Filing Material (Resilon). J Endont 2004;30(5):342-347. The purpose of this study was to compare bacterial leackage using Streptoccus mutans and Enterococulas faecalis through gutta-percha and thermoplastic synthetic polymer-based root filing (Resilon) using two filling techniques during a 30-day period. Teeth were decoronated, roots prepared to a length of 16mm and instrumented to ISO sizes 40 to 50. A total of 156 roots were randomly divided into 8 groups of 15 roots (groups 1-8) and 3 control groups (12 roots each). Roots were filled using lateral and vertical condensation techniques with gutta-percha and AH 26 sealer (groups 1 and 2) or with gutta-percha and Epiphany sealer (groups 3 and 4). Groups 5 and 6 were filled with Resilon and Epiphany sealer using the lateral or vertical condensation techniques. A split chamber microbial leakage model was used in which S. mutans placed in the upper chamber could reach the lower chamber only through the filled canal. Groups 7 and 8 were identical to groups 5 and 6 respectively; however, E. faecalis was used to test the leakage. Positive controls were filled with Resilon (12 roots) and gutta-percha (12 roots) without sealer and tested with bacteria, whereas negative controls (12 roots) were sealed with wax to test the seal between chambers. All but one positive control leaked within 24 h, whereas none of the negative controls leaked. Resilon showed minimal leakage (group8; one leakage; groups 5-7: each with two leakages), which was significantly less that gutta-percha, in which approximately 80% of specimens with either technique or sealer leaked. Kruskal-Wallis test showed statistical significance when all groups were compared (p<0.05). Mann-Whitney U test compared the respective groups and found Resilon groups superior to gutta-percha groups (p<0.05). Musikant BL. The Evolution of Endodontic Progress, Making Excellence a Reflection of Simplicity. Dentistry Today 2005; April: 118-122. This article demonstrates the evolution of endodontic progress from hand held instruments to rotary to reciprocation.


Reciprocation with relieved reamers offers the following advantages over rotary Ni-Ti.:

• The instruments are subject to far less torsional stresses.

• The instruments are subject to far cyclic fatigure.

• Appling excessive apical pressure is far less critical.

• Lingering apically too long is far less critical. • Negotiating curved canals does not increase the

chances of separation. • The tips of the reamers may be bent to negotiate

abrupt curves. • Less tooth structure is removed from the canals. • Tactile perception is maintained throughout the

procedure. • The instruments can be used multiple times

without separation concerns. • Hand fatigue is eliminated while maintaining

instrument integrity. • Cost is dramatically reduced on a per-use basis. • Most importantly, the confidence level of the

practitioner is greatly increased. There is nothing gimmicky about using these instruments in the prescribed manner. Steps cannot be skipped, and each instrument must accomplish its task before the next one in the sequence is used. However, if these easily learned steps are followed, then excellent, predictable, and efficiently achieved results are within the grasp of all who use the system. Technical Profile: AN INSIDE LOOK FROM THE MANUFACTURER. Clinical Success of reciprocating One-visit Endodontic Cases. Inside Dentistry, March 2006 This article shows the progression of the use of the SafeSider system through a sequence of radiographs. Stuart CH, Schwartz SA, Beeson TJ, Owatz CB. Enterococcus faecalis: Its Role in Root Canal Treatment Failure and Current Concepts in Retreatment. J Endodont 2006;32:93-98. Enterococcus faecalis is a microorganism commonly detected in asymptomatic, persistent to endodontic infections. Its prevalence in such infections ranges from 24% to 77%. This finding can be explained by various survival and virulence factors possessed by E. faecalis, including its ability to compete with other microorganisms, invade dentinal tubules, and resist nutritional deprivation. Use of good aseptic technique, increased apical preparation sizes, and inclusion of 2% chlorhexidine in combination with sodium hypochlorite are currently the most effective methods to combat E. faecalis within the root canal system of teeth. In the changing face of dental care, continued research on E. faecalis and its elimination from the dental apparatus may well define the future of the endodontic specialty. Studies indicate the prevalence of E. faecalis is low in primary endodontic infections and high persistent infections. E. faecalis is also more commonly associated

with asympotomatic cases with symptomatic ones. Although E. faecalis possesses several virulence factors, its ability to cause periradicular disease stems from its ability to survive the effects of root canal treatment and persist as a pathogen in the root canals and dentinal tubules of teeth. Our challenge as endodontic specialists is to implement methods to effectively eliminate this microorganism during and after root canal treatment. Currently, use of good aseptic technique, increased apical preparation sizes, and inclusion of full strength sodium hypochlorite and 2% chlorhexidine irrgants are the most effective methods to eliminate E. faecalis. Recent studies have helped us better understand E. faecalis and the mechanisms that enable it to cause persistent endodontic infections. In the changing face of dental care, continued research on E. faecalis and its elimination from the dental apparatus may well define the future of the endodontic specialty. Wu M-W, van der Sluis LWM. Wesselink. A 1-year follow-up study on liakage of single-cone fillings with RoekoRSA Sealer. Oral Surg Oral Med Oral Pathol Oral Radiol 2006;101:662-7 Objective. The aim of this study ws to measure long-term leakage along single cone (SC) fillings. Study design. Two groups of canines (n=30) were prepared and a size 55 file was the apical master file. Step-back was performed using files of sizes 60, 70 and 80. The canals were filled by the single cone technique using roekoRSA as a sealer. To place sealer into each canal, a bidirectional spiral was used in 1 group, whereas a gutta-percha cone was used in the other group. Immediately after root filing, the coronal portion of root filing was removed by a postspace preparation. Leakage along the 4 mm remaining apical root filing was measured after 1 week and again after 1 year using a fluid transport model. Ten additional canine roots were prepared and filled with gutta-percha cones with out sealer, serving as positive contros. Occurrence of apical extrusion of materials was recorded. Results. The apical root filing in all 60 canine roots did not show leakage either at 1 week or at 1 year. All 10 positive controls showed gross leakage (>20µL/h). In no case gutta-percha extruded through the apical foramen. Sealer extruded apically in 88% of the roots where a gutta-percha cone was used to introduce sealer, whereas in 28% of the roots where a bidirectional spiral was used to introduce sealer by (chii-square test, P</05). Conclusion. In wide and straight canals, SC filings with RoekoRSA sealer prevented fluid transport for 1 year. Using bidirectional spiral to place sealer reduced sealer extrusion under the conditions of this experiment. Musikant BL, Deutsch AS


The Virtue of Common Sense In Endodontics. Dentistry Today 2006;25:72-77. August 01, 2006 Abstract: Conclusion: This article makes the case that rotary Ni-Ti should not be compared with traditional techniques. There is no question that rotary Ni-Ti outperforms these antiquated systems. Rather, the comparison should be between this new alternative way to accomplishing endodontic treatment and rotary Ni-Ti . As so many former rotary Ni-Ti users who now use this alternative method of instrumentation have found out, all the advantages of rotary Ni-Ti are retained, while the disadvantages of both traditional techniques and rotary Ni-Ti are virtually eliminated. When one considers the fact that the cost of doing endodontics drops by about 90% on a per-use basis when this alternative system is employed, without sacrificing quality, the motivation to grow acquainted with this system becomes obvious. Musikant, BL, Deutsch AS More Effective Endodontics Than Rotary NiTi Oral Health, October 2006 87-92 This article starts out telling you what not to do while doing a root canal then it changes course and states how to instrument the canals properly Parashos, P Messer, HH Rotary NiTi Instrument Fracture and its Consequences J Endod 2006;1031-1043 Abstract: The fracture of endodontic instruments is a procedural problem creating a major obstacle to normally routine therapy. With the advent of rotary nickel-titanium (NiTi) instruments this issue seems to have assumed such prominence as to be a considerable hindrance to the adoption of this major technical advancement. Considerable research has been undertaken to understand the mechanisms of failure of NiTi alloy to minimize its occurrence. This has led to changes in instrument design, instrument protocols, and manufacturing methods. In addition, factors related to clinician experience, technique and competence have been shown to be influential. From an assessment of the literature presented, we derive clinical recommendations concerning prevention and management of this complication. Martin AP ANATOMICAL BARRIERS IN ENDODONTICS* Ann R Aust Coll Dent Surg 1997;11:82-95 Abstract: Endodontic therapy can be challenging at the diagnostic and technical levels. The more one can advance one’s accomplishments, the more that would-be barriers cease to be so. Difficult aspects of tooth isolation and assessment of root integrity cab be rendered less problematic by some relatively simple methods. Gaining a clear awareness of the internal layout of a coronal chamber and any possible inclusions can be assisted by use of a modified endodontic explorer. It can be usefully employed to resolve the

common dilemma of whether openings at the base of a molar or malillary premolar coronal access cavity are exposures in the pulp chamber roof or orifices in the chamber floor. Locating and then gaining full working length entry into partly calcified canals, even when they are not radiographically discernible, remains one of the difficult tasks in endodontic therapy, but methods can be implemented that maximize their successful negotiation and management. The use of fine engine-driven reamers, but absolutely restricted to a reciprocating action hand piece, is described. Wolcott S, Wolcott J, Ishley D, Kennedy W, Johnson S, Minnich S, Meyers J Seperation Incidence of Protaper Rotary Instruments: A Large Cohort Clinical Evaluation J Endod 2006:1139-1141 Abstract: Separation is a potential risk when using any instrument in the root canal system. Presently, there are no large clinical studies investigating the separation incidence of the ProTaper rotary file system or the number of times a ProTaper rotary file can be safely used. The purpose of this study was to determine if the number of uses affects the separation incidence of ProTaper rotary instruments. 4652 consecutively treated root canals were performed in an endodontic group practice over a 17-month period. Both the separation incidence and the number of uses were tracked for each file. The overall rate of instrument fracture in this study was 2.4% with no significant differences over the first four uses. The results of this study indicate that ProTaper rotary files may be safely reused atleast four times. The size of the rotary file, among other factors, will determine how many times a particular file should be used. Roggendorf MJ, Ebert J, Dennerlein M, Frankenberger, Petschlet A. Abstract #2856 Coronal and Apical Microleakage of Root Canal Fillings With/Without Gutta Percha. University of Erlangen-Nuremberg, Germany Hawaii Convention 2004 Objectives: The aim of the present study was to evaluate the effect of the sealer layer thickness on apical and coronal microleakage of root canal filings with four different root canal sealers. Methods: 120 extracted single rooted lower incisors were instrumented up to .04/45. Smear layer was removed using 40% citric acid. Teeth were divided into four groups (n=30) of sealers; grp1: AH Plus ® (DeTrey-Densply, Konstanz, Germany), grp2:EndoRez® (Ultradent Corp., South Jordan, UA, USA), grp3: EZ-Fill® (Essential Dental Systems, South Hackensack, NJ, USA), grp4: Rely-X Unicem® (3M-Espe, Seefeld,


Germany), combined with various gutta-percha cones:

Group 1 2 3 4 5 6 7 8 9 10 11

12

Sealer AH Plus EndoREZ EZ-Fill Rely-X Unicem

cone

.04/40

.02/40

none

.04/40

.02/40

none

.04/40

.02/40

none

.04/40

.02/40

none

The root ends were removed and the teeth seprated into a coronal and apical half. After coating with nail varnish with exception of the apical cutting area, the teeth were centrifuged within 5% methelyne blue dye (30g/3min). Linear dye penetration was evaluated by two independent investigators using a stereo microscope. Statistical analysis was computed using SOSSwin® 11.0 (SPSS Inc., Chicago, IL, USA). Results: Means of linear dye penetration were (in mm, with SD):

groups

1 2 3 4 5 6 7 8 9 10 11 12

apical

2.1/0.7

1.4/0.4

2.2/0.8

2.3/0.9

2.9/1.2

3.6/1.5

1.4/1.0

1.7/0.8

1.8/0.5

1.5/0.8

2.51/1.4

2.2/0.9

coronal

1.8/1.1

2.0/1.0

2.5/0.9

3.8/2.1

5.4/1.4

6.3/1.5

2.4/1.6

2.7/1.7

2.8/2.4

1.9/0.9

2.5/1.4

2.6/1.6

Statisitical analysis revealed significant differences among the groups (Kruskal-Wallis test, ;<0.001). Microleakage was significantly influnced by sealer and gutta-percha cones (multifactorial ANOVA;p<0.05). Conclusions: AH Plus and EZ-Fill showed best performance, EndoRez was the weakest. Regarding our data, Rely-X Unicem may be used as a sealer. Eldeniz AU, Mustafa K, Ørstavik D, Dahl JE.

Cytotoxicity of new resin-, calcium hydroxide- and silicone-based root canal sealers on fibroblasts derived from human gingiva and L929 cell lines.

Int Endod J. 2007 May;40(5):329-37.

AIM: To assess ex vivo the cytotoxic effects of five new root canal sealers (RC Sealer, Epiphany, EndoREZ, GuttaFlow and Acroseal) and three existing products (AH Plus, RoekoSeal and Apexit) using primary human gingival fibroblasts (HGF) and a mouse fibroblast cell line, L929. METHODOLOGY: Eight samples of each sealer were fabricated in sterile cylindrical Teflon blocks, 4.4 mm diameter and 2 mm height and then divided into two groups, fresh and aged specimens. Extraction of fresh specimens was carried out after setting whilst aged specimens were placed in Petri dishes and kept in a humid chamber at 37 degrees C for 7 days before extraction in cell culture medium using the ratio 1.25 cm(2) mL(-1). Undiluted eluates were used for the dimethylthiazol diphenyltetrazolium bromide (MTT) assay with HGF and L-929. Morphology of HGF cells

was also examined by an inverted microscope using undiluted eluates of the sealers. The results were analysed using a two-tailed t-test (alpha = 0.05) between groups. RESULTS: Resin-based (Epiphany and EndoREZ) and calcium hydroxide-based (Apexit and Acroseal) sealers were significantly more cytotoxic than other sealers (P<0.05). However, L929 cells were more sensitive to Apexit and EndoREZ than HGF cells. RC Sealer showed mild cytotoxicity to HGF at both setting times. AH Plus did not exert any cytotoxic effect to HGF and aged specimens appeared to induce cellular proliferation. RoekoSeal and GuttaFlow also demonstrated mild cytotoxicity. GuttaFlow was slightly more cytotoxic to both cultures, especially when tested fresh. CONCLUSIONS: Toxicity varied but RC Sealer and GuttaFlow were the least toxic new sealers.

