Internai ion J i Coiiege of Prosthodortisls

The Eighth Meeting of the International College of ProsthodontistsStockholm, Sweden

luly 7-10, 1999

Co-Chairmen: Dr Terry Walton and Professor Brian Monteith

Poster Presentation AbstractsThe abstracta for (he Poster Presentations sre in tilphabetical order ijy the firsl auliior's last name. Focus and Short Paper Session

abstracts were published m the previous, issue of the journal (Volume 12, Number 5, 1999).

T. AbdelHalim, M. El-Sibaie, 5. Campbell,Chicago, IllinoisInternal Dimensional Changes During Settingo/Oentai Casling Investment

Tiie flimensionai changes that occjr internallyduring the setting ot dentai casting investmentare rot fully understood. Emsting studies haveeither used external measurements ol expan-sion or have not inciiided a wax pattern as partot the exprimentt design. The puipose of thisstLidy was to e!

International College of Prosthodontists

Ectndermai dyspiasia is a syndrome character-ized in the oral qaviry by the partiai or total lackot dental elements. Ttiis presents the clinicianwith the problem o rehabilitating the patient'smoulhfiorr an early age This clinical report fol-lows a completely edentulous palient from ttieage of 41 to 9, The problems ot a case siioti asthis one are technical because ol difiicjities inrealizing a total prosthesis in the uery young pa-tient. There are also biologic and psychologicproblems because ct (he growth of the patientand subsequent modification of Ihe prosthesis(remaking and realigning ol the bases, the ver-tical dimensions, the choice pf the artificialteeth). The clinical results are appreciable.

S, Catapano, M, Franchi, R. ScottI, Ferrara,ItalyEvaluation of Air Inclusion of IrreversibleHyrocoiioids Mixed with Three DifferentSpatuiation Techniques

The aim of this study was to compare the pres-ence of air inclusion in an irreversible hydrocol-loid mixed with three flifferent techniques: me-chanic, vacuum-mechanic, and rnarual. Threemetal trays, with shape and dimensions pro-posed by StackhcuSB, were used. Ten mixingsgroup A) were executed using Ihe mechanicaldevice Orthora Migma IMikrora), ten (group B|using a Whip Mi vacuum spatulator (Silky-Rock), and ten (group C] manually. The irre-versible hydrocolloid used was the Calginat 3(Pierre Roland), which was miied by the sameoperator. For each impression's Iray, len uniformrectangular sections of 2 mm' were obtainedand putrnan appropriate rectangular card Theywere then photographed and subsequently an.alyzed by a second operator through a com-puterized picture analysis system. The numberol bubbles for group A ranged from 0 to 6 (me-dian 4) with a mean surtace of 0.65 mm^ and anSDot 0,65; the number tor groups ranged from6 tp 15 (median 11 ) with a mean surtace of 5.64mm^ and an SD cf t.27; and the numtier forgroup C ranged trom 29 to 73 (median 42) witha mean surface ot 11.80 mm' and an SD cf 2.The analysis of variance and the test ot Bon-terroni were performed foi the values of surtaceoccupied biy the air bubbles; for the numbei ofbubbles tne Kmskal-Wallis test was pertormed.The irrereisibie hydrocclloids mixed mechani-cally or vacuum mechanically contain inclusionsor air that make them considerably inferior to thehydrocoltoids prepared t>y hand mixing

A. Ctov ic , R, Pol jak-Guber ina, V,Jerolimov, Zagreb, CroatiaDoes Thermai Cycling Affect DynamicStrength Between Ag.p Ailoy andHydrothermal Ceramics?

