Dental Research Journal

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1 Dentl Reserch Journl Clinicl Report All cermic prosthetic rehilittion of worn dentition: Use of distl cntilever. Two yer follow up Usm N. Chekhni 1, Aikterini A. Mikeli 1 *, Fin K.P. Huettig 1 1 Deprtment of Prosthodontics nd Section of Medicl Mterils nd Technology, Center of Dentistry, Orl Medicine nd Mxillofcil Surgery, University Hospitl Tueingen, Tueingen, Germny Received: June 2012 Accepted: Octoer 2012 Address for correspondence: Dr. Usm Chekhni, Deprtment of Prosthodontics, Dentl School, Osinderstrsse 2 8, Tueingen, D 72076, Germny. E mil: usm.chekhni@ med.uni tueingen.de *Aikterini A. Mikeli sserts equl contriution nd joint first uthorship. ABSTRACT The rehilittion of hevily rded occlusion in ptients with prfunctionl hits is restortive chllenge to the dentist. Use of ll cermic systems in such cses is widely considered, ut uncertinty over their resistnce hinders their rod use. The uthors would like to illustrte possile pproch y mixing two ll cermic systems sed on zirconium dioxide nd lithium disilicte. A 48 yer old femle ptient ttended with reduced verticl dimension in full dentition. She suffered from crniomndiulr (CMD) pin nd desired n esthetic rehilittion. Prosthodontic tretment ws strted in pin free condition, fter correction of the verticl dimension with n occlusl splint, over four months. Determintion of the tretment ws sed on the clinicl findings: IPS e.mx ZirCAD frmeworks veneered with IPS e.mx Cerm were used for discolored retiners or sugingivl finishing lines. All the rest received IPS e.mx Press crowns. A zirconi sed, single tooth retined distl cntilever reconstruction ws used to replce missing second molr. No technicl or iologicl compliction ws oserved 24 months fter tretment. The ptient ws highly stisfied nd pin free. Key Words: Computer-ided design/computer-ided mnufcturing, ll-cermic, multilink, relyx Unicem INTRODUCTION The development nd use of ll cermic systems in prosthodontics ws driven y the need for estheticlly improved nd more iocomptile mterils compred to trditionl metl sed prostheses. Nowdys, lrge choice of cermic mterils with different mechnicl properties nd esthetic performnce re ville. However, there is no evidence supporting the ppliction of one, single cermic mteril in every clinicl sitution. [1] Selection of the most suitle ll cermic system for ptient, mtching introrl conditions nd esthetic requirements, is highly demnding nd chllenging procedure. Access this rticle online Wesite: All cermic systems cn e divided sed on the presence of cermic core. [2,3] Coreless systems re fricted completely from specific cermic mteril (monolithic), such s, lithium disilicte glss cermic IPS e.mx Press (Ivoclr Vivdent, Schn, Liechtenstein). Core systems use cermic frmework, chrcterized y high frcture toughness nd veneered with estlished porcelin, to simulte the esthetics of nturl tooth. [2] Frmeworks re mostly fricted y computer ided design/computer ided mnufcturing (CAD/CAM) systems from yttrium stilized tetrgonl zirconi polycrystls (Y TZP), nd in the cse of IPS e.mx ZirCAD (Ivoclr Vivdent), covered y hydrotherml veneering cermic (IPS e.mx Cerm, Ivoclr Vivdent). Due to trnslucency, monolithic ll cermic restortions reproduce the nturl ppernce of the tooth efficiently. [2,4] At present, gret rnge of opcities, trnslucencies, nd shdings of silicte cermic re ville. Technicins use pint techniques (externl 126 Dentl Reserch Journl / Jnury 2013 / Vol 10 / Issue 1

2 color ppliction) for further customiztion. However, ecuse of its inferior mechnicl properties it is only recommended for nterior or posterior single crowns nd mximum three unit, short spn, nterior fixed dentl prostheses (FDPs). [5] High strength oxide cermic (core systems) is the preferred mteril for posterior nd/or multiple FDPs. [6,7] According to Sundh et l., [4] Y TZP cermics exhiit n excellent mechnicl performnce nd frcture resistnce compred to other cermics. As reported y Studrt et l., [7] prtilly stilized zirconi cn withstnd the lods typiclly pplied in the molr region, providing flexurl strength greter thn 900 MP. On ccount of its high mteril stility nd iocomptiility, zirconi offers vlule lterntive to metl. [8] However, the mostly white nd opque