SafeSiders

By: Barry L. Musikant and Allan S. Deutsch

Regardless of what system is used to shape canals, the goal is to render a canal devoid of as much tissue as possible, producing a shape that can be obturated as close to 100% as possible. Knowing that tissue in canals can be in a variety of invaginations that prevent its physical removal, we also want to create a shape that allows the efficient introduction of chemical irrigants that will digest physically untouched tissue not removed thru instrumentation and kill any remaining bacteria that are present in that tissue and the dentinal tubules.

The goal is very clear. The way to attain that goal is subject to much discussion. Much of what we want to accomplish comes under the category of what not to do. Included in this list is:

* Minimizing canal distortion along the entire length of the canal.

* Preventing instrument separation in the canal.

* Neither over-instrumenting nor under-instrumenting.

If we prevent the above three procedural error and thoroughly debride the canals, our results will produce successful results on a predictable basis.

Let us examine a few different approaches to instrumentation and obturation to see their potential for meeting our goals.


The use of traditional files used in a stepback fashion often produced canal shapes that inadequately prepared the middle third of the canal where many of them open wide bucco-lingually. The use of k-files often bind excessively in the apical third impacting debris and impeding complete negotiation to the apex.

The blockage of canals in the apical third often leads to overzealous pressure being applied to these instruments in an effort to gain apical length. Depending on the degree of curvature in these canals, excessive apical pressure and rotation can lead to apical distortion to the outer wall of the canal or worse, a complete lateral perforation of the root (Fig. 1).

Apical distortion may produce a shape where the most apical preparation is wider than the shaping coronal to it, producing a blunderbuss, which is difficult to obturate effectively (Fig. 2).

Given the increasing resistance to k-files in curved canals as the files become wider, many canals are under-instrumented simply because preparing the canals to a wider diameter is too difficult and if attempted leads to greater distortions. The consequences of minimal shaping leads to inadequate irrigation leaving more tissue in the canal that can support bacterial growth while preventing subsequent effective obturation.

Rotary NiTi instrumentation is essentially a crown-down technique which widens the more coronal aspects of the canal before going more apically with thinner and less tapered instruments. Crown-down limits the amount of engagement that any one instrument encounters as it negotiates apically. The NiTi instruments are about three times more flexible than stainless allowing a thicker instrument to negotiate apically without the same potential for distortion.

Rotary NiTi requires two conditions to be met before they can be safely used. First, the access opening must allow for straight line access to approximately half way down the root. If this condition is not met, the potential for the instrument to separate at the coronal end of the flutes increases significantly. Two, the entire distance to the apex must have an unencumbered glide path most often created with the hard to use k-files.

A sufficient glide path is one where a minimum of a No. 20 file will slide to the apex of the canal with a push motion. If this glide path is not established, the potential for separation in the apical third of the instrument is also increased (Fig. 3).

Short of achieving these two goals, instrumentation must be done by alternative means. This may include the use of peeso and gates glidden reamers, the use of hand filing in the apical third and a host of other alternatives from Hedstroms to ultrasonics.

While separated instruments can be reduced thru the use of conservative alternatives, it is their vulnerability under a host of different circumstances, that makes the dentist most cautious when they are used. The consequences of this reality include rapid replacement of these expensive instruments and a learning curve that truly expands on when not to use them in the first place.

Balanced against the anxiety produced by unpredictable separation is the fact that when they perform well, they produce shapes that are far superior to anything that traditional techniques routinely produced.

The next logical step is to produce a system that is free of separations, yet produces shapes that clean the canals at least as well as rotary NiTi. To meet that standard, a set of instruments must be used that negotiate to the apex with far less resistance than the k-files. Relieved reamers accomplish this goal creating a glide path thru a 20. There is far less resistance to apical negotiation because there are fewer flutes to engage the walls of the dentin, the flutes are more efficient at removing dentin from the walls of the canal because they are more vertically oriented and the relief along the length of the shank produces two columns of chisels that cut in both the clockwise and counterclockwise direction (Fig. 4).

These relieved hand reamers may be used either manually or in a 30 degree reciprocating handpiece taking full advantage of the efficient clockwise-counterclockwise cutting potential of the two columns of chisels plus the vertically oriented flutes.

Motion limited to a 30 degree arc (Fig. 5) virtually eliminates torsional stress and cyclic fatigue the two most important factors in the separation of rotary NiTi instruments.

Using these relieved reamers in the reciprocating handpiece, allows the rapid creation of a glidepath with an apical preparation of 0.20mm. A glidepath of this dimension is more than enough to guide a tapered peeso down the canal. The purpose of the tapered reamer is primarily to straighten the coronal curve at the expense of the outer wall, thereby leaving the tooth structure on the furcal side of the canal intact. Ideally, the peeso should get within 6mm of the apex which is roughly half way down the root. The tapered peeso is thinner at the tip than a conventional No. 2 peeso and consequently goes to length with less resistances and less ability to bottle.


Once the coronal curve is straightened all that is usually left even in a complicated molar is an apical curve. Because of the peeso, the subsequent relieved reamers used either manually or in the reciprocating handpiece need only negotiate one curve, not two making their apical progress that much more rapid and their potential for apical distortion far less.

The canals are most often instrumented to a 35 to the apex and 40 1mm short of the apex.

Now that 95% of the canal has been shaped with tough inexpensive stainless steel instruments, the remaining 5% is shaped with two NiTi relieved reamers with its use limited to the motion of the reciprocating handpiece.

As a result, they are highly unlikely to separate even if firm, but fleeting apical pressure is applied. The net result is a minimal preparation of 35 at the apex with a modified 08mm/mm taper, a shape that is most efficiently irrigated and obturated with epoxy-resin cement and either a medium or a 30/06 gutta percha point.

This entire sequence represents a complete alternative to rotary NiTi. The tapered peeso is a more efficient instrument than any rotary NiTi instrument because it can follow the natural architecture of the coronal wall of the canal space in both a mesio-distal and bucco-lingual direction. Rotary's need to stay centered rather than working the walls selectively limits their ability to clean asymmetrically shaped canals.

The more ubiquitous work of the tapered peesos allow for better irrigation than that created by rotary NiTi. The fact that instruments are far less likely to separate even in curved canals, allows for a greater degree of instrumentation which cleans the canals better and produces a space that is again more efficiently irrigated.

With minimal exposure to torsional stress and cyclic fatigue, all these relieved reamers may be used several times without concern for separation. In fact, they are replaced simply because they become dull after several uses and if abused by overuse they simply will cut less efficiently without an increased incidence of separation. As a result the dentist using this type of system will spend less than 1/10 the cost of rotary NiTi which are recommended by the manufacturers to be used once and discarded.

Even in unusually curved canals these tough inexpensive instruments may be pre-curved and placed into canals manually, still 3 to 4mm shorter than the apex, negotiated around the curve and then reattached to the reciprocating handpiece.

Pre-curved instruments cause no distortion when placed into the curved canals even when used in the

reciprocating handpiece because a 30 degree envelope of motion is too constricted to scribe a sufficient arc beyond the confines of the canal the instrument is already in. This is certainly not the case for rotary NiTi where the last thing one can do is pre-bend an instrument.

Rotary NiTi is a tremendous improvement over traditional techniques and deserves a place as a tool that increased the effectivness of endodontics. However, it has been replaced by alternative systems, that have none of rotary NiTi's vulnerabilities while producing results that are at least as good as rotary NiTi.

Given the reduced costs of these alternative systems, their simplified learning curve and their far superior resistance to separation, one can easily envision the day where rotary NiTi, today's paradigm technique, will no longer be relevant.

Dr.'s Musikant and Deutsch are fellows of the American College of Dentistry (FACD). Dr. Musikant is the president, Dr. Deutsch is the executive vice-president as well as co-directors of Research at Essential Dental Systems.

Iqbal MK, Ku J

Instrumentation and Obturation of the Apical Third Canals: Addressing the Forgotten Dimension

Compendium June 2007;28(6):314-321

Abstract: Modern developments in instrument design and obturation techniques have greatly improved the efficiency of conventional endodontic therapy. Nickle titanium rotary instruments allow the practitioner to prepare canals more quickly and predictably. However, apical preparations by such instruments fail to address the anatomical complexity of the root canal system. Morphologic studies consistently show that canals are mostly oval irregular in shape; therefore, round preparations by instrumentation result in uninstrumented areas of the root canal system. This is of particular importance in the apical third and in cases of preexisting periapical pathology, where residual bacteria may reside and cause persistent infections. How beneficial are these new instrumentation and obturation techniques to the basic purpose of root canal therapy in eradicating bacteria? This article presents the shortcomings of current instrumentation and obturation techniques and offers possible solutions to improve the out come of endodontic therapy.


The author concludes that the flat sided instruments are an endodontic benefit.

Rodig T, Hulsmann M, Kahlmeier C

Comparison of root canal preparation with rotary NiTi instruments: ProFile .04 and GT Rotary

International Endodontic Journal, 40, 553-562, 2007

Aim: To compare root canal preparation using ProFile.04 and GT Rotary nickel-titanium instruments (both Densply Maillefer, Ballaigues, Switzerland).

Methodology: Fifty extracted mandibular molars with esial root canals curvatures between 20 and 40º were randomly divided into two groups and embedded in a muffle system. All root canals were prepared to size 45 using a ProFile .04 or GT rotary instruments. The following parameters were evaluated: straightening of root canal curvature, postoperative root canal cross section, cleaning ability, safety issues and working time.

Results: Both NiTi systems maintained curvature well: the mean degree of straightening was <1º. The majority of the root canals prepared with ProFile .04 (80.8%) and GT (84.0%) postoperatively showed a round or oval cross-section. For debris, ProFile .04 and GT rotary achieved a 67.1% and 71.6% scores of 1 and 2, respectively. Concerning the coronal region statistical analysis showed a better result for GT than for ProFile .04. For the middle and apical thirds of the root canals, results did not differ significantly. None of the two systems completely removed the smear layer. Ten procedural incidents occurred with ProFile .04 compared with five GT. Mean working time was shorter for ProFile .04 (131.8 s) than for GT (143.7 s); the difference was not significant.

Conclusions: Both systems respected original root canal curvature well and were safe to use. Smear layer removal was not satisfactory with either systems.

These systems remove more tooth structure than the SafeSider system.

Musikant BL, Cohen BI, Deutsch AS Comparison Instrumentation Time of Conventional Reamers and Files versus a New, Noninterupted, Flat-sided Reamer Journal of Endodon 2004;30,(2):107-109 This in vitro study measured the time required to instrument and shape canals by conventional reamers and files compared with a newly introduced reamer and file system. This experiment was divided into four groups with 10 block samples for each group. The results of instrumentation time demonstrate that the noninterrupted flat-sided design (EZ-Fill SafeSider reamers) produced the fastest time for comparable

shaped canals because of reduced engagement of the instrument wit the walls of the canal compared with conventional instruments. The conventional designs for both reamers and files result in increased instrumentation time compared with their EZ-Fill SafeSider counterparts. Eldeniz AU, Mustafa K, Orstavik D, Dahl JE Cytotoxicity of new resin-, calcium hydroxide and silicone-based root canal sealers on fibroblasts derived from human gingival and L929 cell lines Int Endod J. 2007 May;40(5):329-37 Aim: To assess ex vivo the cytotoxic effects of five new root canal sealers (RC Sealer, Epiphany, EndoRez, GuttaFlow and Acroseal) and three existing products (AH Plus, RoekoSeal and Apexit) using primary human gingival fibroblasts (HGF) and a mouse fibroblast cell line, L929. Methodology: Eight samples of each sealer were fabricated in sterile cylindrical Teflon blocks, 4.4 mm diameter and 2 mm height and then divided into two groups, freshed and aged specimens. Extraction of fresh specimens was carried out after setting wilst aged specimens were placed in Petri dishes and kept in a humid chamber at 37 degrees C for 7 days before extraction in cell culture medium using the ratio 1.25 cm(2) mL(-1). Undiluted eluates were used for the dimethylthizolium bromide (MTT) assay with HGF and L-929. Morphology of HGF cells was also examined by an inverted microscope using undiluted eluates of the sealers. The results were analysed using a two-tailed t-test (alpha = 0.05) between groups. Results: Resin-based (epiphany and EndoREZ) and calcium hydroxide-based (Apexit and Acroseal) sealers were significantly more cytotoxic than other sealers (P<0.05). However, L929 cells were more sensitive to Apexit and EndoREZ than HGF cells. RC Sealer showed mild cytotoxicity to HGF at both setting times. AH Plus did not exert any cytotoxic effect to HGF and aged specimens appeared to include cellular proliferation. RoekoSeal and GuttaFlow also demonstrated mild cytotoxicity. GuttaFlow was slightly more cytotoxic to both cultures, expecially when tested fresh. Conclusions: Toxicity varied but RC Sealer and GuttaFlow were the least toxic new sealers.


