ultrasonics in endodontics - a review of literature

7/30/2019 Ultrasonics In Endodontics - A Review of Literature

1/15

Ultrasonics in Endodontics: A Review of the LiteratureGianluca Plotino, DDS,* Cornelis H. Pameijer, DMD, DSc, PhD, Nicola Maria Grande, DDS,*and Francesco Somma, MD, DDS*

Abstract

During the past few decades endodontic treatment hasbenefited from the development of new techniques andequipment, which have improved outcome and predict-ability. Important attributes such as the operating mi-croscope and ultrasonics (US) have found indispensableapplications in a number of dental procedures in peri-odontology, to a much lesser extent in restorative den-tistry, while being very prominently used in endodon-tics. US in endodontics has enhanced the quality oftreatment and represents an important adjunct in thetreatment of difficult cases. Since its introduction, US

has become increasingly more useful in applicationssuch as gaining access to canal openings, cleaning andshaping, obturation of root canals, removal of intraca-nal materials and obstructions, and endodontic surgery.This comprehensive review of the literature aims atpresenting the numerous uses of US in clinical endo-dontics and emphasizes the broad applications in amodern-day endodontic practice. (J Endod 2007;33:8195)

Key Words

Endodontics, innovations, ultrasonics

The use of ultrasonics (US) or ultrasonic instrumentation was first introduced todentistry for cavity preparations (13) using an abrasive slurry. Although the tech-nique received favorable reviews (4, 5), it never became popular, because it had tocompete with the much more effective and convenient high-speed handpiece (6).However, a different application was introduced in 1955, when Zinner (7) reported onthe use of an ultrasonic instrument to remove deposits from the tooth surface. This wasimproved upon by Johnson and Wilson (8), and the ultrasonic scaler became anestablished tool in the removal of dental calculus and plaque. The concept of using USin endodontics was first introduced by Richman (9) in 1957. However, it was not untilMartin et al. (1012) demonstrated the ability of ultrasonically activated K-type files tocut dentin that this application found common use in the preparation of root canals

before filling and obturation. The term endosonics was coined by Martin and Cunning-ham (13, 14) and was defined as the ultrasonic and synergistic system of root canalinstrumentation and disinfection.

Ultrasound is sound energy with a frequency above the range of human hearing,which is 20 kHz. The range of frequencies employed in the original ultrasonic units wasbetween 25 and 40 kHz (15). Subsequently the so-called low-frequency ultrasonichandpieces operating from 1 to 8 kHz were developed (1621), which produce lowershear stresses (22), thus causing less alteration to the tooth surface (23).

There are two basic methods of producing ultrasound (2426). The first is mag-netostriction, which converts electromagnetic energyinto mechanicalenergy. A stack ofmagnetostrictive metal strips in a handpiece is subjected to a standing and alternatingmagnetic field, as a result of which vibrations are produced. The second method isbased on the piezoelectric principle, in which a crystal is used that changes dimensionwhen an electrical charge is applied. Deformation of this crystal is converted intomechanical oscillation without producing heat (15).

Piezoelectric units havesomeadvantages comparedwithearlier magnetostrictiveunitsbecause they offer more cycles persecond, 40 versus 24 kHz. Thetips of these units work inalinear,back-and-forth,piston-likemotion,whichisidealforendodontics.Leaetal.( 27)demonstrated that the position of nodes and antinodes of an unconstrained and unloadedendosonicfileactivated bya 30-kHzpiezon generator wasalong thefilelength. Asa resultthefile vibration displacement amplitude does not increase linearly with increasing generatorpower. This applies in particular when troughing for hidden canals or when removingposts and separated instruments. In addition, this motion is ideal in surgical endodonticswhen creating a preparation for a retrograde filling. A magnetostrictive unit, on the otherhand, creates more of a figure eight (elliptical)motion, which is not ideal foreither surgicalornonsurgicalendodonticuse.Themagnetostrictiveunitsalsohavethedisadvantagethatthestack generates heat, thus requiring adequate cooling (15).

Applications of US in EndodonticsAlthough US is used in dentistry for therapeutic and diagnostic applications as well

as for cleaning of instruments before sterilization (28), currently its main use is forscaling and root planing of teeth and in root canal therapy (15, 28, 29). The concept ofminimally invasive dentistry (30, 31) and the desire for preparations with smalldimen-sions has stimulated new approaches in cavity design and tooth-cutting concepts, in-cluding ultrasound for cavity preparation (32).

ThefollowingisalistofthemostfrequentapplicationsofUSinendodontics,whichwill be reviewed in detail:

1. Access refinement, finding calcified canals, and removal of attached pulpstones

From the *Department of Endodontics, Catholic Universityof Sacred Heart, Rome, Italy; and the School of Dental Med-icine, University of Connecticut, Farmington, CT.

Address requests for reprints to Gianluca Plotino, DDS, ViaEleonora Duse, 2200197 Rome, Italy. E-mail address:[email protected]/$0 - see front matter

Copyright 2007 by the American Association ofEndodontists.doi:10.1016/j.joen.2006.10.008

Review Article

JOE Volume 33, Number 2, February 2007 Ultrasonics in Endodontics 81


2/15

2. Removal of intracanal obstructions (separated instruments, rootcanal posts, silver points, and fractured metallic posts)

3. Increased action of irrigating solutions4. Ultrasonic condensation of gutta-percha5. Placement of mineral trioxide aggregate (MTA)6. Surgical endodontics: Root-end cavity preparation and refine-

ment and placement of root-end obturation material7. Root canal preparation

Access Refinement, Finding Calcified Canals, and Removal ofAttached Pulp Stones

One of the challenges in endodontics is to locate canals, particu-larly in cases in which the orifice has become occluded by secondarydentin or calcified dentin secondary to the placement of restorativematerials or pulpotomies. With every access preparation in a calcifiedtooth, there is the risk of perforating the root or, when incorrectlyperformed, of complicating each subsequent procedure. A lack of astraight-line access is arguably the leading cause of separation,perforation, and the inability to negotiate files to the radiographicterminus (33).

Theintroduction of themicroscope,access burs, and US (34)hasgreatly reduced these risks. Microscopic visualization and ultrasonic

instruments are a safe and effective combination to achieve optimalresults (3537).

In difficult-to-treat teeth such as molars, US hasprovento be usefulfor accesspreparation, not onlyfor findingcanals, but also for reducingthe time and the predictability of the treatment (33, 34).

In conventional access procedures, ultrasonic tips are useful foraccess refinement, location of MB2 canals in upper molars and acces-sory canals in other teeth, location of calcified canals in any tooth, andremoval of attached pulp stones (3537).

There are numerous variations of rotary access burs available;however, one of the more important advantages of ultrasonic tips is thatthey do not rotate, thus enhancing safety and control, while maintaininga high cutting efficiency. This is especially important when the risk of

perforation is high.The visual access and superior control that ultrasonic cutting tips

provide during access procedures make them a most convenient tool,especially when treating difficult molars. When locating the MB2 canalsin upper molars, US is an excellent means for the removal of secondarydentin on the mesial wall (Fig. 1). When searching for hidden canals,one should remember that secondary dentin is generally whitish oropaque, whereas the floor of the pulp chamber is darker and gray inappearance. US works well when breaking through the calcification thatcovers the canal orifice. A troughing tip is a good choice for this task(Fig. 2a,b). For these applications, bigger tips with a limited diamond-coated extension should be used during the initial phase of removingcalcification, interferences, materials, and secondary dentin, as they

offer maximum cutting efficiency and enhance control while working inthe pulp chamber (Fig. 2c,d). The subsequent phase of finding canalorifices should be carried out with thinner and longer tips that facilitateworking in deeper areas while maintaining clear vision (33, 34) (Fig. 2e).

The diamond-coated tips used in orthograde endodontic treat-ment (Fig. 2a e) have shown significantly greater cutting efficiencythaneitherstainless steel tips or zirconium nitridecoated tips, but theyhave a tendency to break (38). Moreover, thinner diamond-coated tipsseem to be able to transmit the oscillation of the ultrasonic unit moreefficiently into dentin; this results in a more aggressive cutting action(39). Ultrasonic cutting seems to be significantly influenced by thepower setting (39), as larger fragments of dentin are removed at higherpower (40), and by the ultrasonic unit type used (39). Therefore, careshould be exercised while searching for canal orifices, as aggressive

cuttingmay cause an undesired modification of the anatomy of thepulpchamber.

Removal of Intracanal Obstructions

Clinicians are frequently challenged by endodontically treatedteeth that have obstructions such as hard impenetrable pastes, sepa-rated instruments, silver points, or posts in their roots ( 41). If end-odontic treatment has failed, these obstructions need to be removed toperform nonsurgical retreatment. Many instruments and techniqueshave been reported (42, 43). They include appropriate burs (44);special forceps (45); ultrasonic instruments in direct or indirect con-tact (4649); peripheral filing techniques in the presence of solvents,chelators, or irrigants (50); microtube delivery using mechanical ad-hesion techniques (51); and different kits and extractors (5254).

Ultrasonic energyhas proven effective as an adjunctin the removalof silver points, fractured instruments, and cemented posts (55). It has

Figure 1. The orifice of the second mesiobuccal canal (MB2) in an upper firstmolar was located (a) and enlarged (b). Dentine spur at the orifice was effec-tively eliminated withthe use of a diamond-coatedultrasonic tip,thus permittingeasy location of the orifice of the canal.

Review Article

82 Plotino et al. JOE Volume 33, Number 2, February 2007


3/15

oftenbeenadvocatedfortheremovalofbrokeninstrumentsbecausetheultrasonic tips or endosonic files may be used deep in the root canalsystem(56). Furthermore, the use of an ultrasonic endodontic device isnot restricted by the position of the fragment in the root canal or thetooth involved (57).

The prognosis of these cases mainly depends on the preoperativecondition of the periapical tissues (58, 59). For this reason an attempttoremovebrokeninstrumentsshouldbeundertakenineverycase(60).When these obstructions can be removed, successful treatment or re-

treatment generally occurs (61). If an instrument can be removed orbypassed and the canal can be properly cleaned and filled, nonsurgicalendodontics is a more desirable and conservative approach (62). Theremoval of an obstacle from a root canal must be performed with aminimum of damage to thetooth andthe surrounding tissues (44).Toomuch destruction of tooth structure will complicate the restorativephase and as a result will most likely decrease the overall prognosis.