The failure of the ce ramie-to-meta I interfaceproduces an uncomfoj1at>le situation to/ both thepatient and the clinician. The aim of this studywas to detemiine the dynamic resistance char-acteristics of the interface of hydrothermal ce-ramics (Duceragold, Degussa) and Ag-Pd alloy(ceramduo) Thetestedspecimensoonsistedof metal trames (45 mm x ta mm -: 4 mm)upon which tfie ceramic was fused (25 mm y12 mm y. 2 mm). The specimens were dividedinto 2 groups; the fiist with thermocycled sam-ples (t ,000 times at 0*C and 55C), and the sec-ond group wilh nonthermocycled samples. The3-point dynamic loading test of the sampleswas pertormed in Amsler's high-frequency pui-sator within the loading range ol 550 to 1,200 N.

The obtained results of 85Q N tor the dynamicresistance pointed out that the Duceragold-ce-ramduo system is improved in compaiison to theother ceramometal systems Because otthe rel-atively high obtained values of the dynamic re-sislance. The thermocyciing significantly low-ered the dynamic resistance of Ihe testedsyslem [P < 0.05), The thermocycled samplesexhibited tailureoftheceramomelal interlace at30% to 50% tewer eye les for the same dynamicloading values in comparison with the ncnther-mocycled samples. This finding suggests thatthe sudden temperature ohanges in the oralcavity can significantly shorten the life span andthe durabiiity of this metal ceramic.

H, Cho, J, Lee. T, Jin. Iksan, South KoreaA Sludy on the Fracture Strength and Strain ofImplant Restoration Using Ceramic Abutmentand All-Ceramic Crown

All-ceramic abutments and crowns have be-come an attractive altemative to metailic im.piant prostheses, but their strength and stresstransfer needs more documentation The aimof the present study was to compare ditferentabutment-crown combinations lor single-im-plant restoration and, as a control, a conven-tional metal-ceramic crown cemented on theCeraOne abutment (Nobel Bicoare). CeramicaOutments were copy milled from the CeraOneabutment using the In-Ceram sintered aiuminablocks (Vident) The ceramic crowns weremilledwithln-CeramandCelay feldspar blocks.Design groups were: (1) In-Ceram crowns ce-mented on the CeraOne abutmeni, (2) Delayleldspar crowns cemented on the CeraOneabutment, (3) Ir-Oeram orowns cemented onIhe ceramic abutment, and (4) Celay leldsparcrowns cemented on the ceramic abutment, A10-mm-long Brnemark implant (NobelBiocare) was placed into a resin block and therestoration was cemented to the implant. Tnespecimen was loaded at 0- and 45-degree an-gles tc the long axis, and the load values at themoment of tracture were recorded using anInstron machine. Two rosette gauges wereplaced 2 mm latiial and lingual to the implant,and strain indicator readings were recordedunderuerticaiandoblique loading at 100N Thefradure strength of the ceramic abutment wassomewhat lower than expected. There was nosignificant difiere nee between the Iracturestrength oi the In-Ceram and Ceiay teldsparcrowns on the ceramic abuiments or among thefracture strength oi the three ditferent crownson the conventional CeraOne atjutment. Onoblique loading, ceramic crowns usmg the ce-ra mrc abutment showed iower fracture strengththan the conventional CeraOne abutment. Theweakest portion oi crowns using the CeraOneabutment on oblique loading was the abutmentscrew, and the briltie iracture of the ceramicabutment was shown on oblique leading. TheStrain on the supporting tissue was higher withoblique loading than with uertical loading, andthe highest compressive stress was measuredon the labiai side oi the implant restoration onoblique loading.

Y, Ciltci, S, Canay, Ankara, TurkeyThe Effect of Stress Distribution of theVeneering Materiais on the Implant-SupportedFixed Prosthetic Restorations

in this study the effeot of various rnaterials usedin fabricating implant-retained fixed partial den-tures on stress distribution around peri implant