H.Y. Li, C.-K. Park, S.J. Jung, S.-Y. Choi, S.J. Lee, K. Park, J.S.Kim, S.B. OH Eugenol Inhibits K+Currents in Trigeminal Ganglion Neurons J Dent Res 86(9):898-902, 2007 Eugenol, a natural capsaicin congener, is widely used in dentistry. Eugenal inhibits voltage-activacted Na+ and Ca2+ channels in a transientreceptor potential vanilliod 1 (TRPV1) – independent manner. We hypothesized that eugenol also inhibits voltage-gated K+ currents, and investigated this in rat trigeminal ganglion neurons and in a heterologous system using whole-cell patch clamping. Eugenol inhibited voltage-gated K+ currents, and the inhibitory effects of eugenol were observed in bothcapsaicin-sensitive and capsaicin-insensitive neurons. Pre-treatment with capsazephine, a well known antagonist of TRPV1, failed to block the inhibitory effects of eugenol on K+ currents, suggesting no involvement of TRPV1. Eugenol inhibited huan Kv 1.5 currents stably expressed in Ltk ¯ cells, were TRPV1 is not endogenously expressed. We conclude that eugenol inhibits voltage-gated K+ currents in a TRPV1-independent manner. The inhibition of voltage-gated K+ currents is likely to contribute to the irritable action of eugenol. Abbreviations: human Kv1.5 channel, hKV1.5: transient receptor potential vanilliod 1, TRPV1. Paque F., Sirtes G Apical sealing ability of Resilon/Epiphany versus gutta-percha/AH Plus: immediate and 16-months leakage International Endodontic Journal 40, 772-729, 2007 Aim: To compare the long-term apical sealing ability of gutta-percha/AH Plus and Resilon/Epiphany. Methodology: The root canals of 90 single-rooted human mandibular premolars with single narrow root canals were prepared woth ProFile 0.4 taper instruments to apical size 40. After each instrument, the canals were irrigated with 1% sodium hypochlorite. Subsequently, the teeth were randomly divided into four groups containing 20 teeth each. Additionally, 10 prepared premolars served as positive and 10 counterparts with intact crowns as negative controls. The root canals were filled with gutta-percha/AH Plus or Resilon/Epiphany using lateral or vertical compaction. Specimens were allowed to set for 7 days at 37ºC and 100% humidity. Subsequently the root fillings were removed down to the apical 4 mm. Fluid movement was then assessed using a fluid transportation model and re-evaluated after 16 months of water storage. Leakage within and between groups was compared using non parametric tests. Results: Negative controls revealed no fluid movement and positive controls displayed gross fluid movement at both times of observation. At the immediate measurement, there were no significant differences between the experimental groups (Kruskal-Wallis, P > 0.05). Gutta-percha/AH Plus filings retained their seal after 16 months storage (Wilcoxon, P > 0.05), whilst the resilon/Epiphany groups lost their sealing capacity (Wilcoxon, P <0.001). In these groups 29 of the 40

specimens exhibited gross leakage similar to positive controls. Conclusion: Initially, Resilon/Epiphany root fillings prevented fluid movement to the same degree as gutta-percha/AH Plus counterparts, but showed more fluid movement when tested at 16 months. Rasimick BJ, Shah RP, Musikant BL, Deutsch AS Radiopacity of Endodontic Materials on Film and a Digital Sensor J Endod 2007;33:1098-1101 The purpose of this study was to compare the radiographic appearance of 12 endodontic materials as visualized on either Kodak Ultra-speed D speed film (Eastman Kodak Company, Rochester, NY) or a Gendex eHD digital sensor (Gendex Dental Systems, Milan, Italy). Ten discs of each material were radiographed along an aluminum alloy 1100 (Alcoa, Pittsburgh, PA) stepwedge that was used for reference. For every radiograph, the average grayscale value of the material was converted into absorbance notation and compared with that of the reference stepwedge in order to determine the equivalent radiopacity in terms of millimeters of Al 1100 per millimeter of material. Two-way repeated-measures analysis of variance testing detected significant differences with respect to imaging system, material, and the interaction of the two factors (p < 0.001). The difference in a material’s radiopacity as measured on the digital sensor compared with film was greater than 10% for 4 of the 12 materials and over 40% for InnoEndo (Heras Kulzer, Armonk, NY). It was speculated that barium fillers cause this effect. Mamootil K, Messer HH Penetration of dentinal tubules by endodontic sealer cements in extracted teeth in vivo International Endodontic Journal,2007:40:873-881 Aim: To compare the depth and consistency of penetration of three different root canal sealer cements into dentinal tubules in extracted teeth and to measure the penetration of an epoxy resin-based sealer cement in vivo. Methodology: Root canals of 50 extracted human pre-molar teeth were prepared and obturated using three different sealer cements based on epoxy resin (AH21), zinc oxide eugenol (Pulp Canal Sealer EWT) and methacrylate resin (EndoREZ). Five teeth filled without sealer were used as controls. Teeth were sectioned and prepared for observation using scanning electron microscopy. A further 12 teeth with a history of successful root filling and subsequent extraction were collected and sectioned. The depth of sealer penetration into dentinal tubules was measured and the consistency


and appearance of the sealer within the tubules observed. Results: AH26 demonstrated the deepest penetration (1137um) and Pulp Canal Sealer EWT (71um). The difference in penetration between all sealer groups was found to be statistically significant (P<0.05). The resin-based sealers appeared to penetrate tubules more consistently. In the clinical cases, all teeth demonstrated sealer penetration to varying depths (98-1490 um). Conclusions: The depth and consistency of dentinal tubule penetration of sealer cements appears to be influenced by the chemical and physical characteristics of the materials. Resin-based sealers displayed deeper and more consistent penetration. Penetration depths observed for the epoxy resin-based sealer in vivo were consistent with that found in the experimental model. Jainaen A, Palamara JEA, Messer HH Push-out bond strengths of the dentine-sealer interface with and without a main cone International Endodontic Journal 2007:40:882-890 Aim: To evaluate the push-out bond strength of the dentine-sealer interface with and without a main cone for three resin sealers. Methodology: Thirty extracted maxillary premolar teeth with two separate canals were prepared using 0.04 taper Profile instruments to size 35-45. Teeth were divided into three groups for filling using AH Plus™, EndoREZ® or Resilon® sealers. In each tooth, one canal was filled with a matching single-cone technique, and other was filled with sealer alone. A 1 mm slice of mid-root dentine was prepared for the push-out test. Failure Modes after Push-out were examined under microscopy and field emission-scanning electron microscopy. Data were analysed using two-way ANOVA and paired t-tests, with significance set at P<0.05. Results: Overall, the epoxy resin-based sealer provided the highest push-out bond strengths. Push-out bond strengths were significantly higher (P,0.001) when canals were filled with sealer alone than those filled with main cone and sealer (AH Plus™ 6.6 and 2.0 MPa, respectively: Resilon® 3.4 and 0.4 MPa; Endo-REZ® 0.9 and 0.4 MPa). Sealers appeared to behave differently as thin films in association with a main cone, compared with bulk material. They failed in cohesive mode within the thin film, leaving a layer of sealer on the canal surface. Bulk sealer showed predominantly adhesive failure at the dentin-sealer interface, with a clean dentine wall and with resin tags either partially pulled out or sheared off at the interface. Conclusion: Push-out bond strengths of resin sealers were much lower when the sealer was present as a thin layer. Rasimick BJ, Shah RP, Musikant BL, Deutsch AS Radiopacity of Endodontic Material on Film and a Digital Sensor J Endod 2007;33:1098-1101 The purpose of this study was to compare the radiographic appearance of 12 endodontic materials as visualized on either Kodack Ultra-speed D speed film

(Eastman Kodack Company, Rochester, NY) or a Gendex eHD digital sensor (Gendex Dental Systems, Milan, Italy). Ten discs of each material were radiographed alongside an aluminum alloy 1100 (Alcoa, Pittsburgh, PA) stepwedge that was used for reference. For every radiograph, the average grayscale value of the material was converted into absorbance notation and compared with that of the reference stepwedge in order to determine the equivalent radiopacity in terms of millimeters of Al 1000 per millimeter of material. Two-way repeated-measures analysis of variance testing detected significant differences with respect to imaging system, material, and the interaction of the two factors (p < 0.001). The difference in a material’s radiopacity as measured on the digital sensor compared with film was grater than 10% for 4 of the 12 materials and over 40% for InnoEndo (Heraus Kulzer, Armonk, NY). It was speculated that barium fillers cause this effect. Gu S, Rasimick BJ, Deutsch AS, Musikant BL Radiopacity of dental materials using a digital X-ray system Dental Materials 22 (2006) 765-770 Objectives: Radiopacity is a desirable property for most intra-oral materials. There are established ISO and ANSI/ADA protocols for determining radiopacity using film-based radiography. However, these methods are not always followed by researchers. This study aims to adapt those procedures by using digital radiography, a simplified stepwedge, and examine the effects of target distance and exposure and time choice. Methods: One millimetre thick samples of three dental materials were prepared by placing the materials into a 1.00 mm thick washer sandwiched between two glass slides. The samples were digitally radiographed alongside a stepwedge of aluminum alloy 1100 with an X-ray unit at 70kVp using five different target distance/exposure time combinations. For each combination, the grey scale values of various thicknesses of the stepwedge were converted into absorbencies and plotted against their thickness. These plots were then linearly regressed in order to correlate absorbance with a thickness of aluminum for each target distance/exposure time combination. The absorbencies of each sample were then converted into radiopacities using these correlations. Results: The correleations between the absorbance of the stepwedge and its thickness were highly linear. This linearity allows the correlation to be accurately deduced from fewer data points than required by the ISO and ANSI/ADA protocols. Varying exposure time did not significantly affect the mean radiopacity measured at a target distance of 30cm. Varying the target distance did not significantly affect the measured radiopacity as long as the samples were properly exposed.

GLOVE' N CARE® and SCRUB’N GLOVE® LIQUID SOAP 6/1

GLOVE'N CARE® HAND CREAM and SCRUB’N GLOVE® LIQUID SOAP Glove'n Care hand cream is specifically formulated with ingredients mined from the mineral rich Dead Sea. The source of natural skin care secrets for over 2,000 years. Theses minerals have been combined with a special combination of oils to create a very ESSENTIAL skin care product. Hand cream relieves dermal sensitivity Deutsch AS, Cohen BI, Musikant BL. Dentistry Today 1995; July:20-21. There has been an increasing concern regarding hypersensitivity reactions to operatory gloves. By far latex gloves were the most common cause of problems. The most common reactions were a) itching and/or redness on contact area; b) dry skin on contact area; and c) cracking skin on contact area. Recent work has brought to light a number of interesting facts concerning hydration of the stratum corneum. For example, it has been found that the stratum corneum contains water-soluble compounds responsible for the wetability, water-holding and water-absorbing capacities of this tissue, which are called collectively "Natural Moisturizing Factor" of skin, or simply NMF. Glove'n Care hand cream contains all of the minerals present in NMF. Glove'n Care contains an effective hygroscopic moisturizer, water of high saline content. It does not cause burning, stinging, or other unpleasant sensations and is well tolerated on the lips and skin. It is non-irritating and does no damage to the stratum corneum, even after repeated applications. The Dental Advisor Plus. July/August 1995;Vol. 5:No. 4. Glove'n Care ++++ 1/2 (Essential Dental Systems, Inc. 89 Leuning Street, So. Hackensack, NJ 07606). TDA PLUS Recommendation Glove'n Care is a highly recommended skin care cream developed specifically for dental professionals who wear latex gloves. It received a 91% approval rating. Description Glove'n Care is a water-based, hypoallergenic skin care cream used for protection of hands adversely affected by talc and residues found in latex gloves, as well as minor dermatitis caused by continued exposure to soaps and other chemicals. It is packaged in a non-collapsible, white plastic tube with

a flip-top cap. Dental personnel in 15 practices evaluated Glove'n care over a 90-day period. Positive Features Consultants rated Glove'n Care at a 99% level for the feel of skin after application. A very small amount is needed, and it is readily absorbed. A single application is effective over several washing and glovings, and Glove'n Care does not interfere with donning or removing gloves. Long-term skin response also rated well. Personal preference influenced evaluation of the scent, from "pleasant" to "perfumey." The tube has a clean, professional look, can be opened and closed readily with one hand, and stands upright on its cap so cream is easily dispensed. Consultants Comments - Best hand cream I've tried yet! - Good length of protection - Light fragrance - Not oily, but can be a bit greasy if too much is applied Ratings Excellent +++++ Very Good ++++ Good +++ Clappison RA. Those Hands, Those Hands, Those PRICELESS Hands. Oral Health June 97;87(6):29-30. With up to 29 percent of dental professionals reporting dry, inflamed hands there is no doubt about the adverse effects of gloving. The problems are mainly of the irritant contact dermatitis type. The allergies are reported to be increasing. Latex, the main source of sensitivity contains chemicals such as thiuram accelerators, antioxidants, surfactants, sulphur by-products and acids. Since most latex is from the natural source latex gloves can include organic contaminants such as fungi, bark, lichen, molds and as many as 100 different proteins. If you are having hand problems keep in mind that the progression from irritant contact dermatitis to allergic dermatitis does occur over time so protect those priceless hands. Glove’n Care (a soothing, hypoallergenic hand cream with minerals mined from the Dead Sea) is recommended for use before and after gloving. Glove’n Care is scented, nongreasy, and contains various oils, emulsifying wax, aloe vera gel, Dead Sea water for healing, glycerin, allantoin, dimethicone etc. The author found it to be very beneficial.


Cohen BI, Pagnillo MK, Musikant BL, Deutsch AS. Evaluation of the Electrical Permeability of Hand Creams Applied to Latex Gloves. Gen Dent 1997;45(6):592-598. The purpose of this study was to measure the electrical conductivity on latex gloves when they are in contact with commercial hand creams. One hundred twenty-five gloves were allotted to groups of five. For each group of gloves except the control group, a pea-sized amount of hand cream was applied to each digit. The gloves were allowed to sit for one week before electoconductivity testing. The testing apparatus consisted of an electrode inside a vessel filled with an electrolyte solution. Gloves were filled with and placed into the electrolyte solution, and electrodes were placed outside and inside the gloves. Two-way analysis of variance (ANOVA) statistics was applied to the electoconductivity data and upon finding a significant difference with ANOVA, the Student-Newman-Keuls (SNK) pairwise multiple comparison test was used to determine which specific treatment conditions differed from one another. These analyses showed that gloves differed significantly (p<.0001), as did hand creams (p<.0255). Further analysis with the SNK test showed that each of the three gloves differed from each other. Henry Schein brand gloves had the greatest glove integrity and Defend brand gloves had the least. Both Glove’n Care and Septodont brands were statistically less likely to affect the integrity of the latex gloves than Henry Schein hand cream, Keri, Neutrogena, Oil of Olay, and Vaseline. Henry Schein hand cream, Keri, Neutrogena, Oil of Olay, and Vaseline brands were not statistically different from one another. Clinical Research Associates Newsletter, Glove’n Care Hand Cream. (120) 1997;21(10):4. EVALUATION SUMMARY: Rating of hand creams involves strong personal preferences, & only occasionally can a group of clinicians reach consensus on this type product. Glove’n Care had exceptionally high rating among dentists & staffs from 34 field sites. Following advantages are noted: (1) Relieved effects of dry skin well for 74% of users; (2) Did not leave greasy film when sued correctly (dispense small amount & allow 30 sec. to absorb); (3) Left hands smooth & soft with only one case of irritation reported in user group; (4) Long lasting (effects withstood several washings); & (5) CRA Evaluators noted water base rather than petroleum base created minimal latex glove interaction. Fragrance was noted as excellent by 46%. Overall rated excellent or good & purchase recommended by 88% of CRA Evaluators.