Although it is possible to remove many fragments, a small numbercannot be removed because of limited access, despite the use of ultra-sonictips(63) (Fig.2f,g).Whentheobstaclepreventsaccesstotherootapex, adequate preparation, disinfection, and obturation of the entireroot canal system are not possible. Straight-line access is essential andallows for maximum visibility of the metallic fragment (64). For that

reason, the use of magnification (dental operating microscope orloupes) is essential, as it provides direct visualization with excellentillumination, allowing instrumentation at high magnifications.

Separated Instruments

Management of a broken instrument requires an orthograde or asurgical approach. The three orthograde approaches are (a) attempt toremove the instrument; (b) attempt to bypass the instrument; and (c)prepare and obturate to the fractured segment (65).

In most cases, removal of broken instruments from the root canalis difficult and often hopeless (66). To date, no standardized procedurefor the safe removal of fractured instruments exists, although varioustechniques and devices have been suggested(67,68). These techniqueshave shown onlylimited success, while often causing considerabledam-

age to the remaining root (61, 68). Complications as a result of thesetechniques include excessive loss of root canal dentin, ledging, perfo-ration, and extrusion of the fractured instrument fragment through theapex (69). Therefore, many techniques cannot be used in narrow andcurved canals (61).

Over the years, different techniques have been proposed for theremoval of separated instruments from root canals (44, 57, 60, 63, 66,7072). Recent advances in endodontics have led to the developmentof techniques and devices designed specifically for the safe removal of

fracturedinstruments from deep within narrowcurvedroot canals (73)(Fig. 3). Ruddle (64, 71) proposed a technique for the removal ofbroken instruments using Gates Glidden drills (size 3 or 4) to preparea circumferential staging platform at the coronal aspect of the ob-struction(Fig.4).Attentionmustbepaidduringpreparationofastagingplatform, because a size 3 or 4 Gates Glidden may perforate or weakena root, for instance the mesial (74, 75) and distal root (76) of mandib-ular molars, the distobuccal and mesiobuccal roots of maxillary molars(77),andcentralandlateralmandibularincisors(77).Theiruseseemssafe in central and lateral maxillary incisors (77), maxillary and man-dibular canines (77), and mandibular premolars (78, 79). The litera-ture is controversial with regardto maxillarypremolarsbecause of theirparticular anatomy (8082).

Radiographic evaluation of the residual dentin thickness duringpreparation of the platform can be misleading because of the inaccu-racy of radiographic interpretation. Overestimation may lead to over-preparation of the canal or root perforation (83). Recently, it has beenshown that preparation of staging platforms wasbest accomplished withthe use of modified LightSpeed files (84). The inability to see theinstru-ment with direct vision and the difficulty of creating a staging platform,as well as the use of US in curved roots, has contributed to a lack ofsuccess in removing fractured instruments under these circumstances(57, 61, 63, 69, 84).

Root Canal Posts

Nonsurgicalendodontic retreatmentof teeth restored with intrara-dicular posts continues to present a challenge because of the inherent

Figure2. (a) TheBUC-1is an example of diamond-coated spreader tip of mediumlength that canbe used forgrossdentin removal, movingaccess line angles, cuttinga groove in the mesial access wall to drop into MB2 canals, and quickly and carefully unroofing pulp chambers. (b) The BUC-3 is similar to the BUC-1 with a sharpertip and a water port for increased washing and cooling of the operative site. It is used for chasing canals or for digging around a post or carrier-based obturator withthe objective to remove it. (c) This diamond-coated pear tip is used to find canals, remove coronal obstructions or restorative materials, or remove calcifications,temporaryand permanentcements,and posts.It creates a smooth, clean flat troughinggroove that facilitatescanallocation. (d) Thisdiamond-coatedball tipprovidesfine cutting control when preparinga troughinggroove andis less aggressive than thepear tipshown in c,yetithasthesameclinicalindications.(e) A classic spreadertip with a diamond coating, which offers a side- as well as an end-cutting action. This is needed to flare the walls of a troughing groove in an axial direction. (f) A fine

spreader tip indicated for troughing and removal of broken instruments. (g) An extra-fine spreader tip used for extremely fine and deep troughing or removal of aseparated instrument in the middle or apical third of the canal. (h) A spreader tip designed for multiple uses such as instrument or silver point removal, troughing,removal of calcifications, provisionals, cements, buildup materials, etc. (i) Vibrator tip specifically designed for post removal.

Review Article



4/15

difficulties of removing posts without weakening, perforating, or frac-turing the remaining root structure (8588). Many techniques andinstruments have been described to aid in the removal of posts (52, 85,8894).

US has provided clinicians with a useful adjunct to facilitatepost removal with minimal loss of tooth structure and root damage(48, 9597). Many studies have focused on the removal of metallicposts; however, retreatment of fiber-reinforced composite posts ce-mented with adhesive systems presents a new challenge in cases inwhich endodontic treatment has failed (98). Different bur kits havebeen proposed to remove fiber posts (99, 100); however, the preser-vation of maximum root structure requires the use of specific ultrasonic

Figure 4. Gates Glidden bur modified by cutting it at the maximum diameterviewed from an apical (a) and lateral direction (b). This permits the prepara-tion of a platform at the extruded portion of the fragment to be removed.

Figure 3. NiTi rotary instrument separated in the distobuccal canal of an upperfirst molar (a). The fragment was removed using ultrasonic tips, and the rootcanals were successfully negotiated to the apex (b) and cleaned, shaped, andfilled (c). The tooth was subsequently restored with two fiber-reinforced posts,one in the palatal and one in the mesiobuccal canal, followed by a dual-cureresin composite core buildup (c).

Review Article



5/15

tips (Fig. 2h) and adequate magnification. The disruption of the com-posite structure through the action of ultrasonic vibration seems to bethe most effective technique in fiber post removal (101). Esthetic whiteposts are more difficult to remove because their color matches that ofdentin, whereas the black carbon fiber posts clearly contrast to dentin.Removal is done in a dry field using a continuous stream of air withdirect vision of the ultrasonic tip and the coronal portion of the post,alternated by air and water spray to clean the remnants of fibers anddentin.

It is important that the entire composite material that was used inthe luting procedure be removed. If the adhesive procedure was donewell, removal of the tenaciously attached adhesive materials will bedifficult, and highmagnificationmust be used to guide the ultrasonictipto selectively remove the attached composite material. If the ultrasonictipleaves behind gray streaks, it is a clear indicationthat resin compos-ite or resin composite cement is still present.

The need of consuming fiber posts is based on the fact that theviscoelastic nature of composite resin dampens vibrations and adsorbsenergy (102). Conductance of vibration forces within a post is propor-tional to the square root of the modulus of elasticity of the post material(103). Therefore, a fiber-reinforced composite post with a significantlylower modulus of elasticity than stainless steel or titanium (104, 105)

conducts vibration less efficiently (97). Combining the low modulus ofelasticity of post materials with composite resin cements causes achange in the effectiveness of US as an aid in post removal ( 97). Resincements are not friable and do not tend to produce microfractures dueto ultrasonic vibration (106). It was suggested that the absence of awater spray seems to increase the action of US when applied to postscemented with resin cements, possibly because of the increase in heat(107). This is helpful information, as it has been observed that thecapacity of adhesion of a resin cement, and consequently mechanicalretention, gradually reduces with the number of thermal cycles (108).

Several studies point to the fact that ultrasonic vibration of postsfacilitates their removal while conserving tooth structure and reducingthe possibility of fractures or root perforations (55, 86 88, 95, 102,

109). Several studies have demonstrated a reduction in tensile failureloads of intraradicular-cemented posts after ultrasonic vibration (55,8688,95,102,107,109116).Otherstudiesdidnotfindadifference

(97, 117, 118). Bergeron et al. (119) and Garrido et al. (107) sug-gested that heat generation might have been responsiblefor the increasein retention after ultrasonic vibration, as no water-cooling was usedduring the procedure. As to the fiber-reinforced root canal posts,Bergeron et al. (119) and Hauman et al. (97) further hypothesized thatthe lower modulus of elasticity of the titanium compared with that of thestainless steel may have been responsible for the ineffectiveness of US inreducing post retention.

Using US involves the initial removal of restorative material(s) andluting cement around the post, followed by application of the tip of anultrasonic instrument to the post (Fig. 5a g). Ultrasonic energy istransferred through the post and breaks down the cement until the postloosens (107) (Fig.5h). This method of post removal minimizes loss oftooth structure and decreases the risk of tooth damage (48, 95, 97).

When removing a post, it is critical to break the seal between thepost and the tooth structure. It has been recommended to reduce theextraradicular portion of the post to the same diameter as the intrara-dicular portion (118) to reduce the necessary tension to remove it(114). In some cases this can be accomplished with a surgical-lengthround bur, a technique not withoutdanger. Once trephining around thepost has been done, a basic spreader tip placed in the trough is a good

choice(Fig.2h).Thiswillfurtherbreakdowntheintegrityofthecementor resin, usually resulting in loosening of the post. Alternatively, theultrasonictipcanbeplacedonthepostoronahemostatthatisclampedto the post. The tip should not be too thin, because small-diameterultrasonic instruments are weak and more predisposed to breakage,especiallywhentheyareusedforalongtimeonaresistantmaterial( Fig.2i). On the other hand, the tip should not be too large, because it mustbe kept in intimate contact with thepostwhen it is moved counterclock-wise around the post (98) (Fig. 2a,b). Usually, the ultrasonic unit is setto the maximum power level (97, 107, 111, 114, 119, 120). Becausethis generates heat, especially over longer periods of application, cool-ing with a water spray is of the essence. When heat is transferred to ametal post, it can be transferred to the periodontal ligament, causing

damage (121), even with the useof a piezoelectric ultrasonic handpiece(122). There is in vitro evidence that application of US to metal posts,even with adequate water-spray cooling (120), can lead to rapid in-

Figure5. Preoperative image(a) andradiograph (b) of a mandibular first molar with three gold castpostsand cores andfull-crown coverage.The patient presentedwith pain and swelling. The preoperative diagnostic radiograph revealed signs of radiolucency in the furcal area toward the mesial root. The metal-ceramic crownwas sectioned (c) and removed (d), and the gold cast posts were separated to facilitate their removal (e, f). The three posts were removed (g) by vibrating with anultrasonic tip to disrupt the cement seal (h). This clinical image revealed two perforations in the mesial root canal (h). Perforations were repaired using gray MTAcompacted with an ultrasonic tip (i). Root canals were filled with gutta-percha and sealer (l), and the coronal portions of the mesial canals were further filled withMTA to enhance the seal of the perforations (m). Postendodontic preprosthetic restoration was performed using a fiber-reinforced post in the distal canal and adual-cure resin composite buildup material (n).