frmework crries n esthetic disdvntge. [9] Nevertheless, in cse of discolored utments this cn turn into n dvntge, too. The most common clinicl compliction of these restortions is the veneering porcelin frcture (chipping), with rte lmost 50% higher thn tht of the porcelin fused to metl (PFM) reconstructions. [10,11] Furthermore, the success of these systems depends on the ond strength etween the core nd veneer cermic, while unfvorle sher forces in etween cn influence their long term interction. [12] Another known reson is the missing support of the veneering lyers, ecuse of indequte frmework design. [11,12] Y TZP frmeworks themselves feture peerless mteril property: Active crck resistnce, known s trnsformtion toughening. [1,4,6,10,12] This Y TZP trnsformtion effect, [1,6,10,12] providing retrded crck propgtion, prevents filure nd is criticl fctor for clinicl success. However, drwck of ll cermic mterils is their susceptiility to ftigue mechnisms, which cn considerly reduce their initil strength, over time. The mstiction forces cn rech 250 N, while the forces due to clenching/grinding cn rech up to 800 N. [13] Therefore, the rehilittion of hevily rded occlusion on ptients with prfunctionl hits nd/or specil design fetures, such s cntilevers nd wide spns, is considered to e contrindiction for ll cermic restortions. [1] In vitro studies, s lredy referred to, support the use of high toughness cermics s frmework mterils for posterior ll cermic FDPs. Potiket, et l. [14] suggest tht there is no significnt difference in the frcture strength etween ll cermic nd metl cermic restortions. The frcture resistnce of cermic core mterils is ffected minly y the connector design. A minimum connector height of 3-5 mm from the interproximl ppill to the mrginl ridge is guideline for most ll cermic systems. This provides minimum connection surfce of pproximtely 9 mm 2, which is considered to e pproprite for three unit FDPs. [5,12,14] Gert et l. [9] found cceptle frcture lod vlues for ll cermic cntilever FDPs with Y TZP frmework replcing one premolr, when the end utment received full crown. Groten et l. [11] lredy descried successful ll cermic posterior cntilevered rehilittion, with three yer follow up. With respect to the frmework design of the ll cermic cntilever FDPs, 16 mm² connector cross section etween the utment nd premolr sized cntilever is idelly desired. [5] The following cse illustrtes the restortive nd esthetic potentil of two different ll cermic systems under chllenging conditions s lterntive to the stndrd PFM reconstructions. A femle ptient with reduced verticl dimension, suffering from recurrent mild crniomndiulr pin, desired n esthetic, nd if possile, metl free restortion, due to her mild llergy towrd nickel. Clinicl report A 48 yer old femle cme to the Prosthodontics Amulnce of the Dentl Clinic, t the Tueingen University Hospitl. She suffered from recurrent mild pin on oth sides of her mndile. She sked for complete prosthetic tretment with focus on esthetics nd reported to e llergic to cetyl slicylic cid nd nickel. Exmintion Chewing s well s neck nd shoulder muscles were pinful on plption. The temporomndiulr joint ws pin free on plption nd movement, without disk derngement. The introrl exmintion reveled n Angle s clss I, deficient verticl dimension of occlusion (VDO), ruxo fcets on the posterior teeth, nd rsion on the nteriors. The orl hygiene ws very good. Physiologicl proing depths etween 2 nd 3 mm were detected, except in the upper left second molr, which hd perio endodontic lesion with proing depths of 6 mm mesil nd 9 mm distl [Figure 1]. The third molrs were missing. The upper left first premolr nd first nd second molrs were restored Dentl Reserch Journl / Jnury 2013 / Vol 10 / Issue 1 127