Deutsch AS, Cohen BI, Pagnillo MK, Musikant BL. Evaluation of Electrical Permeability Integrity of Latex Gloves with Hand Creams. J Dent Res 1998;[Abstract 290] 142. The purpose of this study was to measure the electrical conductivity on three latex gloves (Henry Schein, Baxter, and Defend) when they are in contact with seven commercially available hand creams (Glove 'n Care, Henry Schein hand cream, Keri, Neutrogena, Septodont hand cream, Oil of Olay, and Vaseline) plus three glove control groups without hand cream applied. This study consisted of 24 groups with 5 specimens per group for a total of 120 specimens. All groups, except the control groups, had a pea size amount of hand cream applied on each digit. These gloves were allowed to sit for one week before electroconductivity testing. A testing apparatus consisted of a 1800 mL vessel filled with 900 mL of a 0.9% by weight salt saline solution which was used as an electrolyte and a rigid plastic cylinder to hold the specimen suspended in the electrolyte solution. Gloves were placed over the rigid plastic cylinder and this was placed into the electrolyte solution. The glove was then filled to just below the plastic cylinder (200 mL) with of the electrolyte solution. An ohm meter (43-Range Multitester) with one probe placed at the bottom of the vessel and the other placed in the glove through the open end of the cylinder was used to test the electroconductivity of the gloves. After a 10 minutes interval a reading was taken from the ohm meter. The data was then tabulated. A two-way ANOVA followed by a Student-Newman-Keuls (SNK) pairwise multiple comparisons test was used to determine significant difference. Results were consider statistically significant if p<0.05. The statistical analyses showed that gloves differed significantly (p<0.0001) as did hand creams (0.0255). Henry Schein had the greatest glove integrity and Defend had the worst glove integrity. Both Glove 'n Care and Septodont were statistically less likely to affect the integrity of the latex gloves than Henry Schein hand cream, Keri, Neutrogena, Oil of Olay, or Vaseline. Henry Schein Hand cream, Keri, Neutrogena, Oil of Olay, and Vaseline were all similar and were not statistically different from one another. 1998 CRA Dental Product Buying Guide.CRA-Clinical Research Associates Newsletter. 1998;22(1):2&4. Products which were highly rated after clinical field trials, long term clinical testing and lab testing: Glove’n Care- Excellent overall grade & purchase indicated


Harvey Report Inc. Reader Profile Study for RDH Magazine. Aug. 28, 2000:58-64. The study results come from the circulation list of RDH magazine. Glove’n Care as well as other dental hand creams were surveyed (256 respondents) and Glove’n Care represented the third most band used (16%).

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EDS’ PULP-OUT BUR Deutsch AS, Cohen BI, Musikant BL. Morphological measurements of anatomic landmarks in human maxillary and mandibular molar pulp chambers. J Endodon 2004;30:388-390. The aim of this in vitro study was to measure critical morphology of molar pulp chambers. One hundred random human maxillary and mandibular molars (200 teeth in total) were used. Each molar was x-rayed mesio-distally on a millimeter grid. Using a stereomicroscope, the measurements were read to the nearest 0.5 mm. Results were (Maxillary = Max, Mandibular = Mand, Mean (mm)): Pulp Chamber Floor to Furcation; Max=3.05 ± 0.79, Mand=2.96 ± 0.78 ;Pulp Chamber Ceiling to Furcation; Max =4.91 ± 1.06,Mand=4.55 ± 0.91; Buccal cusp to Furcation: Max=11.15 ± 1.21,Mand=10.90 ± 1.21 ; Buccal cusp to pulp chamber floor; Max=8.08 ± 0.88,Mand=7.95 ± 0.79; Buccal cusp to pulp chamber ceiling; Max=6.24 ± 0.88,Mand=6.36 ± 0.93; pulp chamber height; Max=1.88 ± 0.69,mand=1.57 ± 0.68 . The pulp chamber ceiling was at the level of the cemento-enamel junction in; Max=98%,Mand=97% of the specimens.The measurements showing the lowest percentage variance were, buccal cusp to furcation (approximately 11%) and buccal cusp to pulp chamber ceiling (approximately 14%). The measurements were similar for both maxillary and mandibular molars. post and patented system, designed to provide easy post removal and access to the apex, in the event of a failed root canal. With the special retreatment drills, retreatment now becomes a routine, non-surgical procedure. The second tier provides high retention, stability and even distribution of stresses under function, thus preventing the high apical stresses common to traditional passive posts. Musikant BL, Deutsch AS, Gu S, Isidro, Mario. Morphological Measurements of Anatomic Landmarks in Pulp Chambers of Human Maxillary furcated Bicuspids. J Endodont 2005; 31(8): 570-573 The aim of this study was to measure key morphological features of pulp chambers from furcated maxillary bicuspid teeth. There were 107 random human maxillary bicuspid teeth used. Each bicuspid was radiographed using the Trophy RVG digital imaging system and a Belmont Acuray X-ray at 70 kVp. Measurements were made using the Digipan measuring mode of the Trophy system. The measurements showing the lowest percentage variance were: cusp to furcation (9.7%) and cusp to pulp

chamber ceiling (10.09%). The only measurement that was statistically the same across maxillary molars, mandibular molars and bicuspids was measurement “B,” pulp chamber ceiling to furcation. The critical distance from cusp tip to pulp chamber ceiling in bicuspids was approximately 7.00 mm. Deutsch AS, Musikant BL. Endodontic Preparations, Accessing the pulp chamber without perforating the furcation using the PulpOut Bur System. Dental Products Reports 2004 July This article contains step-by-step procedures for using the PulpOut Bur system to access normal and calcified pulp chambers without perforating the furcation. Weathers AK, Six secrets of efficient endodontics. Dental Magic 2004;2 The purpose for this article is to give information to perform root canals with accessing the canal with the PulpOut Bur. Deutsch AS. Pulp Chamber Morphology – Basic Research Leads to Clinical Technique. Dentistry Today 2005 March. This article contains information regarding the pulp chamber measurements in both maxillary and mandibular molars and bicuspids. Deutsch AS, Musikant BL. Essential Dental Systems Product Profile: PulpOut Bur Technique. DentalTown Magazine. October 2004;44-48. This article contains rules to follow to access the pulp chamber. There are two rules to follow:

1. One or more cusps tips of the tooth must be intact (either natural or crowned) in order for the PulpOut bur to attain the proper depth. If a tooth is either missing the cusps for measurement or the cups are appreciably worn down from attrition or the tooth is prepared for a crown DO NOT use the PulpOut bur.

2. Always cut WET. Technique: Using water spray, in teeth with furcations and at least one cusp tip, drill the access opening into the pulp. If the tooth is restored with a porcelain restoration use a diamond bur first to go through porcelain. Make a rough outline of the pulp chamber using the PulpOut bur. The correct depth has been reached when the circular stop of the PulpOut drill is prevented from further apical movement by any remaining cusp tips. Refine the axial walls of the access preparation using the non-end cutting diamond “Shaper” bur. This is done by leaning the diamond shaper against the axial wall and going around the entire access opening

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outline. This smoothes the axial walls, lets more light in and makes it easier to find the canals. You are now ready to look for the canals. Dr. Hany M. Makkawy, Kathryn Alderman & Elizabeth Chaloupek, Don’t Perf Out PulpOut. Presentation at University of Nebraska Medical Center, College of Dentistry. 2006 This study was performed to evaluate if the PulpOut Bur will extend into the pulp chamber of maxillary and mandibular molars and to determine if the PulpOut Bur prevents perforations during access openings in molars. Extracted molars (including calcified teeth) were used: 44 Maxillary & 59 Mandibular. In maxillary molars, the tip of the bur was at the middle of the pulp chamber in 70.5% and at the floor of the chamber in 29.5% In mandibular molars, the tip of the bur was at the middle of the pulp chamber in 17.0% and at the floor of the chamber in 83.0% These results showed the pulp chamber was reached in all teeth. No perforations occurred Deutsch AS, Musikant BL Find Canals Faster through Basic Research NYSDJ August/September 2006 Abstract: Achieving access and finding canals are the key first steps in the endodontic procedure. This has always been a time-consuming, qualitative procedure that relies on the dentist’s experience and feel. Recent basic research has been published that shows hat the anatomic morphological measurements concerning the pulp chamber are very consistent in every tooth. This research points the way to a quantitative, predictable and quick technique for making endodontic access preparations without risk. The research and clinical technique are described in this article. Lee MM, Rasimick BJ, Turner AM, Shah RP, Musikant BL, Deutsch AS Morphological Measurements of Anatomic Landmarks in Pulp Chambers in Human Anterior Teeth J Endod 2007;33:129-131 This in vitro study measured key morphological features of pulp chambers in anterior teeth and tested the hypothesis that the distance from the lingual surfice (midpoint from the cusp tip to the lingual CEJ) to the pulp chamber (the midpoint form the buccal to the lingual CEJ) was similar for different tooth types. Extracted human teeth were sorted and 100 samples of each of the following tooth types were chosen: maxillary central incisor (UCI), lateral incisor (ULI), and canine (UC), as well as mandibular central incisor (LCI), lateral incisor (LLI), and canine (LC). All teeth were digitally radiographed on a 1-mm X-ray grid. The

mean values of measurement C, the distance from the lingual surface to the pulp chamber, varied significantly between tooth types (p < 0.001). The mean values and SNK rankings were as follows: LC (5.9 + 0.5 mm) > UC (5.5 + 0.5) = UCI (5.0 + 0.4) > LLI (4.8 + 0.5) > LCI (4.4 + 0.4).

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Irrigation Stuart CH, Schwartz SA, Thomas JB, Christopher, BO. Enterococcus faecalis: Its Role in RootCanal Treatment Failure and CurrentConcepts in Retreatment J Endod 2006;32:93-98 Enterococcus faecalis is a microorganism Commonly detected in asymptomatic, Persistent endodontic infections. Its prevalence in such infections ranges From 24% to 77%. This finding can be Explained by various survival and virulence Factors possessed by E. faecalis, including Its ability to compete with other microorganisms, Invade dentinal tubules, and resist nutritional Deprivation. Use of good aseptic technique, Increased apical preparation sizes, and inclusion Of 2% chlorhexidine in combination with Sodium hypochlorite are currently with most Effective methods to combat E. faecalis Within the root canal systems of teeth. In The changing face of dental care, continued Research on E. faecalis and its elimination From the dental apparatus may well define The future of the endodontic speciality. Sassone LM, Fidel R, Vieira M & Hirata R. Jr. The influence of organic load on the antimicrobial activity of different concentrations of NaOCl and chlorhexidine in vitro. International Endodontic Journal 2003;36:848-852. Aim: To evaluate bacterial growth after contact with sodium hypochlorite (NaOCl; 1 and 5%) and chlorhexidine (CHX; 0.12, 0.5 and 1%) with or without the addition of organic material (bovine serum albumin (BSA) 0.5%). Methodology: Bacterial samples (American Type Culture Collection® (ATCC) of Staphylococcus aureus, Enterococcus Faecalis, Escherichia coli, Porphyromonas gingivalis and Fusobacterium nucleatum were kept in contact with each irrigating solution for varying intervals of time: immediately (t0), 5 min (t5), 15mn (t15) and 30 min (t30). Each test was repeated 10 times. In half of the specimens, 0.5% BSA was added as organic material in an attempt to simulate the organic tissue present in the root-canal system. Bacterial Growth under appropriate condition of incubation was evaluated and compared for each microorganism at all time intervals. Results: A 0.12# CHX solution did not eliminate E. faecalis at any time interval. One percent CHX eliminated all strains, as did both NaOCl

concentrations. BSA did not interferesubstantially with the antimicrobial activity of the irrigating solutions. Lin Y-H, Mickel AK, Chogle S. Effectiveness of Selected Materials Against Enterococcus Faecalis: Part 3. The Antibacterial Effect of Calcium Hydroxide and Chlorhexidine on Enterococcus Faecalis. Journal of Endod 2003;29:565-566. It has been found that Entercoccus faecalisis most commonly isolated in failed endodontic treatment. Irrigation with chlorhexidine gluconate has been suggested based on its antimicrobial effect and substantivity. Calcium hydroxide also is an effective antimicrobial agent because of its high alkalinity. The purpose of this study was to test the individual and combined effect of calcium hydroxide and chlorhexidine against E. faecalis. The agar-diffusion test was performen on Mueller-Hinton plates. Paper disks were impregnated with: (a) CaOH powder with sterile water; (b) Pulpdent®; (c) 0.12% Peridex®; (d) CaOH powder with Peridex® and (e) Pulpdent® with Peridex®. Ampicillin servedas a control. The plates were incubated at 37ºC for 72 h, Peridex® showed significantly larger zones of inhibition compared with CaOH. No statistically significant difference was found between Peridex® and the combination of CaOH and Peridex® Basrani B, Tjaderhane L, Santos JM, Pascon E, Grad H Lawrence HP, Freidman S. Efficacy of chlorhexidine- and calcium hydroxide-containing medicaments against Enterococcus faecalis invitro. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;96:618-24. Objective. We sought to asses the efficacy of chlorhexidine (CHX) and calcium hydroxide, Ca(OH)2, against Entrococcous faecalis in vitro. Study design. The effect of CHX (0.2% and 2% in gel or solution) and Ca(OH)2 (alone or with 0.2%CHXgel) wasevaluated by using the agar diffusion test and an invitro human root inoculation method, to measure zone of inhibition or bacterial growth with optical density analysis, respectively. For optical density analysis samples from infected root canals were collected after 7 days of medication and were cultured for 24 hours in brain-heart infusion to detect viable bacteria. Results. In the agar diffusion test, CHX was effective against E faecalis in a concentration-dependent fashion, butCa(OH)2 alone had no