Review Article



6/15

creases in temperature of the root surface, causing damage to the peri-odontal ligament (122, 123).

The relative ease of removing prefabricated parallel posts with theuse of US is probably related to their design, as they do not adapt well tothecoronalthird of most root canals. This allows for easy breakdown ofthe cement in the coronal third and subsequent shifting of the fulcrumpoint toward the apical end of the post. As the fulcrum point shiftsapically, the ultrasonic vibrations start to move the post about this point

and within the space created in the coronal third. This movement helpsto break down the cement/post interface toward the apical end of thepost in conjunction with breakdown within the cement itself.

In cases in which the post has a tight fit with adequate length anddiameter, and with limited accessto the coronalportion, the effect of USalone may be limited or even ineffective. In these situations the clinicianhas to consider other treatment options (118).

In a clinical study by Smith (112), the mean time required todislodge posts with an ultrasonic instrument was approximately one-quarter of that reported for in vitro studies (97). This may be explainedin that, in a clinical setting, the reason for removing posts is due toinfected root canals frequently caused by coronal leakage, leading tobreakdown of the cement, retaining both the coronal restoration andthe post. In clinical practice posts should therefore be easier to removethan under laboratory conditions (97). Clinically, after removing allcircumferential restorative materials, the majority of posts can be safelyand successfully removed within approximately 10 minutes(102,110).However, certain posts resist removal, even after 10 minutes of ultra-sonic activation (98).

Silver Points and Fractured Metallic Posts

Several studies have shown that retrieval of silver cones can beperformed with traditional techniques using hand instruments and par-ticular devices and extractors (45, 50, 51, 66, 124, 125).

Other techniques utilize ultrasonic energy in cases of intracanalobstruction and consume the obstruction with particular ultrasonic

tips. This predominantly applies to silver points inside canals, whichcannot be bypassed by conventional methods (62, 126).The traditional clinical procedure to remove root canal posts or

silverpointsfracturedattheorificeconsistsofexposingthecoronalpartof the obstacle by cutting an estimated 2.0-mm trough around the ob-stacle with a fine diamond bur. The tip of an ultrasonic unit (Fig. 2h) isthen applied to the side of the post fragment at full power with waterirrigation. Ultrasonic vibration is applied for periods of a few secondsfollowed by drying with compressed air. This should lead to dislodge-ment of the fragment ofthe post, which can then be removed with a fineforceps (47, 112, 127).

When an obstruction allows for limited access to the coronal por-tion of the point, a more conservative approach would be to try to

consume it instead of consuming the surrounding dentin (62, 126).An important point to realize when removing silver points is thatone is dealing with a very soft material. Any misdirection of a bur cansever the point, complicating the case even further. US has proven to bevery helpful in the removal of these points. Simply trough around thesilver point with an ultrasonic spreader tip (Fig. 2f,g) and carefullyeliminate dentin while following the long axis, taking care not to cut thepoint. The space created around the silver point will usually loosen thesilver point, which can then be removed with a Steiglitz forceps orhemostat. At all times, the use of intraoral radiographs is recommendedto confirm the position and the remaining length of the obstruction, aswell as the thickness of canal walls (47, 64). The time required forremoval of a post or silver point is influenced by the nature of theobstruction, its diameter, and location. Semiprecious metals take more

time than precious metals. Large-diameter posts are more time con-suming compared with narrow ones (62).

Increased Action of Irrigating Solutions

The effectiveness of irrigation relies on both the mechanicalflushing action and the chemical ability of irrigants to dissolve tissue(128, 129). Furthermore, the flushing action of irrigants helps to re-move organic and dentinal debris and microorganisms from the canal(130). The flushing action from syringe irrigation is relatively weak anddependent not only on the anatomy of the root canal but also on thedepth of placement and the diameter of the needle (128, 131, 132). Ithas been shown that irrigants can only progress 1 mm beyond the tip ofthe needle (133). An increase in volume does not significantly improvetheir flushing action and efficacy in removing debris (134, 135). Inlarger apical canals, the debridement and disinfection of canals is im-proved (128). However, thorough cleaning of the most apical part ofany preparation remains difficult (136). Using thinner needles (30gauge) may facilitate reaching the apical area directly. Although con-clusive evidence is still lacking, the introduction of slim irrigating nee-dles with a safety tip placed to working length or 1 mm short of it is apromising approach to improve irrigant efficacy.

The only effective way to clean webs and fins is through movement

of the irrigation solution (137), as they cannot be mechanically cleaned(138). US is a useful adjunct in cleaning these difficult anatomicalfeatures. It has been demonstrated that an irrigant in conjunction withultrasonic vibration, which generates a continuous movement of theirrigant,isdirectlyassociatedwiththeeffectivenessofthecleaningoftheroot canal space (22, 137142).

Acoustic streaming, as described by Ahmad et al. (140), has beenshown to produce sufficient shear forces to dislodge debris in instru-mented canals. When files were activated with ultrasonic energy in apassive manner, acoustic streaming was sufficient to produce signifi-cantly cleaner canals compared with hand filing alone. Similarly,Jensen et al. (143) recommended a vibrating fileof small size subjectedto a high power setting, as smaller files will be less likely to contact the

canal walls.The flushing action of irrigants may be enhanced by using US ( 15,

132, 140, 144, 145). This seems to improve the efficacy of irrigationsolutions in removing organic and inorganic debris from root canalwalls (12,129,132,142,143,145158 ).Apossibleexplanationfortheimproved action is that a much higher velocity and volume of irrigantflow is created in the canal during ultrasonic irrigation (129).

The tissue-dissolving capability of solutions with a good wettingability may be enhanced by US if the pulp tissue remnants and/or smearlayer are wetted completely by the solution and become subject to theultrasonic agitation (145, 159). US creates both cavitation and acousticstreaming. The cavitation is minimal and is restrictedto the tip (160).Theacoustic streaming effect, however, is significant (161). In fact, the irrigant

is activated by the ultrasonic energy imparted from the energized instru-ments, producing acoustic streaming and eddies (15, 140, 141).UScanalso improvedisinfectionof root canals(148,149,162166),

probably because organic tissues entering the streaming field that isgenerated are disrupted, as proposed by Walmsley (24). Ahmad (167)confirmed that ultrasonically activated files produced streaming pat-terns close to the file, continuously moving irrigants around, therebyproducing shear stress, which can damage biological cells, as stated byWilliams (168).

Although the number of surviving colonies was less when ultra-sonic activation was used, no technique was able to ensure completedisinfection (130, 143, 161, 169, 170). Cameron (171) postulated thatthere is a synergistic effect between sodium hypochlorite (NaOCl) andUS. The ability of NaOCl to dissolve collagen is enhanced with heat

Review Article



7/15

(172); therefore, the effect of heat on the irrigant produced by ultra-sonic action plays an important role (15, 173).

The effectiveness of hand syringe irrigation in narrow canals hasbeen questioned by several investigators (145, 174178). Narrow ca-nals may also compromise the effectiveness of ultrasonic irrigation(15, 144, 179), and when sonic or ultrasonic files are used in small,curved canals, they maybind, thusrestricting their vibratorymotionandcleaning efficiency (180).

For irrigating solutions to be effective, they have to be in directcontact with a surface (181). In small-diameter roots, irrigating solu-tionshavedifficultyreachingtheapexofthetoothandthereforeareleastinfluenced by activated irrigation (166, 182). Furthermore, van derSluis et al. (183) have postulated that ultrasonic irrigation should bemore effective in removing debris from root canals with greater tapers.It appeared to be important to apply the ultrasonic instrument aftercanal preparation had been completed (184). Furthermore, a freelyoscillating instrument will cause more ultrasonic effectsin the irrigatingsolution than one that binds to canal walls (185).

US as an adjunctwith variousirrigating solutions contributes to theremoval of the smear layer (12, 145, 155, 176, 181, 186), however, itseems to be less effective in enhancing the activity of EDTA (154, 163,187189).

Thirty seconds to 1 minute of ultrasonic activation seems to besufficient to produce clean canals (157), whereas others recommend 2minutes (142). Shorter passive irrigation time makes it easier to main-tain the file in the center of the canal, thus preventing it from touchingthe canal walls (157). Syringe delivery of NaOCl every minute was aseffective as a continuous flow of NaOCl during 3 minutes of passiveultrasonic irrigation in the removal of dentin debris (135).

For ultrasonic irrigation, the use of medium power was suggested(171, 190 192). It is of interest to note that a combination of low-power US with NaOCl was not more effective than NaOCl alone (193,194).

Ultrasonic vibration can also be effective when touching the shankof a hand file inserted inside the canal. The hand file will transmit

vibrations to the irrigant inside the canal, but a greater risk for touchingdentinal walls exists.

To prevent a dampening effect, sonic or ultrasonic files should notcontact the canal walls; therefore, the use of smooth files is recom-mended (157). In contrast, ultrasonically activated stainless steel filestend to ledge and perforate canal walls because of their sharp cuttingsurfaces (195) (Fig. 6). The use of a smooth wire during ultrasonicirrigation in vitro was as effective as a K-file in debris removal (196).

Furthermore, US as an adjunct with EDTA enhanced the canal wallcleanliness after post space preparation in endodontically treated teeth,especially in the apical portion of the post space (197).

Ultrasonic Condensation of Gutta-Percha

Ultrasonically activated spreaders have been used to thermoplas-ticize gutta-percha in a warm lateral condensation technique. In somein vitro experiments, this was demonstrated to be superior to conven-tional lateral condensation with respect to sealing properties and den-sity of gutta-percha (198201). Ultrasonic spreaders that vibrate lin-early and produce heat, thus thermoplasticizing the gutta-percha,achieved a more homogeneous mass with a decrease in number andsize of voids and produced a more complete three-dimensional obtu-ration of the root canal system (201). This technique has also beenevaluated clinically with favorable results (202).