tissues was investigated. Five different malhe-matic models consisting of 11 361 nodes and54,59 elements were constructed lo studyporcelain, metal, composire resin, relntorcedcomposite resin, and acrylic resin veneeringmaterials using a three-dimensionai finite eie-ment stress analysis method. MARC K7,2/Mentat 3.2 (MARC Analysis Research] stressanaiysis software was used for the analyses.Reference points were determined on corticalbone, where perpendicular, oblique, and hori-zontal forces were applied. Stress values cre-ated by oblique and horizontal forces appearedto be higher thah those created by verticalforces Stress seemed to concentrate at thecortical bone around the cervicai region of theimplant Melaland porcelain produced the high-est stress values in this region. Stresses createdby acrylic resin and reinforced composite resinwere 25% and 15% lower, respectively, com-pared 10 porcelain and metal. Porcelain andmetal produced stress values at the lingual im-plant sites reaching the ultimate stress valuesof cortical bone.

E, Conserva, P. Pagl lar i , D, Chembrl,Alb eng a, ItalyComposite-Fissk: A New System for Light-Curing Materiais ih Prosthodontics

The Composite-Flask (Ribas) is an innovative,transparent acryiic glass flask that, with respectto the common manual technique used to makeprosthetic restorations with light-curing materi-als, gives us the iollowing advantages: (1) aconstant and homogenous compression of thecomposite material also on a melal framework;2) Ihe photopolymerization occurs in lack oioxygen so that the composite surface will bevery compact and glossy: and (3) in the case oia metal-composite resloration. we can check thetooth shape, trying the wax pattern direcUy in themouth ot Ihe patient. The aim ot this work wasto verify these statements. We made 12metal-composile single crowns using the Diamond-Crown liglit-ouring material (DRM Laboratories),6 using the transparent tiask and S using thecommon manual technique. We quantified thedegree oi photopolymerization and ihe amountof waler sorption, and then each restorationwas sectioned by a faser machine and scanningeledron microscopy (SEM) analysis was per-formed. The analysis oi the degree ot pho-topolymerization (dual-band technique) showed100% polymerization in all specimens. Theanalysis of the water sorption (specimens im-mersed in 37C water for 7 days and weighedby an analytio Giberiini balance) showed no in-crease in volume of the specimens There wasa 0 03% mean increase in volume oi the spec-imens made using ihe oommon manual tech-nique. The SEM analysis (LEO 420) revealedthat the restorations made using the Iranspar-ent ilask showed better adhesion betweenopaque and composite, iess internal porosity,and betler surtace compactness.

E. Conserva, F, Pagl lar i , D. Chembri ,Albenga, ItalyDiamond Crown Composite Resin: A NewLight-Curing Materiai for Restorative andProsthetic Dentistry

Diamond Crown composite resin (DHMLaboratories) is a light-curing materiai com-posed of an epoxy-phenoiic; t is a silica-filledglass-ceramic with a orystalline microstriic-ture. Its physical and mechanical properties

The International I of Proithodontics 556 Volume T2, Number

International College of Prosthodontists

are: Youngs modulus (E)^2-\ ,0D0 MPa: com-pressive strengtb = 552 MPa; liexural strengthT 231 MPa: water sorption = 0.35%: wear < 3|jm/y; diametral tensile strength = 79 MPa:poiymerization shrinkage = 0,20%; and depthot proiymerizatlon = 5 5 mm This material canbe used lor (1) direct and indirect anterior/pos-terior teetti restorations, (21 repairing resin orceramic crowns, (3/ metal-composite crownsor bridges, (41 metal-free composite crowns or3.unit bridges. (5JendodQnticaiiy treated teethrestored with posts, and (6) custom teeth tordentures. Twenty-one consecutive meta!-com.posite crowns were placed in B patients with amean age ot 50.S years, and 25 ocnsecutivemetal-iree crowns were piaced in t9 patientswilh a mean age o 39.1 years. Crowns weremade witti the Composite-Fiasii procedure(Ribas) in a 6-month period. The crowns wereevaiuated using the CaiiFornia DentaiAssociation (CDA) quality assessment evaiu-ation system 1 month aftercemenlation and at1 year. At tbe 1-year recaii 20 ot the originai 21metal-composite crowns and 23 ot the originalS5 metal-free composite crowns could be euai-ualed. No statislicaify significant difterencesin CDA scores between the 1-monlh and 1-year assessments were tound tor surface andcolor, anatomic form, or marginal Integrity. TheDiamcnd Crown composite system could pro-duce quality witb or without metal, especiallyif used with a transparent ccmposite tiash.