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effect. In the root canal inoculation test, CHX was significantly more effective against E faecalisthan Ca(OH)2 was (P<.05), but there were no significant differences between the modes of medication or concentrations of CHX. Conclusions. CHX is effective against E faecalis in vitro. Futhter in vivo studies are needed to confirm the value of CHX in clinical treatment. Zamany A, Safivi K, Spangberg LSW. The Effect of chlorhexidine as an endodontic disinfectant. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;96:578-81. Objective. The purpose of this study was to establish whether addition of a 2% chlorhexidine rinse to a conventional treatment protocol enhances the rate of the successful disinfection of the root canal system invivo. Study design. Twenty-four teeth with infected necrotic pulps and resorbing apical peridontitis were treated with a conventionas technique in which 1% NaOCL as irrigant was used. Half of the cases received an additional rince with 2% chlorhexidine. Prereduced thiglycollate medium was used to take cultures that were incubated for 4 weeks. Results. Cultivable bacteria were retrieved at the conclusion of the first visit in 1 out of 12 chlorhexidine cases wheras in the control group 7 out of 12 cases showed growth. This difference was significant (P<.05). Conclusion. The findings are clinically important. Oncag O, Hosgor M, Himiloglu S, Eronat C, Burhanoglu D. Comparison of antibacterial and toxic effects of various root canal irrigants. International Endodontic Journal 2003;36:423-432. Aim. To compare the antibacterial properties and toxicity of 5.25% Sodium hypochlorite(NaOCl), 2% chlorhexidine gluconate and 0.2% chlorhexidine gluconate pluce 0.2% cetrimide (Cetrexidin®; Vebas, San Giuliano, Milan, Italy), Methodology. The antibacterial effects of the irrigants in vitro were examined after 5 min and 48 h in freshly extracted human teeth with single roots, whose canals were infected by enterococcus faecalis ATCC29212. In a separate in vivo study, bacterial culture samples were collected before treatment from the infected root canals of deciduous teeth containing necrotic pulp tissue. Irrigants were used to clean the canals which were then left empty for 48 h.

Aerobic/facultative anaerobic and anaerobic bacterial growth were compared before and 48 h after irrigation. Finally, the toxic effects of the irrigants were assessed by injecting them into the subcutaneous ctissues of rats. The inflammatory reactions that occurred in 2 h , and 48 h and 2 weeks after the injections were evaluated. Results. In the laboratory study, the 2% chlorhexidine gluconate and the Cetrexidin® were significantly more effective on E. faecalis than the 2.25% NaOCl at 5 min(P<0.05). Similarly, in the in vivo study, 2% chlorhexidine gluconate and Cetrexidin® were significantly more effective on anaerobic bacteria than the 5.25% NaOCl at48 h (P<0.05). At the end of 2 weeks, the toxicity of the NaOCl solution was greater than that of the other irrigants (P<0.05). Conclusions. Cetrexidin® and 2%chlorhexidine gluconate were more effective, and had more residual antibacterial effects and lower toxicity than 5.25% NaOCl solution. Podibielski A, Spahr A, Haller B. Additive Antimicrobial Activity of Calcium Hydroxide and Chlorhexidine on common Endodontic Bacterial Pathogens. Journal of Endodontics 2003;29:340-345. It is an established procedure to use calcium hydroxide [CA(OH)2] as a therapeutic component to achieve sterilization of infected root canals. Unfortunately, some bacterial species are relatively resistant to Ca(OH)2 and therefore associated with treatment failures. The objective of this study was to identify combinations of substances that improve antimicrobial activity. Ca(OH)2 was used as a suspension or as a component of gutta-percha points. Efficacy of killing was compared for (a) Ca(OH)2 suspension alone; (b) zinc oxide (ZnO) points alone; (c) Ca(OH)2 suspension combined with ZnO points; (d) Ca(OH)2 Suspension combined with ZnO/chlorhexidine points; and (e) Ca(OH)2 points combined with ZnO/chlorhexidine points. Common endodontopathogenic bacterial species (Enterococcus Faecalis, Fusobacterium nucleatum, Peptostreptococcus micreo, Porphyomonas gingivalis, Streptococcus intermedius) in pure cultures served as target organisms. In the in vitro assay, the antibacterial substances and approximately 107 colony forming units of test bacteria were co-incubated in diluted human serum under growth conditions appropriate for the single bacterial species. Samples were taken on days 0, 1, 2, 4, 7, and 14 of incubation and viable counts determined.

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Gram-negative bacteria were sufficiently killed by Ca(OH)2 alone. Combinations with other agents did not improve the killing kinetics. For the inactivation of the Gram-positive bacteria P. micros and S. intermedius, a combination of Ca(OH)2 and ZnO/chlorhexidine, killed the bacteria faster than Ca(OH)2 alone. For E. faecalis, combining Ca(OH)2 suspension with ZnO/chlorhexidine points lead to a faster decrease in the overall number of viable bacteria, but no test conditions lead to the complete loss of culture viability. The results of this study support the use of a combination of a Ca(OH)2 and chlorhexidine for faster eradication of P. micros and S. intermedius from infected root canals. Vianna ME, Gomes BPFA, Berber VB, Zaia AA, Ferraz CCR, Jose de Souza-Filho F. Invitro evaluation evaluation of the antimicrobial activity of chlorhexidine and sodium hypochlorite. Oral Surg Oral Med Oral Pahtol Oral Radiol Endod 2004;97:79-84. The aim of this study was to investigate in vitro the antimicrobial activity of 0.2%, 1% and 2% chlorhexidine gluconate (CHX gel and CHX liquid), aginst endodontic pathogens and compare the results with the ones achieved by 0.5%, 1%, 2.5%, 4% and 5.25% sodium hypochlorite (NaOCl). A broth dilution test was performed, and the timing for irrigants to kill microbial cells was recorded and statistically analyzed. Both 2.0% gel and liquid formulations eliminated Staphylococcus aureus and Candida albicans in 15 seconds, whereas the gel formulation killed Enteroccous faecalis in 1 minute. All tested irrigants eliminated porphyomonas endodontalis, Porphyromonas gingivialis, and Prevotella intermedia in 15 seconds. The timing required for 1.0% and 2.0% CHX liquid to eliminate all microorganisms was the same required for 5.25% NaOCl. The antimicrobial action is related to type, concentration, and presentation form of the irrigants as well as the microbial susceptibility. Menezes MM, Valera MC, Jorge AOC, Koga-Ito CY, Camargo CHR, Mancini MNG. In vitro evaluation of the effectiveness of irrigants and intracanal medicaments on microorganisms with root canals. International Endodontic Journal 2004;37:311-319. Aim. To evaluate in vitro the effectiveness of sodium hypochlorite (NaOCl), chlorhexidine

(CHX) and five intracanal medicaments on microorganisms within the root canals. Methodology. Ninety-six human single-rooted extracted teeth were used. After removing the crowns, canal preparation was completed and the external root surfaces were coated with epoxy resin. Following sterilization, the teeth were contaminated with Candia albicans and Enteroccous faecalis, and were incubated at 37± 1ºC for 7 days. The teeth were divided according to the irrigant solution or intracanal medicament: group 1. sterile physiologic solution (SPS) and calcium hydroxide(Ca(OH)2) paste; group 2, SPS and camphorated paramonochlorophenol (CPMC); group 3, SPS and tricresol formalin; group 4, SPS and CaOH2 + CPMC paste; group 5 SPS and PMC furacin; group 6 2.5% NaOCl without intracanal medication; group 7, 2.0% CHX without intracanal medication and group 8, SPS without intracanal medication (control group). Microbiological samples were collected with sterile paper points, and bacterial growth was determined. The data were submitted to the analysis of variance (ANOVA, P=0.05). Results. For C. albicans. Groups 3 and 8 were statistically less effective than groups 1, 2,4 and 5 (Kruskal-Wallis (K-W) 65.421;gl=7;P=0.001). For E faecalis, groups 6 and 8 were statistically less effective than groups 1-4 and 7 (K-W = 61.048;gl=7:P=0.001). Conclusions. Ca(OH)2 + CPMC paste was the most effective intracanal medicament for the elimination of the two microorganisms; 2.0% CHX solution was more effective than 2.5% NaOCl against E. faecalis. Rosenthal S, Spangerg L, Safavi K. Chlorhexidine substantivity in root canal dentin. Oral Surg Oral Med Oral Pahtol Oral Radiol Endod 2004;98:488-92. Objective. The purpose of this investigation was to evaluate the substantivity of chlorhexidine (CHX) within a root canal system and to asses how long the CHX remains antimicrobially effective. Study design. Bovine roots were sectioned and standardized to 8mm. Sections, which served as controls, were treated with 1% sodium hypochlorite and I mol/L EDTA, then obturated with gutta percha and AH26 sealer. Experimental sections were treated similarly except they were placed in 2% CHX for 10 minutes prior to obturation. Control specimens were divided into 4 control groups and stored in saline for 1 day, 3 weeks, 6 weeks and 12 weeks.

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Experimental specimens were divided into 4 groups and stored in saline for 1 day, 3 weeks 6 weeks and 12 weeks. After their respective storage periods, all specimens were halved and canal wall dentin was ground out with Peeso reamers. Dentin specimens were agitated in 700 µl of saline for 5 hours to release CHX. After Centrifugation the supernatants were analyzed with UV spectrophotometry at 253 nm. To determine whether the CHX from the dentin samples remained antimicrobial, the extracts from experimental and control groups were mixed with cultures of Enterococcus faecalis. Results. After 1 day of storage, the dentin extract contained approximately 0.0048% CHX. After 3, 6, and 12 weeks, dentin extracts contained approsimately 0.0023%, 0.0016% and 0.0010% CHX respectively. Extracts from the storage groups were found to be highly antimicrobial corresponding to the CHX concentration. Conclusion. The results of this study indicate that CHX is retained in root canal dentin in antimicrobially effective amounts for up to 12 weeks.

CarrilhoMRO, Carvalho RM, de Goes MF, di Hipolito V, Geraldeli S, Tay FR, Pashley DH, Tjaderhane L.

Chlorhexidine Preserves Dentin in vitro

J Dent Res 86(1):90-94, 2007

Loss of hybrid layer integrity compromises resin-dentin bond stability. Matrix metalloproteinases (MMPs) may be partially responsible for hybrid layer degradation. Since chlorhexidine inhibits MMPs, we hypothesized that chlorhexidine would decelerate the loss of resin-dentin bonds. Class I preparations in extracted third molars were sectioned into two halves. One half was customarily restored (etch-and-rinse adhesive/resin composite), and the other was treated with 2% chlorhexidine after being acid-etched before restoration. Specimens were stored in artificial saliva with/without protease inhibitors. Microtensile bond strengths and failure mode distribution under SEM were analyzed immediately after specimens’ preparation and 5 month later. With chlorhexidine, significantly better preservation of

bond strength was observed after 6 months; protease inhibitors in the storage medium had no effect. Failure analysis showed significantly less failure in the hybrid layer with chlorhexidine, compared with controls after 6 months. In conclusion, this in vitro study suggests that chlorhexidine might be useful for the preservation of bond strength.

Hebling J, Pashley DH, Tjaderhane, Tay FR

Chlorhexidine Arrests Subclinical degradation of Dentin Hygrid Layers in vivo

J Dent res 84(8):741-746, 2005

The recent paradigm that endogenous collagenoltic and gelatinolytic activities derived form acid-etched dentin result in degradation of hybrid layers requires in vivo validation. This study tested the null hypothesis that there is no difference between the degradation of dentin bonded with an etch-and-rinse adhesive and that in conjunction with chlorhexidine, an MMP inhibitor, applied after phosphoric-asid-etching. Contralateral pairs of bonded Class I restorations in primary molars of clinical subjects were retrieved after a six-month period of intra-oral functioning and processed for transmission electron microscopy. Hybrid layers from the chlorhexidine-treated teeth exhibited normal structural integrity of the collagen network. Conversely, abnormal hybrid layers were seen in the control teeth, with progressive disintegration of the fibrillar network, to the extent that it was beyond detection by collagen staining. Self-destruction of collagen matrices occurs rapidly in resin-infiltrated dentin in vivo and may be arrested with the use of chlorhexidine as an MMP inhibitor.

Hashimoto M, Tjaderhane L, Tay FR, Ito S, Pashley D

Effect of Chlorhexidine of MMP Activity of Human Dentin

2005 IADR/AADR/CADR 83rd General Session & Exhibition

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Objective: Several recent studies have suggested that collagen fibrils within the resin-dentin were hydrolyzed by MMP in human dentin matrix over the long-term. It should be possible to apply surface treatments to dentin to inhibit MMP activity before or during bonding procedure to increase the durability of resin-dentin bonds.

Purpose: We tested the null hypotheses that chlorhexidine (CH) treatment of dentin has no effect on MMP (collagenolytic and gelatinolytic) activity of human dentin.

Methods: extracted human molars free enamel, cementum and pulp were frozen in liquid nitrogen and reduced to dentin powder using a mixer mill. The denin powder was treated with either 0.5 EDTA or 37% phosphoric acid for 15 sec. Subsequently, the powder was then treated with different concentrations (0.002, 0.02, 0.2 or 2%) of CH for 15 or 60 sec. Powdered dentin was assayed for MMP activity using fluorescent and read in a fluorometer. Statistical analysis was performed by two-way ANOVA and fisher’s PLSD test (p<0.05).