A number of obturation protocols have been described for ultra-sonic condensation of gutta-percha: (a) ultrasonic softening of the mas-ter cone followed by cold lateral condensation (198); (b) one or twotimes of ultrasonic activation after completion of cold lateral conden-

sation (203); (c) ultrasonic activation after placement of each secondaccessory cone (201); or (d) ultrasonic activation after placement of

each accessory cone (200, 204, 205).Warm lateral condensation combines the advantage of having con-

trol over the length of the root fill, similar to cold lateral condensation,with the superior ability of a thermoplasticized material to replicate thethree-dimensional shape of the root canal (201).Fromapracticalpointof view, ultrasonic condensation of gutta-percha is quickly masteredand has several advantages over other warm lateral condensation tech-niques. It was observed that heat was generated only during ultrasonicactivation, and the plugger appeared to cool rapidly once activationceased (204). The size of the heat carrier (ultrasonic spreader) can bechosen to match the diameter of the root canal, and the ultrasonicspreader can be curved to match the curvature of the root canal. Fur-thermore, gutta-percha does not stick to the ultrasonic file when the

ultrasonic unit is activated (198). Also, the low temperature producedby the unit at its lowest power setting may result in less volumetricchanges of gutta-percha upon cooling (206).

The obturation technique recommended when using the ultra-sonic techniques (204, 205) consists of initial placement of a gutta-perchaconetotheworkinglengthfollowedbycoldlateralcondensationof two or three accessory cones using a finger spreader. The ultrasonicspreader is then placed into the center of the gutta-percha mass 1 mmshort of the working length and activated at intermediate power toprevent charring of root surfaces and fracture of the ultrasonicspreader. After activation, the ultrasonic spreader is removed, and anadditional accessory cone is placed, followed by energizing with theactivated ultrasonic spreader. This process is repeated until the canal is

filled. During each subsequent step, the ultrasonic spreader should beplaced slightly more coronally.The ultrasonic spreader must be in the mass of gutta-percha for

about 10 secondsto achieve thermoplasticization. Leaving it in the canalfor more than 10 seconds can produce a rise in temperature that isdamaging to the root surface (204, 205).

In addition, it has been demonstrated that placement of sealerswith an ultrasonically energized file promoted a better covering of canalwalls with better filled accessory canals (evaluatedbyradiography) thanplacement of sealers with hand instruments (207, 208).

Placement of Mineral Trioxide Aggregate (MTA)

Witherspoon and Ham (209) described the use of US to aid in theplacement of MTA. The inherent irregularities and divergent nature of

Figure 6. SEM image of the instrumentation grooves on the root canal wallscreated by an ultrasonic file (1,150).

Review Article



8/15

some open apices may predispose the material to marginal gaps at thedentin interface. It was demonstrated that, with the adjunct of US, asignificantly better seal with MTA was achieved (210). Placement ofMTA with ultrasonic vibration and an endodontic condenser improvedthe flow, settling, and compaction of MTA. Furthermore, the ultrasoni-cally condensed MTA appeared denser radiographically, with fewervoids (210). These results contradicted those of Aminoshariae et al.(211), who concluded from an in vitro study that hand condensationwas superior.

The recommended placement method consists of selecting a con-denser tip, then picking up and placing the MTA with the ultrasonic tip,followed by activating the tip and slowly moving the MTA material downusing a 1- to 2-mm vertical packing motion. Direct ultrasonic energywill vibrate and generate a wavelike motion, which facilitates movingand adapting the cement to the canal walls (Fig. 5il). In a case ofrepairing a defect apical to the canal curvature, Ruddle (41) recom-mends incrementally placing MTA deep into a canal, then shepherdingit around the curvature with a flexible trimmed gutta-percha cone uti-lized as a plugger. A precurved 15 or 20 stainless steel file is theninserted into the material and placed to within 1 or 2 mmof the workinglength. This is followed by indirect ultrasound, which involves placingtheworkingend of an ultrasonic instrument on theshaft of the file. This

vibratory energy encourages MTA to move and conform to the configu-rations of the canal laterally as well as controlling its movement.

ThistechniquewasrecommendedinitiallyforplacingMTAinopenand diverging apices, but it can also be used to put the material inroot-end cavities, in perforations, and especially in perforations of thefloor of the pulp chamber (Fig. 5in).

Surgical Endodontics: Root-End Cavity Preparation and

Refinement and Placement of Root-End Obturation Material

Recent developments of new instruments and techniques have sig-nificantly enhanced the treatment outcome in apicoectomy with retro-filling (212). As the prognosis of endodontic surgery is highly depen-dent on good obturation and sealing of the root canal, an optimal cavity

preparation is an essential prerequisite for an adequate root-end fillingafter apicoectomy (20, 213, 214).

Root-end cavities have traditionally been prepared by means ofsmall round or inverted cone burs in a microhandpiece. In the mid-1980s, standardized instruments and aluminum oxide ceramic pins

were introduced for retrograde filling (215), but that system could notbe used in cases with limited working space or in teeth with large ovalcanals. Since sonically or ultrasonically driven microsurgical retrotipsbecamecommercially available in the early 1990s (216219),thisnewtechnique of retrograde root canal instrumentation has been estab-lished as an essential adjunct in periradicular surgery (217, 220, 221).However, the cutting properties of the retrotips at that time were limitedand seemed to be dependent on loading, power setting, and orientationofthetiptothelongaxisofthehandpiece( 222,223). In some retrotips,coolingof theworkingtip was insufficient, and dentin and bone were atrisk of being overheated (20).

The first root-end preparation using modified ultrasonic insertsfollowing an apicoectomy is attributed to Bertrand et al. (224). Others

followed, but it was not until 1987 that Flath and Hicks (225) furtherreported on the use of ultrasonics and sonics for root-end cavity prep-aration.

Conventional root-end cavity preparation using rotary burs in amicrohandpiece is faced with several problems (21, 226, 227),suchasa cavity preparation not being parallel to the canal, difficult accessto theroot end, and risk of lingual perforation of the root. Furthermore, theinability to prepare to a sufficientdepth,thus compromisingretention ofthe root-end filling material, means that the root-end resection proce-dure requires a longer cutting bevel, thus exposing more dentinal tu-bules and isthmus tissue, of which the latter is difficult to remove. Thedevelopment of ultrasonic and sonic retrotips has revolutionized root-end therapy, improving the surgical procedure with better access to the

root end, resulting in better canal preparation (226229). Ultrasonicretrotips come in a variety of shapes and angles, thus improving somesteps during the surgical procedures (213, 230, 231) (Figs. 7 and 8).

At first glance, the most relevant clinical advantages are the en-hanced access to root ends in a limited working space. This leads to asmaller osteotomy for surgical access because of the advantage of usingvarious angulations and the small size of the retrotips (232). However,a number of studies compared root-end preparations made with mi-crosurgical tips to those made with burs. They demonstrated additionaladvantages of this technique, such as deeper and more conservativecavities that follow the original path of the root canal more closely(221, 233237). A better-centered root-end preparation also lessensthe risk of lateral perforation (236238). Furthermore, the geometryof the retrotip design does not require a beveled root-end resection forFigure 7. Diamond-coated stainless steel ultrasonic surgical retrotips.

Figure 8. Smooth stainless steel ultrasonic surgical retrotips.

Review Article



9/15

surgical access (232), thus decreasing the number of exposed dentinaltubules (20, 239241) and minimizing apical leakage (242245).They also enable the removal of isthmus tissue present between twocanals within the same root (234, 236, 246248). It is considered atimesaving technique (234) thatseemstohavealowerfailurerate(20).

The cleaning effect and the cutting ability of ultrasonic retrotipshave been described as satisfactory by many authors (222, 223, 233, 237,249,250). Furthermore, USproduced less smearlayer in a retro-end cavitycompared to a slow-speed handpiece (214, 221, 233235, 251).

The refinement of cavity margins that were obtained with the ul-trasonic tips may positively affect the delivery of materials into the cav-ities and enhance their seal (214, 249, 252254), even if cavities pre-pared with erbium:YAGlasershave been shown to produce significantlylower microleakage than ultrasonic preparations (255).

In a study by Walmsley et al. (256) the breakage of ultrasonicroot-end preparation tips was investigated and attributed to the designof the tip. Increased angulation of retrotips increases the transverseoscillation and decreases the longitudinal oscillation, putting the great-est strain at the bend of the instrument. The authors suggested reducingthe angulation and increasing the dimensions of the tip to resist break-age. This may be true, but a straighter design will restrict access and athicker instrument prevents instrumentation of isthmuses. A controver-

sial issue with sonic or ultrasonic root-end preparation is the formationof cracks or microfractures and its implications for healing success(257, 258). Some studies indicated that this was a possible drawback(23, 238, 253, 259263). Other studies, however, disputed these find-ings and didnot report a higher prevalence of microfractures (19,237,264272). Khabbaz et al. (237) found that cracks did not correlatedirectly with thesurface area of the root-end surfaces but ratherwith thetype of retrotip used. Preparation with smooth stainless steel ultrasonictips produced fewer intradentin cracks than diamond-coated stainlesssteel ultrasonic tips and sonic diamond-coated tips.

The influence of root-end microfractures on the periradicularhealing process and apical leakage should be clarified (226). Apicalresorption after healing (273) may eliminate the surface defects and

contribute to the overall success of treatment. Also, such defects can beremoved by finishing resected and retrofilled root-end surfaces (274).Several in vivo studies reported excellent success rates when the root-end preparation was performed using ultrasonic retrotips (21, 212,275-283), thus demonstrating that modern surgical endodontic treat-ment using an operating microscope and ultrasonic tips significantlyimproves the outcome compared to the traditional techniques (284).

It is recommended that the ultrasonicunitbe set at medium power(267) and the cavities be prepared to a depth of 2.5-3 mm (285). Thisdepth allows for a minimum thickness of material that can still providean effective apical seal (286). The cavity walls should be parallel andfollow the anatomic outline of the pulpal space (230, 287). It has alsobeen suggested that root-end cavities should be initiated with a dia-

mond-coated retrotip, using its better cutting ability to provide the maincavity. This aids in the removal of root canal obturation materials andshouldbefollowedbyasmoothretrotiptosmoothandcleancavitywalls(248).

A condenser tip ultrasonically activated can be utilized for place-ment of retrograde filling materials, as the ultrasonic vibration is meantto improve the flow, settling and compaction of these materials to root-enddentinalwalls.Thisshouldimprovethedeliveryofmaterialsintothecavity thus enhancing their seal (210).

Ultrasonic tips can also be used to polish root end material andapical surfaces. Utilizing specific ultrasonic tips for refinement of theexternal radicular surface may be beneficial in the elimination of ex-traradicular bacteria, which may be responsible for infection (288,289).

Root Canal Preparation

Ultrasonic devices were introduced for use in root canal prepara-tion in 1957 by Richman (9). In 1980, Martin et al. (11, 12) demon-strated the ability of ultrasonically activated K-type files to cut dentin. Acommercial ultrasonic unit, designed by Cunningham and Martin(147), was introduced in 1982. Barnett et al. (290, 291) and Tronstadet al. (292) were the first to report on its use in endodontics.