H, Denissen, Amsterdam, The NetherlandsProcura Onlays: A Preliminary Report

The favorable periodontal, functional, and ma-terial aspects ot cast gold onlays are well ioiown.IHowever, major drawbaciis have been the colorof gofd and the hand-made production. Proceracomputer technology (Nobel Biocare) has en-riched dentistry with new ways of producingstrong AljOj complete-crown copings. We teitthatitalsowouid be advantageous (oronlays tocombine a Procera-produced coping veneeredwith porceiain. Maxillary and mandibuiar moiarswere prepared wrth an occlusai seat and deepgingival chambers rn the proximal boxes andaround the functional cusps (buccal of mandibu-iar and paiatal of maxiiiary teeth). The nonfunc-tional cusps {lingual ot mandibular and buccai ctmaxillary leelh) were prepared wiBi broad bevefstollowing tlie inclined occlusal plane pattem.Hydrocolioid impressions were taisen and sifongdies were produced. The surfaces of the dieswere scanned with the contact probe, and thedata produced the interrordesfgn ofthe copings.Tfie exterior design ot the copings was createdbyscanning wax copings. Asphericai phantomwas scanned as well, and cup-shaped copingswere made as controls. The AI^O^ copings wereporcelain veneered for optfmLZing tit, function,and esthetics. After cementation oitheoniayinthe mouth of Ifie patient, a hydrocolioid impres-aon was taken and a stone model was pro-duced. The marginal cement width on the stonemodef was calcufaled by microscopic digitaimeasurements. Onlay preparations were com-plex surfaces for computer surface digitizationby the Procera scanner probe. The die had tc bealigned to the scanner in such a way that no in-terference with the probe holder occurred. Theinner angies of the seat and Ihe boxes had to berounded by applicafcn of dental wax, and theseregions had to be veneered iater with corebuildup porcelain material to optimize internal TitThe mean marginal gap ot ihe onlays on thestone dies was 68 pm (SD 53). The mean

cement width on the stone model was 81 pm(SD 64) The cosmetic aspect and the functionof the onlays were eiceiient because o thepoiceiain veneenng. Ttie aim ot this study wasto delemiine whether the Procera system iscompatible with a proposed onlay design andcapable ot producing AI^O^ copings. Our re-sults for marginal fit of onlays compare weli willittiose reported for Procera complete crowns.Nevertheless, crattsmanship was necessary tooptimize tit by intemal and marginal porceiain ve-neering to obtain a mean cement width of 8t |im.

, Desaki, V, Tanaka, , Nakamura, Nagoya,JapanDevelopment of New Reintorced ArtificialResin Teeth Specialty Designed for aRemovable Partial Denture and a MagneticAttachment

Magnetic attacbments were tirst introducen inioJapanese dentistry in 1992, At Ihe last ICPmeeting in Malta, we showed various clinicaicases indicating that complete and paiiai over-dentures with magnetic attachments aie a veryusetui clinicai approacb, especialiy for a patientwith only a limited number of remaining feelh.Although a magnetic denture is marvelous, it stiilcreates some ci mica i probiems. These concemartificia i teeth. Today, reinforced resin teeth arepopular for dentures because of their eicellenlabrasive resistance. But wtien rt comes to theiruse in magnetic dentures, an excessive scrap-ing of the tooth bottom is oflen necessary. Thiscauses a fracture of the artificial teeth By ioos-ening the thin iayer of acrylic resin provided atthe bottom to secure adhesion to the denturebase. We have recently developed new arWcialteeth that are intended for use with magnetcdentures. The new reinforced resin leelh havea unique scooped bottom shape tbat mal