Results:

Untreated 15 sec phosphoric acic

Powder CH 0.002% CH 0.02% CH 0.2% CH2%

Collagenase 191±32 75±15(a) 0±0(b) 0±0(b) 0±0(b)

Gelatinase 290±59 5±10(A) 0±0(B) 0±0(B) 0±0(B)

Untreated 15 sec EDTA

Powder CH 0.002% CH 0.02% CH 0.2% CH2%

Collagenase 191±32 158±21(a) 138±29(a) 0±0(b) 0±0(b)

Gelatinase 290±59 261±43(A) 133±22(B) 0±0(C) 0±0(C)

Units are relative fluorescence units RFU(Mean ± SD, N = *), Different letters indicate p<0.05.

Conclusions: CH treatment with high concentration, such as 0.2 or 2%, effectively reduced MMP activity of dentin. Based on these results, CH pre-treatment of dentin after acid-etching, may lead to improve durability of resin-

dentin bonds. Supported, in part, by USPHS grant DE014911, P.I. D. Pashley

Ito S, Saito T, Hashimoto M, Soeno K, Brackett H, Sano H, Tay FR, Pashley D

Effects of chlorhexidine of durability of dentin bonds

2006 AADR/ADEA

Objective: To evaluate the effect of chlorhexidine, a known inhibitor of MMPs, on the long term bond strengths of two dentin bonding systems.

Methods: Superficial occlusal dentin of thirty-six extracted human molars was used. Two adhesives: Single Bond (SB, 3M) and SE Bond (SEB, Kurray) were applied to dentin surfaces prepared with 320 grit abrasive paper after the application of 0%, 0.2%, 2% chlorhexidine (CHX). AP-X (Kurray) were used to creat resin composite buildups on bonded surfaces. After 24 hours storage in 37ºC water, the built –up teeth were sectioned perpendicular to the adhesive interface with a water-cooled slow-speed diamond saw to produce beams of approximately 0.9 mm2 in cross-sectional area. Beam samples were stored for 500 days in artificial saliva and then pulled to failure at 1 mm/min. Data was evaluated by three-way ANOVA (followed by multiple comparisona at a=0.05). Additionally, the modes of failures were observed using SEM.

Results: Microtensile bond strengths (mean±SD, n=13 in MPa) after 500 days. CHX concentration (%) 0 0.2 2 adhesive Single Bond 60.8 ±12.8a 78.6±12.3a,b 86.9±8.9b SE Bond 73.0±14.1a,b 78.1±12.5a,b 73.6±8.5a,b Means identified with the same superscript letters are not significantly different (p>0.05) using Fisher’s PLSD test. No statistically significant differences in bond strength values were found for specimens bonded with SE Bond. Bond Strengths created by Single Bond without CHX were lower in specimens that were pretreated with chlorhexidine. ANOVA reveled no difference among specimens bonded with SE

Irrigation 8/6

Bond (p=0.42), but a significant difference with Single Bond (p<0.05) specimens.

Conclusion: By simply applying chlorhexidine, the strength and duration of dentin adhesion created by Single Bond can be improved. Supported, in part, by DE 015306 from the NIDCR.

Rasimick BJ, Shah RP, Musikant BL, Deutsch AS Effect of EDTA conditioning upon the retention of fibre posts luted with resin cements International Endodontic Journal,41,1101-1106 Aim: To determine if a final rinse with EDTA improves the short-term in-tooth retentive strength of adhesively luted fibre-reinforced composite posts. Methodology: Six different commercial fibre post systems were tested. Post spaces in extracted human anterior teeth were irrigated with either 6% NaOCl or 6% NaOCl followed by 17% EDTA. Posts were luted using the manufacturer’s recommended bonding agent and luting cement. Two different sizes of posts were tested for each post system. After 24 h of storage, the retentive strength of the post to tooth (14 per group, 336 total) was tested using a pull-out technique. Three-way ANOVA and the Student-Newman-Kuels test were used to test the effects of irrigation regimen, post size and post brand on the retentive strength of the fibre post. Results: Almost every sample failed at the interface between dentine and luting cement. Irrigation method did not have any signivicant effect (P > 0.14) for any group other than the ParaPost Fibre White (P < 0.001). The overall retention of a post appeared to be correlated to the amount of surface texture on the post; the smooth ICEPost was the least retentive brand, the textured FibreKor and the ParaPost Fibre White posts were moderately retained, and the threaded Flexi-Post Fibre and the Flexi-Flange Fibre posts were the most retentive brands tested. For all brands, larger diameter posts were more retentive than smaller diameter posts (P < 0.008). Conclusions: A final rinse of EDTA did not improve the short-term retention of fibre posts except for ParaPost Fibre White.

Rasimick BJ, Nekich M, Hladek MM, Musikant BL, Deutsch Interaction between Chlorhexidine Digluconate and EDTA J Endod 2008;34:1521-1523 The combination of chlorhexidine and EDTA produces a white precipitate. The aim of this study was to determine if the precipitate involves the chemical degradation of chlorhexidine. The precipitate was produced and redissolved in a known amount of dilute trifluoroacetic acid. The amount of chlorhexidine and EDTA present in the dissolved precipitate was determined by reverse-phase high performance liquid chromatography (HPLC) with ultraviolet detection at 288 nm. More than 90% of the precipitate’s mass was found to be EDTA or chlorhexidine. The remainder is suspected to be water, gluconate, and sodium. Parachloroaniline, a potentially carcinogenic decomposition product of chlorhexidine, was not detected in the precipitate (the limit of detection was 1%). The molar ratio of dhlorhexidine to EDTA in the precipitate was about 1.6 to 1. Based on the results, chlorhexidine forms a salt with EDTA rather than undergoing a chemical reaction.

GENERAL RESEARCH 9/1

GENERAL RESEARCH Deutsch AS, Musikant BL, Cavallari J, Lepley JB. Prefabricated Dowels: A literature review. J Prosthet Dent 1983;49:998-503. This review evaluates post and core research, dealing more generally with post retention, post stress, root fracture, post fracture and corrosion. The most retentive posts found in dental literature, in decreasing order, are: parallel threaded (Kurer), Radix, parallel serrated (ParaPost), parallel smooth and smooth wedge-shaped posts. Stress that is produced by posts is highly dependent on post length, type of post used (tapered, parallel, serrated, etc.), type of post venting and physical properties of post (smooth-sided, sharp angles present, etc.). Root fracture depends on root length, width of preparation of pulp chamber and post selection. Post fracture depends on post diameter and type of machine manufacturing. (i.e., Rolled threads are less subjected to fracture under stresses). Finally, corrosion can occur. When a tooth is restored with a post, core and crown of different metals, corrosion products may migrate into the dentinal tubules. Some evidence links corrosion with longitudinal fracture of the root. Deutsch AS, Musikant BL, Cavallari J, Tritchler D, Lepley JB. Torque placed by dentists on prefabricated threaded posts. J Prosthet Dent 1985;53:323-325. The optimal torque value for post insertion as indicated by dentists as well as the maximum amount for torque a dentist can deliver is described. Thirty-one dentists comprised the experimental group with 37 men and 4 women ranging in age from 26 to 50 years. Only threaded self-tapping Radix posts were used in this experiment. The mean for the optimal amount of torque was 15.55 inches-onces and the mean for the maximum amount of torque was 35.19 inch-onces. Female dentists showed a statistically significant lower mean difference of 24.50 inch-onces on the maximum torque test. Deutsch AS, Musikant BL, Cavallari J, Silverstein L, Lepley J, Ohlen K, Lesser M. Root fracture during insertion of prefabricated posts related to root size. J Prosthet Dent 1985;53:786-789. Here, root size, post size, and fracture rate during insertion of prefabricated posts, was discussed. Three threaded prefabricated posts (Radix, Medidenta, and Dentatus) were randomly inserted into 212 extracted human teeth. Tapered, threaded posts increased the incidence of fracture by 20 times. When the diameter of the post was 1.5 mm, the root fracture increased sixfold for each millimeter that the diameter of the root (at the cementumenamal junction

(CEJ) decreased. The results indicate that root size and post shape are two important factors that concern root fracture during post insertion. Musikant BL, Deutsch AS. Endodontic posts and cores, part one: In vitro research. J Alabama Dent 1985;69:26-31. Review of literature clearly indicates that parallel posts are more retentive than tapered posts because they distribute functional stress more evenly. Research determine the relationship between endodontic post design, and stress produced in the roots of human teeth, has included: 1) determination of optimum torque for placing threaded posts, 2) determination of the maximum amount of torque a dentist can apply for a threaded post, 3) comparison of retention for different posts including the Flexi-Post, 4) a determination of the ideal thickness of a tapered post at the coronal portion, 5) determination of the ideal thickness a parallel post should have, at the most apical portion, and 6) determination of the amount of torque necessary, for posts of different designs, to cause root fracture during insertion. Some highlights include: 1) An average torque applied for placing threaded posts was 15.5 inc-ounces, while the maximum torque was 38 inch-ounces. 2) Retention of the Flexi-Post (120 Kg) was found to be greater than the Kurer (110 Kg), Radix (60 Kg) and Whaledent ParaPost systems (30 Kg). 3) If one mm of thickness at the coronal part of the root is reduced in thickness, this will increase the chance of vertical root fracture sixfold. Clinical Research Associates Newsletter. Posts and cores - State of the Art. 1990;14:2. This report includes descriptions and indications for various prefabricated post designs, core materials, information on popular brands of prefabricated posts, metals used for posts, and current successful concepts for prefabricated post and core placement. Prefabricated posts and cores have now become state of the art. Prefabricated posts cemented with glass ionomer, built-up with bonded composite or amalgam cores, are the most used. They compare favorably with custom posts and cores. Titanium alloy, or near pure titanium posts, are becoming the most used posts. Both the Whaledent Para-Post and Essential Dental Systems' Flexi-Post are the most used prefabricated post systems to date. Rotstein I, Karawani M, Sahar-Helft S, Mor C, and Steinberg D. Effect of NaOCl and EDTA on mercury release from dental amalgam. J Dent Res 2002;81(Abstract 1794):A-235. To assess the effect of NaOCl and EDTA on mercury release from dental amalgam in vitro using a cold-vapor atomic absorption Mercury Analyzer System. Fifty-six samples of zinc-free palladium-enriched, high-copper


dental amalgam (Valiant Ph.D.) of similar size were prepared and exposed to 10 mL solution of either 1% NaOCl, 3% NaOCl, 10% EDTA in 1% NaOCl or 10% EDTA in 3% NaOCl for periods of 20, 40 and 60 minutes. EDTA, distilled water and phosphate buffer served as controls. Mercury concentrations in solution were measured and the differences between the groups were statistically analyzed. All amalgam samples exposed to 1% NaOCl and 3% NaOCl either alone or in combination with EDTA released mercury into solution. Mercury release was significantly higher in the test groups as compared to the controls (p<0.001). Increase in the mean concentration levels of mercury in solution was time-dependent and directly related to NaOCl concentration. The addition of EDTA caused a decrease in mercury levels detected in solution. This was more significant in amalgam exposed to 1% NaOCl combined with EDTA (p<0.001). NaOCl solutions commonly used as root canal irritants may alter certain chemo-physical properties of amalgam when used as sealant for root perforation, by enhancing mercury release. Deutsch As, Cohen BI, Condos S, Musikant BL. The effect of Cold Treatment on Stainless Steel Instruments. Essential Dental Laboratories, S. Hackensack, NJ USA). J Dent Res (IADR Abstracts) 1993;72:305. The purpose of this study was to determine if cold treatment at 96 degrees celsius (using a sub-zero temperature freezer) affected the physical properties of various sizes of dental reamers and wrenches. The experiment was divided into six separate groups. Two control groups were untreated stainless steel 50 reamers and 10 wrenches. The four experimental groups were: 1 time (1 X) and 2 times (2 X) cold treatment of stainless steel 100 reamers and 20 wrenches. Each reamer was placed face-up in acrylic resin blocks and subjected to a force at a 26 degree angle, until the reamer broke. Wrenches were placed on a No. 3 Flexi-Post and torqued (measured in oz. inch), until the legs of the wrench were spread apart and the wrench slipped off the post head during torsion. The breaking force test data (measured in pounds) was obtained with a universal testing machine. Values for breaking force for reamers (Nos. 00, 0, 1, 2, and 3) were (N=10): control - 7.90, 8.30, 10.7, 21.8, 22.7 pounds; 1 X cold - 7.90, 13.1, 15.9, 25.7, 41.0 pounds and 2 X cold - 8.90, 14.9, 21.7, 23.6, 58.6 pounds. Values for wrench torsion measured with the use of a torque wrench were (N=10): control - 45.0 oz.inch; 1 X cold - 54.6 oz.inch. A two-analysis of variance (reamers) and one-analysis of variance (wrenches) (ANOVA) (p<0.05) and a Newman-Keuls multiple range comparison test was used to determine which condition (control, 1 X and 2 X) differed from one another. Reamers which were cold treated 1 X and 2 X showed increases in strength, but some sizes were not significant and some sizes benefitted due to 2 X cold treatment. Wrenches which

were cold treated 1 X and 2 X showed a significant increase in strength; however no difference was observed between 1 X and 2 X cold treatment. Hence, we conclude that cold treatment has greater potential for increasing the physical properties of stainless steel dental instruments. Cohen BI, Deutsch AS, Musikant BL. The effect of cold treatment on the physical properties of stainless steel and titanium alloy endodontic posts. J Prosthet Dent 1992;68:625-8. This study determined whether cold treatment at 96 degrees celsius affected the mechanical properties of various compositions and sizes of the Flexi-Post system. The experiment was divided into four groups of posts. The two control groups were made up of untreated stainless steel (50 posts) and titanium alloy (40 posts). The two remaining cold-treated groups were made up of stainless steel (50 posts) and titanium alloy (40 posts). In each instance the bending or breaking forces were tested on a universal testing machine. Stainless steel Flexi-Post samples showed a significant (p<0.05) increase in strength, whereas titanium alloy posts showed no significant increase in strength as a consequence of the cold treatment. 1. The cold-treated stainless steel Flexi-Post samples of all different sizes showed a significant increase in bending or breaking force compared with the untreated samples. 2. Titanium alloy Flexi-Post samples that were cold treated showed no difference in bending or breaking force compared with the untreated samples. 3. Cold treatment has great potential in dentistry for increasing the mechanical properties of stainless steel dental instruments. Goldstein GR, Hittelman E. Survey of post procedures. The New York State Dental Journal. 1992;October:32-5. Methods used to restore endodontically treated teeth have changed over the last few years. The traditional standard of using a cast-gold post and core for all endodontically treated teeth has been questioned in the literature. The following is a report of survey that the authors conducted to determine if there is a discrepancy between research and clinical practice. Clinical surveys of trained prosthodontist and highly qualified generalists are critical if one is to ascertain the current status of dental practice. Often clinical experience does not parallel laboratory findings. This survey is an example of such discrepancies. Despite laboratory evidence that tapered posts are less retentive and may cause more root fracture than parallel posts, 56 percent (58/104)of the overall population that uses cast posts, and 65 percent (13/23) of board certified prosthodontist who use cast posts still do tapered posts. It is possible that clinicians are not seeing the kind of problems in-vivo that researchers expect from in-vitro testing.