Several studies have shown that ultrasonically or sonically pre-

pared teeth have significantly cleaner canals than teeth prepared byhand instruments (14, 147149, 293296). Numerous studies haveanalyzed the different characteristics of ultrasonically activated files,such as cutting efficiency (11, 12, 297302), effect on bacteria (168,303, 304), characteristics of root canal preparation (153, 305313),mechanical and technical features offiles and handpieces (314318),and clinical implications (319323).

The results of the above studies can be summarized as being con-tradictory. They failed to demonstrate the superiority of US or sonics asa primary instrumentation technique, as no improved debridement wasaccomplished compared with hand instrumentation (22, 140, 152,160, 176, 194, 291, 324342). The relative inefficiency of ultrasonicdebridement has been attributed to file constraint within the unflaredroot canal space (343). A modification of the technique in which ultra-sound is activated for a few minutes after hand preparation has insteadresulted in greater canal and isthmus cleanliness compared with handpreparation alone (151, 177, 344346).

Despite the multitude of studies conducted on ultrasonic root ca-nal preparation with ultrasonically activated files, the current consensusis that this is not a viable clinical technique.

ConclusionsIt can be concluded from this review of the literature that US offers

many applications and advantages in clinical endodontics. Improvedvisualization combined with a more conservative approach when selec-tively removing tooth structure, particularly in difficult situations in

which a specific angulation or tip design permits access to restrictedwork areas, offers opportunities that are not possible with conventionaltreatment. As a result, access refinement, location of calcified canals,and removal of separated instruments or posts have generated morepredictable results. In addition, better action of irrigation solutions andcondensation of gutta-percha have benefited from the use of US. Root-end cavity preparation followed by placement of materials in an areathat is more often than not constrained has especially improved thequality of treatment and long-term success. Finally, integration of newtechnologies such as US, leading to improved techniques and use ofmaterials, has changed the way endodontics is being practiced today.

References1. Catuna MC. Ultrasonic energy: a possible dental application. Preliminary report of

an ultrasonic cutting method. Ann Dent 1953;12:256 60.2. Postle HH. Ultrasonic cavity preparation. J Prosthet Dent 1958;8:153 60.3. Balamuth L. The application of ultrasonic energy in the dental field. In: Brown B,

Gordon D, eds. Ultrasonic techniques in biology and medicine. London: Ilife;1967:194205.

4. Oman CR, Applebaum E. Ultrasonic cavity preparation II. Progress report. J AmDent Assoc 1954;50:4147.

5. Nielsen AG, Richards JR, Wolcott RB. Ultrasonic dental cutting instrument: I. J AmDent Assoc 1955;50:3929.

6. Street EV. Critical evaluation of ultrasonics in dentistry. J Prosthet Dent1959;9:3241.

7. Zinner DD. Recent ultrasonic dental studies including periodontia, without the useof an abrasive. J Dent Res 1955;34:7489.

8. Johnson WN, Wilson JR. Application of the ultrasonic dental unit to scaling proce-dures. J Periodontol 1957;28:26471.

Review Article



10/15

9. Richman RJ. The use of ultrasonics in root canal therapy and root resection. MedDent J 1957;12:128.

10. Martin H. Ultrasonic disinfection of the root canal. Oral Surg Oral Med Oral Pathol1976;42:929.

11. Martin H, Cunningham WT, Norris JP, Cotton WR. Ultrasonic versus hand filing ofdentin: a quantitative study. Oral Surg Oral Med Oral Pathol 1980;49:7981.

12. Martin H, Cunningham WT, Norris JP. A quantitative comparison of the ability ofdiamond and K-type files to remove dentin. Oral Surg Oral Med Oral Pathol1980;50:5668.

13. Martin H, Cunningham W. Endosonic endodontics: the ultrasonic synergistic sys-

tem. Int Dent J 1984;34:198203.14. Martin H, Cunningham W. Endosonics: the ultrasonic synergistic system of end-odontics. Endod Dent Traumatol 1985;1:2016.

15. Stock CJR. Current status of the use of ultrasound in endodontics. Int Dent J1991;41:175 82.

16. Laurichesse JM. La technique de lappui parietal (T.A.P.) Rev Franc Endod1985;4:1938.

17. Ahmad M, Roy RA, Kamarudin AG, Safar M. The vibratory pattern of ultrasonic filesdriven piezoelectrically. Int Endod J 1993;26:1204.

18. Lumley PJ, Walmsley AD, Marquis PM. Effect of air inlet ring opening on sonichandpiece performance. J Dent 1994;22:3769.

19. Lloyd A, Jatmberzins A, Dummer PM, Bryant S. Root-end cavity preparation usingthe Micro Mega Sonic Retro-prep tip: SEM analysis. Int Endod J 1996;29:295301.

20. von ArxT, KurtB, Ilgenstein B, HardtN. Preliminaryresultsand analysisof a newsetof sonic instruments for root-end cavity preparation. Int Endod J 1998;31:32 8.

21. von Arx T, Kurt B. Root-end cavity preparation after apicoectomy using a new type

of sonic and diamond-surfaced retrotip: a 1-year follow-up study. J Oral MaxillofacSurg 1999;57:65661.

22. Ahmad M, Pitt Ford TR, Crum LA. Ultrasonic debridement of root canals: an insightinto the mechanisms involved. J Endod 1987;13:93101.

23. Layton CA, Marshall JG, Morgan LA, Baumgartner JC. Evaluation of cracks associ-ated with ultrasonic root-end preparation. J Endod 1996;22:15760.

24. Walmsley AD. Ultrasound and root canal treatment: the need for scientific evalua-tion. Int Endod J 1987;20:10511.

25. Lumley PJ, Walmsley AD, Laird WRE. An investigation into the occurrence of cavi-tational activity during endosonic instrumentation. J Dent 1988;16:120 2.

26. Laird WRE, Walmsley AD. Ultrasound in dentistry: Part 1. Biophysical interactions.J Dent 1991;19:147.

27. Lea SC, Walmsley AD, Lumley PJ, Landini G. A new insight into the oscillationcharacteristics of endosonic files used in dentistry. Phys Med Biol 2004;49:2095102.

28. Walmsley AD. Applications of ultrasound in dentistry. Ultrasound Med Biol

1988;14:714.29. Walmsley AD,Laird WRE,Lumley PJ. Ultrasound in dentistry: Part2. Periodontology

and endodontics. J Dent 1992;20:117.30. Peters MC, McLean ME. Minimally invasive operative care. I. Minimal intervention

andconceptsfor minimallyinvasive cavity preparations.J Adhes Dent2001;3:716.31. Peters MC, McLean ME. Minimally invasive operative care. II. Contemporary tech-

niques and materials: an overview. J Adhes Dent 2001;3:1731.32. Sheets CG, Paquette JM. Ultrasonic tips for conservative restorative dentistry. Dent

Today 2002;21:102 4.33. Clark D. The operatingmicroscope andultrasonics:a perfect marriage.Dent Today

2004;23:7481.34. Buchanan LS. Innovations in endodontics instruments and techniques: how they

simplify treatment. Dent Today 2002;21:5261.35. Sempira HN, Hartwell GR. Frequency of second mesiobuccal canals in maxillary

molars as determined by use of an operating microscope: a clinical study. J Endod2000;26:673 4.

36. Gorduysus MO, Gorduysus M, Friedman S. Operating microscope improves nego-tiation of second mesiobuccal canals in maxillarymolars.J Endod 2001;27:6836.

37. Rampado ME, Tjaderhane L, Friedman S, Hamstra SJ. The benefit of the operatingmicroscope for access cavity preparation by undergraduate students. J Endod2004;30:8637.

38. Lin YH, Mickel AK, Jones JJ, Montagnese TA, Gonzalez AF. Evaluation of cuttingefficiency of ultrasonic tips used in orthograde endodontic treatment. J Endod2006;32:35961.

39. PazE, SatovskyJ, Moldauer I. Comparisonof thecuttingefficiency oftwo ultrasonicunits utilizing two different tips at two different power settings. J Endod 2005;31:8246.

40. Waplington M, Lumley PJ, Bunt L. An in vitro investigation into the cutting action ofultrasonic radicular access preparation instruments. Endod Dent Traumatol2000;16:15861.

41. Ruddle CJ. Nonsurgical endodontic retreatment. J Calif Dent Assoc 2004;32:47484.

42. Johnson WB, Beatty RG. Clinical technique for the removal of the root canal ob-structions. J Am Dent Assoc 1988;117:4736.

43. HulsmannM. Methods for removing metalobstructionsfrom the rootcanal. EndodDent Traumatol 1993;9:22337.

44. Fors UGH, Berg JO. Endodontic treatment of root canals obstructed by foreignobjects. Int Endod J 1986;19:210.

45. Weisman MI. The removal of difficult silver cones. J Endod 1983;9:2101.46. Meidinger DL, Kabes BJ. Foreign object removal utilizing the Cavi-Endo ultrasonic

instrument. J Endod 1985;11:3014.47. Glick DH, Frank AL. Removal of silver points and fractured posts by ultrasonics.

J Prosthet Dent 1986;55:2125.48. Chenail BL, TeplitskyPE. Orthograde ultrasonic retrivialof rootcanal obstructions.J Endod 1987;13:18690.

49. Stamos DE, Stamos DG, Perkins SK. Retreatodontics and ultrasonics. J Endod1988;14:3942.

50. Hulsmann M. The removal of silver cones using different techniques. Int Endod J1990;23:298303.

51. Sprigs K, Gettleman B, Messer H. Evaluation of a new method for silver pointsremoval. J Endod 1990;16:3358.

52. Masserann J. The extraction of posts broken deeply in the roots. Actual Odontos-tomatol 1986;75:392 402.

53. Gettleman BH, Spriggs KA, Messer HH, El Deeb ME. Removal of canal obstructionswith the Endo Extractor. J Endod 1991;17:608 11.

54. Roig-Greene JL. The retrieval of foreign objects from root canals: a simple aid.J Endod 1983;9:3947.

55. Gaffney JL, Lehman JW, Miles MJ. Expanded use of the ultrasonic scaler. J Endod

1981;5:2289.56. Souyave LC, Inglis AT, Alcalay M. Removal of fractured instruments using ultrason-ics. Br Dent J 1985;159:2513.

57. Nagai O, Tani N, Kayaba Y, Kodama S, Osada T. Ultrasonic removal of brokeninstruments in root canals. Int Endod J 1986;19:298304.

58. Grossman LI. Fate of endodontically treated teeth with fractured root canal instru-ments. J Br Endod Soc 1968;2:357.

59. Crump MC, Natkin E. Relationship of broken root canal instruments to endodonticcase prognosis: a clinical investigation. J Am Dent Assoc 1970;80:13417.

60. Hulsmann M. Removal of fractured instruments using a combined automated/ultrasonic technique. J Endod 1994;20:1447.

61. Hulsmann M, Schinkel I. Influence of several factors on the success or failure ofremoval of fractured instruments from the root canal. Endod Dent Traumatol1999;15:2528.

62. Nehme WB. Elimination of intracanal metallic obstructions by abrasion using anoperational microscope and ultrasonics. J Endod 2001;27:3657.

63. Ward JR, Parashos P, Messer HH. Evaluation of an ultrasonic technique to removefractured rotary nickel-titanium endodontic instruments from root canals: clinicalcases. J Endod 2003;29:7647.

64. Ruddle CJ. Nonsurgical retreatment. In: Cohen S, Burns RC, eds. Pathways of thepulp, 8th ed. St Louis: Mosby; 2002:875930.

65. Ward JR, Parashos P, Messer HH. Evaluation of an ultrasonic technique to removefractured rotary nickel-titanium endodontic instruments from root canals: an ex-perimental study. J Endod 2003;29:75663.

66. Hulsmann M. Removal of silver cones and fractured instruments using the canalfinder system. J Endod 1990;16:596600.

67. Feldman G, Solomon C, Notaro P, Moskovitz E. Retrieving broken endodontic in-struments. J Am Dent Assoc 1974;88:58891.

68. Shen Y, Peng B, Cheung GS. Factors associated with the removal of fractured NiTiinstruments from root canal systems. Oral Surg Oral Med Oral Pathol Oral RadiolEndod 2004;98:60510.

69. Souter NJ, Messer HH. Complications associated with fractured file removal usingan ultrasonic technique. J Endod 2005;31:4502.

70. Gilbert BOI, Rice T. Re-treatment in endodontics. Oral Surg Oral Med Oral Pathol1987;64:3338.

71. Ruddle CJ. Micro-endodontic non-surgical retreatment. Dent Clin North Am1997;41:42954.

72. DArcangelo C, Varvara G, De Fazio P. Broken instrument removal-two cases.J Endod 2000;26:36870.

73. Ward JR. The use of an ultrasonic technique to remove a fractured rotary nickel-titanium instrument from the apical third of a curved root canal. Aust Dent J2003;29:2530.

74. Wu MK, van der Sluis LW, Wesselink PR. The risk of furcal perforation in mandib-ular molars using Gates-Glidden drills with anticurvature pressure. Oral Surg OralMed Oral Pathol Oral Radiol Endod 2005;99:37882.

75. Zuckerman O, Katz A, Pilo R, Tamse A, Fuss Z. Residual dentin thickness in mesialroots of mandibular molars preparedwith Lightspeedrotaryinstrumentsand Gates-Glidden reamers. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;96:3515.

Review Article



11/15

76. Kuttler S, McLeanA, Dorn S,Fischzang A.The impactof post space preparationwithGates-Glidden drills on residual dentin thickness in distal roots of mandibularmolars. J Am Dent Assoc 2004;135:9039.

77. Tilk MA,Lommel TJ,Gerstein H. A study ofmandibular andmaxillary root widthstodetermine dowel size. J Endod 1979;5:79 82.

78. PiloR, TamseA. Residual dentin thickness in mandibular premolars prepared withGates Glidden and ParaPost drills. J Prosthet Dent 2000;83:61723.

79. Pilo R, Corcino G, Tamse A. Residual dentin thickness in mandibular premolarsprepared with hand and rotatory instruments. J Endod 1998;24:4014.

80. TamseA, Katz A,PiloR. Furcationgrooveof buccalrootof maxillaryfirst premolars:

a morphometric study. J Endod 2000;26:35963.81. Raiden G, Costa L, Koss S, Hernandez JL, Acenolaza V. Residual thickness of root infirst maxillary premolars with post space preparation. J Endod 1999;25:5025.

82. Katz A, Wasenstein-Kohn S, Tamse A, Zuckerman O. Residual dentin thickness inbifurcated maxillary premolars after root canal and dowel space preparation.J Endod 2006;32:2025.

83. Raiden G, Koss S, Costa L, Hernandez JL. Radiographic measurement of residualroot thickness in premolars with post preparation. J Endod 2001;27:296 8.

84. Iqbal MK, Rafailov H, Kratchman SI, Karabucak B. A comparison of three methodsfor preparing centered platforms around separated instruments in curved canals.J Endod 2006;32:4851.

85. Stamos DE, Gutmann JL. Survey of endodontic retreatment methods usedto removeintraradicular posts. J Endod 1993;19:366 9.

86. Berbert A, Filho MT, Ueno AH, Bramante CM, Ishikiriama A. The influence ofultrasound in removing intraradicular posts. Int Endod J 1995;28:546.

87. Berbert A, Filho MT, Ueno AH, Bramante CM, Ishikiriama A. The influence of

ultrasound in removing intraradicular posts. Int Endod J 1995;28:1002.88. Altshul JH, Marshall G, Morgan LA, Baumgartner JC. Comparison of dentinal crackincidence and of post removal time resulting from post removal by ultrasonic ormechanical force. J Endod 1997;23:6836.

89. Williams VD, Bjorndal AM. The Masserann technique for the removal of fracturedposts in endodontically treated teeth. J Prosthet Dent 1983;49:468.

90. Bando E, Kawashima T, Tiu IT, Kubo Y, Nakano M. Removing dowels in difficultteeth. J Prosthet Dent 1985;54:346.

91. Shemen BB, Cardash HS. A technique for removing posts. J Prosthet Dent1985;54:2001.

92. Cheuk SL, Karam PE. Removal of parallel prefabricated posts: a clinical report.J Prosthet Dent 1988;59:5313.

93. Machtou P, Sarfati P, Cohen AG. Post removal prior to retreatment. J Endod1989;15:552 4.

94. Parreira FR, OConnor RP, Hutter JW. Cast prosthesis removal using ultrasonicsand a thermoplastic resin adhesive. J Endod 1994;20:1413.

95. Krell KV, Jordan RD, Madison S, Aquilino S. Using ultrasonic scalers to removefractured posts. J Prosthet Dent 1986;55:469.

96. Castrisos T, Abbott PV. A survey of methods used for post removal in specialistendodontic practice. Int Endod J 2002;35:17280.

97. Hauman CHJ,ChandlerNP, Purton DG. Factors influencing the removal of posts. IntEndod J 2003;36:68790.

98. Ruddle CJ. Nonsurgical retreatment. J Endod 2004;30:82745.99. De Rijk WG Removal of fiber posts from endodontically treated teeth. Am J Dent

2000;13:19B21B.100. Gesi A, Magnolfi S, Goracci C, Ferrari M. Comparison of two techniques for remov-

ing fiber posts. J Endod 2003;29:5802.101. LindemannM, YamanP, DennisonJB, Herrero AA.Comparison of theefficiency and

effectiveness of various techniques for removal of fiber posts. J Endod 2005;31:5202.

102. Buoncristiani J, Seto BG, Caputo AA. Evaluation of ultrasonic and sonic instrumentsfor intraradicular post removal. J Endod 1994;20:4869.

103. Jaeger JC. Elasticity, fracture and flow, 1st ed. London: Methuen; 1962: 133.104. OBrien J. Dental Materials, properties and selections, 1st ed. Chicago: Quintes-

sence; 1989: 54951.105. Lassila LVJ, Tanner J, Le Bell A-M, Narva K, Vallittu P. Flexural properties of fiber

reinforced root canal posts. Dent Mater 2004;20:29 36.106. Phillips RW. Skinners science of dental materials.Philadephia: Saunders; 1996.107. Garrido AD, Fonseca TS, Alfredo E, Silva-Sousa YT, Sousa-Neto MD. Influence of

ultrasound, with and without water spray cooling, on removal of posts cementedwith resin or zinc phosphate cements. J Endod 2004;30:1736.

108. Watanabe EK, Yatani H, Yamashita A, Ishikawa K, Suzuki K. Effects of thermocyclingon the tensile bond strength between resin cement and dentin surfaces after tem-porary cement application. Int J Prosthodont 1999;12:2305.

109. Johnson WT, Leary JM, Boyer DB. Effect of ultrasonic vibration on post removal inextracted human premolar teeth. J Endod 1996;22:4878.

110. Yoshida T, Shunji G, Tomomi I, Shibata T, Sekine I. An experimental study of theremoval of cemented dowel-retained cast cores by ultrasonic vibration. J Endod1997;23:23941.

111. Gomes APM, Kubo CH, Santos DR, Padilha RQ. The influence of ultrasound on theretention of cast posts cemented with different agents. Int Endod J 2001;34:939.

112. Smith BJ. Removal of fractured posts using ultrasonic vibration: an in vivo study.J Endod 2001;27:632 4.

113. Dixon EB,Kaczkowski PJ, NichollsJI, Harrington GW. Comparison of twoultrasonicinstruments for post removal. J Endod 2002;28:1115.

114. Alfredo E, Garrido AD, Souza-Filho CB, Correr-Sobrinho L, Sousa-Neto MD. In vitroevaluation of the effect of core diameter for removing radicular post with ultra-sound. J Oral Rehabil 2004;31:5904.

115. Silva MR, Biffi JC, Mota AS, Fernandes Neto AJ, Neves FD. Evaluation of intracanal

post removal using ultrasound. Braz Dent J 2004;15:119 26.116. Braga NM, Alfredo E, Vansan LP, Fonseca TS, Ferraz JA, Sousa-Neto MD. Efficacy ofultrasound in removal of intraradicular posts using different techniques. J Oral Sci2005;47:11721.

117. Chandler NP, Qualtrough AJE, Purton DG. Comparison of two methods for removalof root canal posts. Quintessence Int 2003;34:5346.

118. Ruddle CJ. Nonsurgical endodontic retreatment. J Calif Dent Assoc 1997;25:76986.

119. Bergeron BE, Murchison DF, Schindler DF, Walker WA III. Effect of ultrasonicvibration and various sealer and cement combinations on titanium post removal.J Endod 2001;27:137.

120. Budd JC, Gekelman D, White JM. Temperature rise of the post and on the rootsurface during ultrasonic post removal. Int Endod J 2005;38:70511.