Tjan AHL, Castelnuovo J, Liu P. Bond strength of multi-step and simplified-step systems. Am J Dent 1996;9:269-272. The purpose of this paper was to measure and compare the in vitro shear bond strength (SBS) of the following three pairs of multi- and single-step dentin bonding systems: OptiBond vs. OptiBond FL, All-Bond 2 vs. One-Step, and Tenure vs. Tenure Quik. The quantity of 60 extracted human mandibular molars were sectioned perpendicular to the long axis 1 mm above the CEJ to expose the dentin bonding surface. After being wet-ground to 600 grit with SiC abrasive papers, rinsed and dried, the teeth were individually mounted in phenolic rings with epoxy resin, and randomly assigned into six equal groups of 10 each. The dentin surfaces were treated with the above mentioned dentin bonding systems, and a gelatin cylinder filled with resin composite (Pertac-Hybrid) was directly bonded to each pretreated surface. After 7-day storage in 37°C water followed bybhermocycling, the specimens were shear tested to failure on an Instron machine. Data were analyzed by independent t-test, one-way ANOVA, and Duncan’s Multiple Comparison tests at a=0.05. Except for the pair Tenure/Tenure Quik, the differences between the pairs All-Bond 2/One-Step and OptiBond/OptiBond FL were statistically significant with All-Bond 2 and OptiBond FL yielding higher shear bond strength (P<0.05). Findings of this study indicated that OptiBond FL was the only simplified-step system showing improved bond strength. Findings of this study tend to caution the clinicians that simplification of procedures does not always coincide with improvement of the performance. Sidoli GE, King PA, Setchell DJ. An in vitro evaluation of a carbon fiber-based post and core system. J Prosthet Dent 1997;78:5-9. Statement of problem: A self-contained post and core system, Composipost, comprising an epoxy-base carbon fiber post, a composite core material, and a low viscosity Bis-GMA bonding resin, has recently been marketed for the restoration of pulpless teeth. The study compared the in vitro performance and the failure characteristics of the Composipost system against existing post and core combinations. Using extracted human teeth, three post and core test groups and one control group were then tested to failure with an obliquely applied compressive load at 130 degrees in a Hounsfield testing machine with a crosshead speed of 5 cm/minute. The mean stress values at failure (MNm2) with standard deviations for each group were as follows: Composipost system 8.89, SD 2.40; stainless steel post and composite core 14.18, SD 3.49; cast gold alloy post and gold alloy core 15.25, SD 4.07; and endodontically treated tooth only 24.84, SD 4.58. The specimens restored with the Composipost

system exhibited inferior strength properties in comparison to the other post and core systems tested (p<0.01). Teeth without post and core foundations tested significantly stronger than the other comparison groups (p<0.01). Clinical Implications: A resin-bonded epoxy-based carbon fiber post system has recently been introduced for clinical use, although to date there have been few independent scientific studies to demonstrate its efficacy. This laboratory-based study demonstrated that teeth restored with a carbon fiber post system exhibited inferior strength properties in comparison to other established metallic post systems when subjected to a single angled compression load. Cohen BI, Pagnillo M, Musikant BL, Deutsch AS. Shear Bond Strength of a Titanium Reinforced Core Material Using Multi-Step vs. Single-Step Bonding Agents. J Prosthet Dent 1998;80:307-310. The purpose of this in vitro study was to evaluate the shear bond strength of a titanium reinforced core material, Ti-Core using five multi-step bonding systems (Scotchbond Multi-Purpose, OptiBond, All-Bond 2, Tenure, and Probond) and five single-step bonding systems (Single-Bond, OptiBond Solo, One-Step, Tenure Quik, and Prime & Bond 2.1). The experiment was divided into 10 groups with 10 specimens per group. The shear bond strength was evaluated after 24 hours on a MTS universal testing machine with a crosshead speed of 3.40 mm/min. The result (after an ANOVA and a Student-Newman-Keuls test) showed that All-Bond 2 (8.02 MPa) had the greatest shear bond strength (p<0.0001). All other bonding systems were not significantly different from each other. The “single-step” bonding agents did not show an improvement in shear bond strength. The wide range of shear bond strength reported for the “single-step” seems to indicate that these bonding systems are technique sensitive. Effects of three bonding systems on the torsional resistance of titanium-reinforced composite cores supported by two post designs. Cohen BI, Pagnillo MK, Newman I, Musikant BL, Deutsch AS. J Prosth Dent 1999;81(6):678-683. The resistance of an endodontic treated tooth to torsional forces is critical for the long-term survivability of the restoration. Two designs (EDS’ AccessPost and ParaPost dowels) with a core (Ti-Core, a titanium reinforced core material) utilizing four different bonding conditions (AllBond-2, ScotchBond Multi-Purpose, Tenure A & B, and without a bonding agent) resulted in eight different grouping. A total of 80 specimens were prepared and subjected to clockwise torsional forces until failure. The torsional values ranged from 53.31 inch x ounce (ParaPost/ScotchBond Multi-Purpose) to 72.31 inch x once (EDS’ AccessPost/ScotchBond Multi-Purpose). The results of the two-way of analysis of variance (two-way ANOVA) showed that there was no significant


difference between post or type of bonding system used. The use of a multi-step bonding agent had no significant effect on the torsional resistance of a core supported by a passive endodontic post. On the basis of the results of this vitro torsional study, the following conclusions were made; 1) A bonding agent has no significant effect on the torsional resistance of a post and core restoration, 2) There was no significant difference in the torsional resistance between the EDS AccessPost post system and ParaPost post system, 3) An EDS AccessPost dowel bonded with ScotchBond Multi-Purpose produced the highest torsional resistance (72.31 inch x ounce). Abdallah AI, Davidson CL. Bonding efficiency of one-bottle adhesives to contaminated dentin surfaces. J Dent Res 1998;77(Abstract #396):681. In this study the effect of water, saliva or blood contamination of a dentin substrate on the bond formation of one bottle dentin adhesives was evaluated. The one-bottle adhesives were Scotchbond 1, One Step, Prime & Bond 2.1 and Syntac SC. The three-step adhesive Scotchbond MP was used as reference. Extracted human molar teeth were used. For each tooth, enamel was removed by sectioning with a diamond saw and a smear layer was created by grinding on wet 600 grit SIC paper. Before the adhesive materials were applied and cured, the dentin was dried with air for 3 seconds and subsequently whipped with a damp cotton pellet, or contaminated with saliva, or with blood. Cylinders of the resin composite Z 100 were applied onto the adhesive dentin surfaces using a Teflon split mold. After 24 hours water storage, the shear bond strength of the specimens was determined using a tensiometer at a cross-head speed of 0.5mm/min. The morphology of the dentin-resin inter-diffusion zone was examined using SEM. Wetting of the substrated significantly increased the bond strength produced by One-step, while the bond strength of Syntac SC was significantly decreased. The bond strength produced by Scotchbond 1, Prime & Bond 2.1 and Scotchbond MP showed no significant difference. Saliva contamination decreased the bond strength significantly of only Syntac SC, while blood contamination significantly decreased the bond strength of all materials. SEM evaluation of dentin-resin interface showed a correlation between resin tag formation and bond strength. Acetone-based one-bottle adhesives performed better than water-based ones on water and saliva contaminated dentin substrates. Blood contamination, significantly reduced the bond strength of both systems. The bond strength of all one-bottle adhesives was inferior to that of the multi-step adhesive control. Efficacy of One Bottle Dentine Adhesives for Bonding Composite Resin to Dentine. Hoffman N, Sarajaljia M, Forster M, Hugo B, and Klaiber B. J Dent Res (IADR Abstract #3424) 1999;78:533.

The aim of the present study was to compare the extrusion shear bond strength of composite resin to dentine using different one bottle dentine bonding agents(DBA). Dentine slices of 2 mm height were cut from extracted from extracted human molars parallel to the occlusal surface. Cylindrical cavities of 2.3mm diameter were prepared using a drilling machine and fin grained diamond burs. In half of the samples the cavity walls were etched using 35-37% H3Po4 for 15s (E+), the remaining cavities were cleaned with 0.2% EDTA solution (Tubulicid blue, Dental Therapeutics) (E-): one group was prepared using itaconic/maleic acid as a conditioner ( No Rinse Conditioner, DeTrey) (NRC). After rinsing with water spray the samples were blotted dry on either side leaving a moist cavity surface for bonding . DBA were used according to manufactures' instructions. The cavities were filled using fine hybrid composite resin recommended by the manufacturer of the DBA or organically modified ceramics (Definite, Degussa). Following Materials were used: Etch&Prime 3.0/Definite, Degussa (E&PDef); Etch&Prime 3.0/Degufill ultra, Degussa (E&PDeg); Experimental DBA/Pertac II, ESPE (Exp); One Coat Bond/Synergy, Coltene (OCB); Onestep/AElite Fil, Bisco (OStp); Optibond Solo/Prodigy, Kerr (OptS); Prime&Bond NT/TPH Spectrum, DeTrey (P&B NT); Scotchbond One/Z100, 3M (SbO); Solobond M/Arabesk, Voco (SoloM); Syntac Sprint/Tetric Ceram, Vivadent((SynSp) After 30d of water storage (37° C) and 2500 cycles of 5-55° C bond strength was determined by pushing out the restoration using universal testing machine (/1445, Zwick) Results were statistically analyzed using pairwise U-tests with Bonferoni-Holm adjustment. Following bond strength (BS) values (MPa) values (MPa) (mean) and ranks were observed: BS/ rank P&B NTEP&Def E&PDeg Exp OCB E- 38.9/ 1 23.0/13 19.9/ 17 30.6/ 6 18.1/ 19 E+ 16.9/ 20 19.6/ 18 20.1/ 16 22.9/ 14 27.3/ 10 NRC 11.7/ 21 BS/ rank Opts OStp SbO SoloM SynSp E- 33.1/ 3 23.9/ 12 30.8/ 5 33.0/ 4 28.5/ 9 E+ 25.5/ 11 21.8/ 15 33.2/ 2 29.9/ 7 29.9/ 8 Differences between groups ranked 1-11, 5-15, 8-18 and 16-21 were not statistically significant. Prime&Bond NT gave better results without etching as compared to etching or use of NRC. With all materials bond strength was lower as compared to the best multi-bottle dentine bonding agents tested in previous studies.


Rigidity and Retention of Ceramic Root Canal Posts. Purton DG, Love RM, Chandler NP. J Dent Res 1999;78(5)[Abstract 47]:949. Any post must be sufficiently rigid and well retained in the root canal to withstand functional forces. ER-Cerapost (a ceramic post) (1.2 mm coronal diameter, ceramic, tapering, smooth posts) and Paraposts (1.25 mm stainless steel, parallel, serrated post) were tested for rigidity and for retention in roots, using a universal testing machine. The rigidity of ten posts of each type was tested by a three-point bend test. Groups of ten ceramic posts were cemented into roots using one of three cementation protocols: glass ionomer cement, silane coupling agent and resin cement, or sandblasted post surface, silane coupling agent and resin cement. Ten stainless steel posts were cemented using resin cement. The tensile force required to dislodge the posts, following 2 weeks storage in water, was recorded. Data were compared using Student’s t-tests and Mann-Whitney U analysis. The ceramic posts were more rigid than the stainless steel posts (P<0.001). The stainless steel posts (394±23N) were more strongly retained than the ceramic posts cemented with glass ionomer (54±9N) (P<0.001N), with silane and resin (118±21N) (P<0.001) and sandblasting, silane and resin (190±95N) (P<0.05N). Some sandblasted posts fractured during the retention tests. Resin cement resulted in higher retention of ceramic posts than glass ionomer cement (P<0.001). ER-Ceraposts were more rigid but less retentive than Paraposts. Sandblasting of the ceramic posts produced variable results and needs further investigation before it can be recommended. (NOTE: This study shows greater retention values for the Parapost compared to the Cerapost. In similar published research, Flexi-Post is shown to have greater retention than Parapost. Musikant BL, Cohen BI, Pagnillo MK, and Deutsch AS. Pilot Study of Torque Resistance for a Ti-Core Composite Core Using Different Bonding Agents. J Dent Res 2000;79:546 (Abstract 3221). The purpose of this in vitro experiment was to test and compare the effects of three multiple-step bonding agents (All Bond-2, Scotchbond Multi-Purpose, and Tenure A&B) and a control group (no bonding agent), on the torsional resistance of a titanium reinforced composite core material (Ti-Core). This experiment was divided into four groups with 10 specimens per group. A total of 40 recently extracted human molars were used. All crowns were removed at the cementoenamel junction (CEJ) with a diamond disk leaving a smooth, flat surface that would not hinder the core rotational movement. The teeth were then placed into acrylic blocks. All test specimens were etched according to the manufacturer’s instructions with the etching agent provided in the bonding kit. The tooth surfaces were prepared with the bonding systems according to the manufacturer’s instructions. The control group was etched with a 37.5% phosphoric acid