121. Gluskin AH, Ruddle CJ, Zinman EJ. Thermal injury through intraradicular heattransfer using ultrasonic devices: precautions and practical preventive strategies.J Am Dent Assoc 2005;136:128693.

122. Dominici JT, Clark S, Scheetz J, Eleazer PD. Analysis of heat generation using ultra-sonic vibration for post removal. J Endod 2005;31:3013.123. Satterthwaite JD, Stokes AN, Frankel NT. Potential for temperature change during

application of ultrasonic vibrationto intra-radicular posts. EurJ ProsthodontRestorDent 2003;11:516.

124. Sieraski SM, Zillich RM. Silver point retreatment: review and case report. J Endod1983;9:359.

125. Suter B. A new method for retrieving silver points and separated instruments fromroot canals. J Endod 1998;24:4468.

126. Nehme W. A new approach for the retrieval of broken instruments. J Endod1999;25:6335.

127. Cherukara GP,PollockGR, Wright PS.Case report: removal of fracturedendodonticposts with a sonic instrument. Eur J Prosthodont Restor Dent 2002;10:236.

128. Abou-RassM, PiccininoMV. The effectiveness of fourclinicalirrigation methods onthe removal of root canal debris. Oral Surg Oral Med Oral Pathol 1982;54:3238.

129. Lee SJ, Wu MK, WesselinkPR. The effectiveness of syringe irrigationand ultrasonicsto remove debris fromsimulatedirregularities within prepared rootcanal walls. IntEndod J 2004;37:6728.

130. Baker NA, Eleazer PD, Averbach RE. Scanning electron microscopic study of theefficacy of various irrigation solutions. J Endod 1975;1:12735.

131. Chow TW. Mechanicaleffectivenessof rootcanal irrigation. J Endod 1983;9:4759.132. Teplitsky PE, Chenail BL, Mack B, Machnee CH. Endodontic irrigation: a compari-

son of endosonic and syringe delivery systems. Int Endod J 1987;20:233 41.133. Ram Z. Effectiveness of root canal irrigation. Oral Surg Oral Med Oral Pathol

1977;44:30612.134. Walters MJ, Baumgartner JC, Marshall JG. Efficacy of irrigation with rotary instru-

mentation. J Endod 2002;28:8379.135. vanderSluisLW, GambariniG, Wu MK,WesselinkPR. Theinfluence ofvolume, type

of irrigant and flushing method on removing artificially placed dentine debris fromthe apical root canal during passive ultrasonic irrigation. Int Endod J 2006;39:4726.

136. Wu MK, Wesselink PR. Efficacy of three techniques cleaning the apical portion ofcurved root canals. Oral Surg Oral Med Oral Pathol 1995;79:4926.

137. Baumgartner JC, Cuenin PR. Efficacy of several concentrationsof sodium hypochlo-rite for root canal irrigation. J Endod 1992;18:60512.

138. Gutarts R, Nusstein J, Reader A, Beck M. In vivo debridement efficacy of ultrasonicirrigation following hand-rotary instrumentation in human mandibular molars.J Endod 2005;31:166 70.

139. Griffiths BM, Stock CJR. The efficiency of irrigants in removing root canal debriswhen used with an ultrasonicpreparation technique. Int Endod J 1986;19:277 84.

140. Ahmad M, Pitt Ford TR, Crum LA. Ultrasonic debridement of root canals: acousticstreaming and its possible role. J Endod 1987;13:490 9.

141. Krell KV, Johnson RJ. Irrigation patterns during ultrasonic canal instrumentation.Part II. Diamond-coated files. J Endod 1988;14:5357.

142. Krell KV, Johnson RJ, Madison S. Irrigation pattern during ultrasonic canal instru-mentation. Part I. K-type files. J Endod 1988;14:658.

143. Jensen SA, Walker TL, Hutter JW, Nicoll BK. Comparison of cleaning efficacy ofpassive sonic activationand passive ultrasonic activation afterhand instrumentationin molar root canals. J Endod 1999;25:7358.

Review Article



12/15

144. Druttman ACS, Stock CJR. An in vitro comparison of ultrasonic and conventionalmethods of irrigant replacement. Int Endod J 1989;22:1748.

145. CheungGS, Stock CJ.In vitrocleaningabilityof root canal irrigantswithand withoutendosonics. Int Endod J 1993;26:33443.

146. Weller RN, Brady JM, Bernier WE. Efficacy of ultrasonic cleaning. J Endod1980;6:7403.

147. CunninghamWT, Martin H.A scanningelectronmicroscopeevaluation ofroot canaldebridement with the endosonic ultrasonic synergistic system. Oral Surg Oral MedOral Pathol 1982;53:52731.

148. Cunningham WT,Martin H, Forrest WR. Evaluationof rootcanal debridement by the

endosonic ultrasonic synergistic system. Oral Surg Oral Med Oral Pathol 1982;53:4014.149. Cunningham WT, Martin H, Pelleu GB, Stoops DE. A comparison of antimicrobial

effectiveness of endosonic and hand root canal therapy. Oral Surg Oral Med OralPathol 1982;54:23841.

150. Giangrego E. Changing concepts in endodontic therapy. J Am Dent Assoc1985;110:4708.

151. Goodman A,Beck M,MelfiR, MeyersW. Anin vitrocomparisonof theefficacy ofthestep-backtechnique versus a step-back/ultrasonic techniquein humanmandibularmolars. J Endod 1985;11:24956.

152. Stamos DE, Sadeghi EM, Haasch GC, Gerstein H. An in vitro comparison study toquantitate the debridement ability of hand, sonic, and ultrasonic instrumentation.J Endod 1987;13:434 40.

153. Lumley PJ, Walmsley AD, Walton RE, Rippin JW. Cleaning of oval canals usingultrasonic or sonic instrumentation. J Endod 1993;19:4537.

154. Cameron JA. The choice of irrigant during hand instrumentation and ultrasonic

irrigation of the root canal: a scanning electron microscope study. Aust Dent J1995;40:8590.155. Cameron JA. Factors affecting the clinical efficiency of ultrasonic endodontics: a

scanning electron microscopy study. Int Endod J 1995;28:4753.156. Ardila CN, Wu M-K, Wesselink PR. Percentage of filled canal area in mandibular

molars after conventional root canal instrumentation and after a noninstrumenta-tion technique (NIT). Int Endod J 2003;36:5918.

157. Sabins RA, Johnson JD, Hellstein JW. A comparison of the cleaning efficacy ofshort-term sonic and ultrasonic passive irrigation after hand instrumentation inmolar root canals. J Endod 2003;29:6748.

158. Ferreira RB, Alfredo E, Porto de Arruda M, Silva Sousa YT, Sousa-Neto MD. Histo-logical analysis of the cleaning capacity of nickel-titanium rotary instrumentationwith ultrasonic irrigation in root canals. Aust Endod J 2004;30:56 8.

159. Moorer WR, Wesselink PR. Factors promoting the tissue dissolving capability ofsodium hypochlorite. Int Endod J 1982;15:18796.

160. Ahmad M, Pitt Ford TR,CrumLA, WaltonAJ. Ultrasonic debridement of root canals:acoustic cavitation and its relevance. J Endod 1988;14:486 93.

161. Lee SJ, Wu MK, Wesselink PR. The effectiveness of ultrasonic irrigation to removeartificially placed dentine debris from different-sized simulated plastic root canals.Int Endod J 2004;37:60712.

162. Sjogren U, Sunqvist G. Bacteriologic evaluation of ultrasonic root canal instrumen-tation. Oral Surg Oral Med Oral Pathol 1987;63:36670.

163. Abbot PV, Heijkoop PS, Cardaci SC, Hume WR, Heithersay GS. An SEM study of theeffects of different irrigation sequences and ultrasonics. Int Endod J 1991;24:30816.

164. Briseno BM, Wirth R, Hamm G, Standhartinger W. Efficacy of different irrigationmethods and concentrations of root canal irrigation solutions on bacteria in theroot canal. Endod Dent Traumatol 1992;8:6 11.

165. Huque J, Kota K, Yamaga M, Iwaku M, Hoshino E. Bacterial eradication from rootdentine by ultrasonic irrigation with sodium hypochlorite. Int Endod J 1998;31:24250.

166. Mayer BE, Peters OA, Barbakow F. Effects of rotary instruments and ultrasonicirrigation on debris andsmear layerscores:a scanningelectronmicroscopic study.Int Endod J 2002;35:5829.

167. Ahmad M. Effect of ultrasonic instrumentation on Bacteroides intermedium.Endod Dent Traumatol 1989;5:836.

168. Williams AR. Disorganization and disruption mammalian and ameboid cells byacoustic streaming. J Acoust Soc Am 1972;52:68893.

169. Spoleti P, Siragusa M, Spoleti MJ. Bacteriological evaluation of passive ultrasonicactivation. J Endod 2003;29:12 4.

170. Bystrom A, Sundqvist G. Bacteriologic evaluation of the efficacy of mechanical rootcanal instrumentation in endodontic therapy. Scand J Dent Res 1981,89:321 8.

171. Cameron JA. The synergistic relationship between ultrasound and sodium hypo-chlorite: a scanning electron microscope evaluation. J Endod 1987;13:5415.

172. Cunningham WT, BalekjianBA. The effect of temperatureon the collagen dissolvingability of sodium hypochlorite as an endodontic irrigant. Oral Surg Oral Med OralPathol 1980;49:1757.

173. AhmadM. Measurements of temperaturegenerated byultrasonic filein vitro. EndodDent Traumatol 1990;6:2301.

174. Senia ES, Marshall FJ, Rosen J. The solvent action of sodium hypochlorite on pulptissue of extracted teeth. Oral Surg Oral Med Oral Pathol 1971;31:96103.

175. McComb D, Smith DC, Beagrie GS. The results of in vivo endodontic chemome-chanical instrumentation: a scanning electron microscopic study. J Br Endod Soc1976;9:118.

176. Langeland K, Liao K, Pascon EA. Work-saving devices in endodontics: efficacy ofsonic and ultrasonic techniques. J Endod 1985;11:499510.

177. Lev R, Reader A, Beck M, Meyers W. An in vitro comparison of the step-backtechnique versus a step-back ultrasonic technique for 1 and 3 minutes. J Endod1987;13:5239.

178. Heard F, Walton RE.Scanningelectron microscopestudycomparing fourrootcanalpreparation techniques in small curved canals. Int Endod J 1997;30:32331.179. Usman N, Baumgartner JC, Marshall JG. Influence of instrument size on root canal

debridement. J Endod 2004;30:1102.180. Walmsley AD, Williams AR. Effects of constraint on the oscillatory pattern of end-

odontic files. J Endod 1989;15:18994.181. Guerisoli DMZ, Marchesan MA, Walmsley AD, Lumley PJ, Pecora JD. Evaluation of

smear layer removal by EDTAC and sodium hypochlorite with ultrasonic agitation.Int Endod J 2002;35:418421.

182. Karadag LS, Tinaz AC, Mihcioglu T. Influence of passive ultrasonic activation on thepenetration depth of different sealers. J Contemp Dent Pract 2004;517.

183. van der Sluis LW, Wu MK, Wesselink PR. The efficacy of ultrasonic irrigation toremove artificially placed dentine debris from human root canals prepared usinginstruments of varying taper. Int Endod J 2005;38:7648.

184. Zehnder M. Root canal irrigants. J Endod 2006;32:38998.185. Roy RA, Ahmad M, Crum LA. Physical mechanisms governing the hydrodynamic

response of an oscillating ultrasonic file. Int Endod J 1994;27:197207.186. Cymerman J, Jerome L, Moodnik R. A scanning electron microscope study

comparing the efficacy of handinstrumentation withultrasonic instrumentationof the root canal. J Endod 1983;9:32731.

187. Cameron JA. The use of ultrasonics in the removal of the smear layer: a scanningelectron microscope study. J Endod 1983;9:28992.

188. Cameron JA. The use of ultrasound and an EDTAurea peroxide compound in thecleansing of root canals: an SEM study. Aust Dent J 1984;29:805.

189. Ciucchi B, Khettabi M, Holz J. The effectiveness of different endodontic irrigationprocedures on the removal of the smear layer: a scanning electron microscopicstudy. Int Endod J 1989;22:218.

190. Cameron JA. The use of ultrasound in the cleaning of root canals: a clinical report.J Endod 1982;8:4713.

191. Crabb HSM. The cleansing of root canals. Int Endod J 1982;15:626.192. Cameron JA. The use of ultrasound for the removal of the smear layer. The effect of

sodium hypochlorite concentrations: SEM study. Aust Dent J 1988;33:193200.

193. Tauber R, Morse DR, Sinai IA, Furst ML. A magnifying lens comparative evaluationof conventional and ultrasonically energized filing. J Endod 1983;9:26974.

194. Goldman M, White RR, Moser CR, Tenca JI. A comparison of three methods ofcleaning and shaping the root canal in vitro. J Endod 1988;14:712.

195. Sundqvist G, Figdor D. Endodontic treatment of apical periodontitis. In: rstavik D,Pitt Ford TR, eds. Essential endodontology, 2nd ed. Oxford, UK: Blackwell Science,1998:242270.

196. van der Sluis LW, Wu MK, Wesselink PR. A comparison between a smooth wire anda K-file in removing artificially placed dentine debris from root canals in resinblocks during ultrasonic irrigation. Int Endod J 2005;38:5936.

197. SerafinoC, Gallina G, Cumbo E, Ponticelli F, Goracci C, Ferrari M. Ultrasound effectsafter post space preparation: an SEM study. J Endod 2006;32:54952.

198. Moreno A. Thermomechanical softened gutta-percha root canal filling. J Endod1977;3:1868.

199. Joiner HL, Canales ML, Del Rio CE. Temperature changes in thermoplasticizedgutta-percha: a comparison of twoultrasonicunits. Oral Surg Oral MedOralPathol

1989;68:7649.200. Baumgardner KR, KrellKV. Ultrasonic condensation of gutta-percha: an in vitrodye

penetration and scanning electron microscope study. J Endod 1990;16:2539.201. Deitch AK, Liewehr FR, West LA, William R. Patton WR. A comparison of fill density

obtainedby supplementingcold lateral condensationwith ultrasonic condensation.J Endod 2002;28:6657.

202. Zmener O, Banegas G. Clinical experience of root canal filling by ultrasonic con-densation of gutta-percha. Endod Dent Traumatol 1999;15:579.

203. Amditis C,BlacklerSM, BryantRW, HewittGH. Theadaptationachieved byfourrootcanalfilling techniques as assessedby threemethods. AustDent J 1992;37:439 44.

204. BaileyGC, Cunnington SA,Ng Y-L,Gulabivala K, Setchell DJ.Ultrasonic condensationof gutta-percha: the effect of power setting and activation time on temperature riseat the root surfacean in vitro study. Int Endod J 2004;37:44754.

205. Bailey GC, Ng Y-L, Cunnington SA, Barber P, Gulabivala K, Setchell DJ. Root canalobturation by ultrasonic condensation of gutta-percha. Part II: An in vitro investi-gation of the quality of obturation. Int Endod J 2004;37:6948.

Review Article



13/15

206. Schilder H, Goodman A, Aldrich W. The thermomechanical properties of gutta-percha.Part V. Volume changes in bulk gutta-percha as a function of temperatureand its relationship to molecular phase transformation. Oral Surg Oral Med OralPathol 1985;58:28596.

207. West LA,LaBountyGL, Keller DL.Obturation quality utilizing ultrasonic cleaning andsealer placement followed by lateral condensation with gutta-percha. J Endod1989;15:50711.

208. Stamos DE, Gutmann JL, Gettleman BH. In vivo evaluation of root canal sealerdistribution. J Endod 1995;21:1779.

209. Witherspoon D, Ham K. One-visit apexification: technique for inducing root-end

barrier formation in apical closures. Pract Proced Aesthet Dent 2001;13:45560.210. Lawley GR, Schindler WG, Walker WA, Kolodrubetz D. Evaluation of ultrasonicallyplaced MTA and fracture resistance with intracanal composite resin in a model ofapexification. J Endod 2004;30:16772.

211. Aminoshariae A, Hartwell GR, Moon PC. Placement of mineral trioxide aggregateusing two different techniques. J Endod 2003;29:67982.

212. Sumi Y,Hattori H, Hayashi K,Ueda M. Ultrasonic root-end preparation:clinical andradiographic evaluation of results. J Oral Maxillofac Surg 1996;54:5903.

213. Carr G. Surgical endodontics. In: Cohen S, Burns R, eds. Pathways of the pulp, 4thed. St. Louis: Mosby; 1994:546552.

214. SutimuntanakulS, Worayoskowit W, Mangkornkarn C. Retrogradeseal in ultrason-ically prepared canals. J Endod 2000;26:4446.

215. Keller U. Aluminiumoxide ceramic pinsfor retrograderoot filling: experiences witha new system. Oral Surg Oral Med Oral Pathol 1990;69:73742.

216. Pannkuk TF. Endodontic surgery: principles, objectives and treatment of posteriorteeth: Part I. Endod Rep 1991;6:814.

217. Carr G. Advanced techniques and visual enhancement for endodontic surgery.Endod Rep 1992;7:6.9.

218. Pannkuk TF. Endodontic surgery: the treatment phase and wound healing: Part II.Endod Rep 1992;7:149.

219. Fong CD. A sonic instrument for retrograde preparation. J Endod 1993;19:3745.220. Gutmann JL, Pitt Ford TR. Management of the resected root-end: a clinical review.

Int Endod J 1993;26:27383.221. Wuchenich G, Meadows D, Torabinejad M. A comparison between two root end

preparation techniques in human cadavers. J Endod 1994;20:279 82.222. Waplington M, Lumley PJ, Walmsley AD, Blunt L. Cutting ability of an ultrasonic

retrogradecavitypreparationinstrument.EndodDent Traumatol1995;11:17780.223. Devall R, Lumley P, Wamplington M, Blunt L. Cutting characteristics of a sonic

root-end preparation instrument. Endod Dent Traumatol 1996;12:969.224. BertrandG, FestalF, Barailly R. Useof ultrasound in apicoectomy.Quintessence Int

1976;7:912.225. Flath RK, Hicks ML. Retrograde instrumentation and obturation with new devices.

J Endod 1987;13:5469.226. von Arx T, Walker WA. Microsurgical instruments for root-end cavity preparation

followingapicoectomy:a literature review. Endod DentTraumatol 2000;16:4762.227. Kim S, Kratchman S. Modern endodontic surgery concepts and practice: a review.

J Endod 2006;32:60123.228. Gutmann JL, HarrisonJW. Posteriorendodonticsurgery: anatomicalconsiderations

and clinical techniques. Int Endod J 1985;18:834.229. Kim S. Principles of endodontic microsurgery. Dent Clin North Am 1997;41:

48197.230. Kellert M, Solomon C, Chalfin H. A modern approach to surgical endodontics:

ultrasonic apical preparation. N Y State Dent J 1994;60:258.231. Rubinstein R, Torabinejad M. Contemporary endodontic surgery. J Calif DentAssoc

2004;32:48592.232. Mehlhaff DS, Marshall JG, Baumgartner JC. Comparison of ultrasonic and high-

speed-burroot-endpreparationsusing bilaterally matched teeth. J Endod 1997;23:44852.

233. Gutmann JL, Saunders WP, Nguyen L, Guo IY, Saunders EM. Ultrasonic root-endpreparation: Part 1. SEM analysis. Int Endod J 1994;27:318 24.

234. EngelTK, Steiman HR. Preliminary investigation of ultrasonic rootend preparation.J Endod 1995;21:4435.

235. Gorman MC, Steiman HR, Gartner AH. Scanning electron microscopic evaluationofroot-end preparations. J Endod 1995;21:1137.

236. Lin CP, Chou HG, Kuo JC, Lan WH. The quality of ultrasonic root-end preparation: aquantitative study. J Endod 1998;24:66670.

237. Khabbaz MG, Kerezoudis NP, Aroni E, Tsatsas V. Evaluation of different methods forthe root-end cavity preparation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod2004;98:23742.

238. Abedi HR, Van Mierlo BL, Wilder-Smith P, Torabinejad M. Effects of ultrasonicroot-end cavity preparation on the root apex. Oral Surg Oral Med Oral Pathol OralRadiol Endod 1995;80:20713.

239. Rud J, Andreasen JO, Moller-Jensen JE. A follow-up study of 1000 cases treated byendodontic surgery. Int J Oral Surg 1972;1:1528.

240. Amagasa T, Nagase M, Sato T, Shioda S. Apicoectomy with retrograde gutta-percharoot filling. Oral Surg Oral Med Oral Pathol 1989;68:33942.

241. Tidmarsh BG, Arrowsmith MG. Dentinal tubules at the root ends of apicected teeth:a scanning electron microscopic study.

ultrasonics in endodontics - a review of literature

Documents