gel. All cores were fabricated with Ti-Core with titanium composite material using hard No. 1 copper bands as the matrix. The cores were bonded to the tooth surface with a small amount of Ti-Core material and allowed to cure for one hour before being placed into 100% humidity environment for one week. A clockwise torsional force was applied using a Lebow 1102-200 torque transducer apparatus and the loads were recorded on a Hewlett-Packard 7015B X-Y recorder in units of inch x ounces then converted in Newton x meter (Nm). A one-way analysis of variance (ANOVA) was used to compare the three bonding systems and results were considered statistically significant if p<0.05. The results were as follows; All Bond-2, 0.1980 ±0.0663 Nm; Scotchbond Multi-Purpose, 0.1890 ±0.1149 Nm; and Tenure A&B 0.2142 ±0.1021 Nm. The control group obtained a value of zero due to all specimens failing without recording a value during testing. The one-way ANOVA found no significant difference between the three bonding systems (p=0.84). All bonding systems failed as a result of adhesive failure between the bonding agent and tooth surface with no core material failures being observed. Based on the results of this pilot study, the following conclusions were made; the use of a bonding agent increases the resistance of a titanium reinforced composite core (Ti-Core) to torsional forces. There is no difference between the type of multi-step bonding systems used in this torsional study. Cohen BI, Pagnillo MK, Musikant BL, Deutsch AS, Cofrancesco G. Pilot study of the effects of three bonding systems on the torsional resistance of a titanium-reinforced composite core. J Prosthet Dent 1999;82:277-80. The purpose of this in vitro experiment was to test and compare the effects of three multiple-step bonding agents (All Bond-2, Scotchbond Multi-Purpose, and Tenure A&B) and a control group (no bonding agent), on the torsional resistance of a titanium reinforced composite core material (Ti-Core). This experiment was divided into four groups with 10 specimens per group. A total of 40 recently extracted human molars were used. All crowns were removed at the cementoenamel junction (CEJ) with a diamond disk leaving a smooth, flat surface that would not hinder the core rotational movement. The teeth were then placed into acrylic blocks. All test specimens were etched according to the manufacturer’s instructions with the etching agent provided in the bonding kit. The tooth surfaces were prepared with the bonding systems according to the manufacturer’s instructions. The control group was etched with a 37.5% phosphoric acid gel. All cores were fabricated with Ti-Core with titanium composite material using hard No. 1 copper bands as the matrix. The cores were bonded to the tooth surface with a small amount of Ti-Core material and allowed to cure for one hour before being placed into 100% humidity environment for one week. A


clockwise torsional force was applied using a Lebow 1102-200 torque transducer apparatus and the loads were recorded on a Hewlett-Packard 7015B X-Y recorder in units of inch x ounces then converted in Newton x meter (Nm). A one-way analysis of variance (ANOVA) was used to compare the three bonding systems and results were considered statistically significant if p<0.05. The results were as follows; All Bond-2, 0.1980 ±0.0663 Nm; Scotchbond Multi-Purpose, 0.1890 ±0.1149 Nm; and Tenure A&B 0.2142 ±0.1021 Nm. The control group obtained a value of zero due to all specimens failing without recording a value during testing. The one-way ANOVA found no significant difference between the three bonding systems (p=0.84). All bonding systems failed as a result of adhesive failure between the bonding agent and tooth surface with no core material failures being observed. Based on the results of this pilot study, the following conclusions were made; the use of a bonding agent increases the resistance of a titanium reinforced composite core (Ti-Core) to torsional forces. There is no difference between the type of multi-step bonding systems used in this torsional study. O’Keefe KL, Miller BH, Powers JM. In Vitro Tensile Bond Strength of Adhesive Cements to New Post Materials. Int J Prosthodont 2000;13:47-51. The purpose of this study was to measure the in vitro tensile bond strength of 3 types of adhesive resin cements to stainless steel, titanium, carbon fiber-reinforced resin, and zirconium oxide post materials. Disks of post materials were polished to 600 grit, air abraded, and ultrasonically cleaned. Zirconium oxide bonding surfaces were pretreated with hydrofluoric acid and silanated. Bis-Core, C&B Metabond, and Panavia cements were bonded to the post specimens and placed in a humidor for 24 hours. Post specimens were debonded in tension. Means and standard deviations (n=5) were analyzed by 2-way analysis of variance. Failure modes were observed. Panavia 21 provided the highest bond strengths for all types of post materials, ranging from 22 MPa (zirconium oxide) to 37 MPa (titanium). C&B Metabond bonded significantly more strongly to stainless steel (27 MPa) and titanium (22 MPa) than to zirconium oxide (7 MPa). Bis-Core results were the lowest, ranging from 16 MPa (stainless steel) to 8 MPa (zirconium oxide). In most cases, bonds to carbon fiber post materials were weaker than to stainless steel and titanium, but stronger than to zirconium oxide. In general, higher bond strengths resulted in a higher percentage of cohesive failures within the cement. Panavia 21 provided the highest bond strength to all post materials, followed by C&B Metabond. In most cases, adhesive resins had higher bond strengths to stainless steel, titanium, and carbon fiber than to zirconium oxide. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. Retentive Properties of a Split-Shank Threaded Post

with a Core Using Three Different Multi-Step Bonding Agents. Oral Health 2000;90(10):43-51. This study determined the retentive values of a Flexi-Flange post with a Ti-Core Natural core using various dental multi-step bonding agents (Tenure, All-Bond 2 and 3m Scotchbond) compared to a control where no bonding agent was used. The experiment was divided into 3 groups and a control with 10 specimens per group. The retentive strengths were evaluated after 24 hours on a 810 MTS universal testing machine with a crosshead speed of 0.638 cm/min. A one-way ANOVA illustrated that none of the groups differed statistically from each other and from the control ( P< 0.2448). The values for the retention of the Flexi-Flange/ Flexi-Flow/Ti-Core using various dentinal bonding agents ranged from a low of 264.5 pounds (Tenure) to a high of 297.9 pounds (3M Scotchbond) with a control (without bonding agent) of 270.4 pounds. All of the retention for the Flexi-Flange post resulted from the retention of the split-shank threaded portion (mechanical retention) of the post which mechanically engages the root canal. The phenomenon where mechanical retention is greater and more significant than chemical retention ( from dentinal bonding agents) has been described previously in the literature. Deutsch AS, Cohen BI, Musikant BL. Inductively Coupled Plasma-Emission Spectroscopy and Atomic Absorption for the use of Elemental Analysis of a Root Canal after Lasing with a Holmium:YAG Laser. J Endodon 2003;29(6):404-406. It has been reported in the literature that after lasing dentin, the dentin surface has a glassy or globular appearance. Many authors believe this to be recrystallized hydroxyapatite. The aim of this elemental analysis was to see if any of the silica fiber optic was melted and deposited as these globular structures on the canal wall. Two teeth were used. One was hand instrumented with files and used as the control, the other was lased with a Ho:YAG laser. A 245 micron low OH- fiber was used. The roots were micro-analyzed for oxygen, phosphorus, silicon, nitrogen, hydrogen , calcium and carbon. The percentages for all elements tested were in the same range for both teeth. Therefore, there was no silicon deposited onto the canal wall of the tooth that was lased. It is concluded that the low OH- silica fiber optic was not melted and deposited onto the dentinal canal wall. Deutsch AS, Cohen BI, Musikant BL. Temperature Change at the Root Surface, When Enlarging a Root Canal with a Holmium YAG (Ho:YAG) Laser, Using Six Different Fiber Optic Sizes. Gen Dent 2003 Submitted. The aim of this in vitro study is to determine if there is an increase in the change in temperature (_T) at the root surface as the canal is enlarged with a Ho:YAG laser (using six different sized fiber optic tips). Ninety single rooted human teeth were randomly assigned to one of


three groups according to laser power settings; 0.50 W, 0.75 W and 1.00 W. Each tooth in each power group was subjected to lasing using fiber sizes of 140, 200, 245, 300, 355, and 410 microns. The dependent variables in these analyses included; a) change in temperature, (measured with T-type thermocouples placed 2mm from the coronal and apical ends of the root). b) depth of the tooth during lasing, c) depth of the tooth using conventional files, and e) tooth measurements. RMANOVA for coronal temperature showed no interaction between fibers and power settings was observed. RMANOVA for apical temperature showed a significant difference between fibers but not between power settings. For the depth of tooth during lasing (how far the fiber optic guide penetrated into the tooth) no interaction between fibers and power settings was observed. Pairwise contrasts revealed that all fibers were different from one another, with depth decreasing as fiber size increased. For tooth measurements, ANOVA illustrated that there was no significant differences between power settings for any of the five tooth measurements. All temperature differences observed apically and coronally were between 0° to 11°celsius, with the majority being (greater than 95%) less than 5°celsius. After lasing with the 410 micron fiber, the root canals were sufficiently widened to at least 45 or 50 K files (450 or 500 microns). Deutsch AS, Cohen BI, Musikant BL. Duration of Temperature Change at the Root Surface, When Enlarging a Root Canal with a Holmium YAG (Ho:YAG) Laser, Using Six Different Fiber Optic Sizes. Oral Health 2003 Submitted. The aim of this in vitro study was to determine if there was an increase in the duration of heat retention (_ D) at the root surface as the canal was enlarged with a Ho:YAG laser (using six different sized fiber optic tips). Thirty single rooted human teeth were randomly assigned to one of three groups according to laser power settings: 0.50 W, 0.75 W and 1.00 W. Each tooth in each power group was subjected to lasing using fiber sizes of 140, 200, 245, 300, 355, and 410 microns. Thermocouples were connected to a programmable chart recorder (RD 102,Omega) which also gave the duration of heat retention (_D) for each coronal and apical measurement. _ D difference was calculated by a ratio of the known chart speed (12000mm per hour) and distance for the temperature delta difference (duration of heat retention _D ) for apical and coronal measurements. The dependent variables in these analyses included: (a) change in temperature (_T), (b) duration of heat retention (_ D, i.e., time from lasing until return to initial temperature), (c) depth of the tooth during lasing, (d) depth of the tooth using conventional files, and (e) tooth measurements. The means for _D ranged from 10 seconds to 60 seconds. Both Coronal and Apical _D means differed statistically significantly according to fiber size and power setting.

Correlation coefficients (r) showed that for each fiber size both for coronal and apical there was a moderate and moderate to strong significant correlation between temperature change _T and Duration _D. Deutsch AS, Cohen BI, Musikant BL. Use of HO:YAG Laser with Multiple Fibers to Enlarge a Root Canal. J Dent Res 82 (Special Issue B (Goteborg Abstracts)):Abstract #2670,2003. Objective: This in vitro experiment determined if there is an increase in the change in temperature (delta T) at the root surface (using multiple fiber optic guides 140µ, 200µ, 245µ, 300µ, 355µ and 410µ ) as a root canal is enlarged when using a HO:YAG laser. Methods: 90 recently extracted single rooted human teeth were assigned; Group 1, power setting of 0.5W ; Group 2, 0.75 W and Group 3, 1.00 W. T-type thermocouplers (Omega) were placed approximately 2 mm from the coronal and apical sites. The specimens in each of the three groups were subjected to lasing using fiber optic sizes of 140µ, 200µ, 245µ, 300µ, 355µ and finally 410µ. Statistical analysis was performed (RMANOVA, Student-Newman-Keuls (SNK) multiple comparisons test, and a Bonferroni correction was used to check for significance) and the dependent variables were: a) change in temperature (delta T) at the coronal and apical site, b) depth of tooth during lasing, c) depth of tooth using conventional files and d) tooth measurements. Results: RMANOVA for coronal temperature showed no significant difference between fibers and power settings and for apical temperature there was a significant difference between fibers and power settings. For the depth of tooth during lasing, a significant difference between fibers was observed. Pairwise contrasts revealed that fibers 140µ and 200µ were not different from one another and that fiber after 245µ were different from one another. In general, it was observed that the depth decreased as fiber size increased. Conclusions: All temperature differences observed apically and coronally were between 0° to 11°C. After lasing with the 410µ fiber, the root canals were sufficiently widened to at least a 45 K file. The results illustrate that lasing a root canal with a HO:YAG laser could be an efficient alternative to mechanical enlarging. Deutsch AS, Cohen BI, Musikant BL. Temperature change at the root surface when enlarging a root canal with a holmium:YAG(Ho:Yag) laser, using six different fiber-optic sizes. 2004 May-June General Dentistry. This in vitro study was designed to determine if enlarging a canal with a holmium:YAG(Ho:YAG) laser (using six different-sized fiber-optic tips) would increase the change in temperature at root surface and if fiber-optic tips spaced more closely would enlarge the canal more efficiently and consistently.


Gu S, Rasimick BJ, Deutsch AS, Musikant BL. Radiopacity of dental materials using a digital x-ray system. Dental Materials 2006;22:765-770. Objectives. Radiopacity is desirable property for most intra-oral materials. There are established ISO and ANSI/ADA protocols for determining radiopacity using film-based radiography. However, these methods are not always followed by researchers. This study aims to adapt those procedures by using digital radiography, a simplified stepwedge, and examine the effects of target distance and exposure time choice. Methods. One milimetre thick samples of three dental materials were prepared by placing the materials into a 1.00mm thick washer sandwiched between two glass slides. The samples were digitally radiographed alongside a stepwedge of aluminum alloy 1100 with an x-ray unit at 70kVp using five different target distanc/exposure time combinations. For each combination, the grey scale values of various thicknesses of the stepwedge were converted into absorbencies and plotted against their thickness. These plots were then linearly regressed in order to correlate absorbance with a thickness of aluminum for each target distance/exposure time combination. The absorbencies of each sample were then converted into radiopacities using these correlations. Results. The correlations between the absorbance of the stepwedge and its thickness were highly linear. This linearity allows the correlation to be accurately deduced from fewer data points than required by the ISO and ANSI/ADA protocols. Varying exposure time did not significantly affect the mean radiopacity measured at a target distance of 30 cm. Varying the target distance did not significantly affect the measured radiopacity as long as the samples were properly exposed. Signifiance. A simplified, consistent digital method for determining radiopacity is presented.

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