3 with metl cermic crowns, with visile nd decyed suprgingivl mrgins. The lower right second molr ws restored with metl crown. Other mxillry teeth nd the mndiulr premolrs, second left molr, nd the first right molr hd composite fillings. Cries nd/ or secondry cries were detected in the mxillry left centrl incisors, the right cnine, right second premolr, nd first molr. On the mndile, the right nd left first nd the left second molr teeth were lso decyed. Only the mndiulr nteriors were in completely helthy condition. Rdiogrphic exmintion reveled endodontic tretment t the upper left second incisor nd the upper left first molr [Figure 2]. Bsed on the dignosis, insufficient prosthetic restortion on deficient verticl dimension of occlusion (VDO) nd considering the ptient s wish for esthetic restortion, the following two stge tretment ws suggested: Preprosthetic conservtive tretment, extrction of the mxillry left second molr, nd splint therpy for VDO increment. Next, n ll cermic, full rch mxillry restortion, with single crowns, ws performed. A decision ws mde to restore the mndiulr teeth, except the centrl nd lterl incisors, with ll cermic single crowns. An lterntive tretment possiility (not followed in this cse) involved the stndrd metl cermic restortion. The ptient gve preference to the first metl free, more esthetic vrint. Phse 1: Preprosthetic tretment The conservtive preprosthetic tretment included the endodontic retretment of the mxillry left first molr. The decyed fillings were replced with Tetric EvoCerm using the cid etching technique under reltively dry conditions with the Syntc Helioond System (Ivoclr Vivdent). A cermic post ws plced (CosmoPost, Ivoclr Vivdent) in the mxillry left lterl incisor, luted with dhesive resin cement (Multilink Automix, Ivoclr Vivdent), nd uilt up with universl nnohyrid composite (Tetric EvoCerm, Ivoclr Vivdent). The mxillry left second molr ws extrcted due to infust prognosis. Irreversile hydrocolloid (Blueprint Cremix, Dentsply DeTrey, Konstnz, Germny) impressions of oth jws were tken with rim lock impression trys t the first ppointment. Beuty pink (Moyco Union Broch, PA 17402, York, USA) ws used for ite registrtion. The dignostic csts were rticulted using fce ow trnsfer of the Rotofix System (Amnn Girrch, Kolch, Austri). Next, the cst nlysis determined the required spce for the restortion nd consequently the VDO increment. An extr 3 mm from the tips of the incisors ws necessry, which ws dded t the incisl pin of the rticultor. In this position removle mndiulr crylic occlusl splint ws mde, which ws inserted, to test the new VDO position cliniclly. From our clinicl experience the mndiulr splints were esier for the ptient to ccept compred to the mxillry splints. The ptient wore this occlusl splint 24/7 (twenty four hours dy/seven dys week). One month lter the ptient cme for control. Muscle nd temporomndiulr joint (TMJ) rection to the incresed VDO were cliniclly exmined. No dverse effects were reported or detected [Figure 3]. As the lst prt of the preprosthetic phse, the old crowns were crefully removed. Due to the indequte remining clinicl crown, titnium post (Unimetric #210, Dentsply DeTrey) luted with composite (FlexiFlow, Essentil Dentl Systems Inc., Hckensck, NJ, USA) ws used to restore the mxillry left first molr core. An utopolymerized composite ws used for the core uild up of the mxillry left first premolr nd molr, nd mndiulr right second molr (Ti Core Nturl, F Nordent c Figure 1: Initil dentl sttus d e Figure 2: Preopertive sitution () Right side () Frontl view (c) Left side (d) Occlusl view, mxill fter endodontic retretment of the mxillry left first molr nd extrction of the mxillry left second molr (e) Occlusl view of the mndile (f) Rdiogrphic exmintion f 128 Dentl Reserch Journl / Jnury 2013 / Vol 10 / Issue 1

4 Inc., Mississug, Cnd). The ptient remined under regulr control for the next three months. The ptient s positive feedck from the new verticl dimension s well s the pin free jw muscles, llowed the second phse prosthetic restortion. Phse 2: Prosthetic tretment To implement the functionl sitution of the splint to the finl condition, mxillry full rch nd mndiulr prtil rch restortion ws necessry. New dignostic csts nd new rticultion, using fce ow trnsfer, ite registrtion, nd dignostic wx up were mde in the new VDO. This ckwrd plnning llowed control of the esthetic results nd re evlution of the ville spce for restortion. A comintion of IPS e.mx ZirCAD (zirconium oxide for the CAD/CAM technique veneered with IPS e.mx Cerm) nd IPS e.mx Press (lithium disilicte glss cermic for the press technique) ws chosen with regrd to the different grdes of decy nd discolortion. For ll the teeth needed to e restored, full crown design ws plnned, except prtil crowns for the mndiulr cnines. The mxillry left first molr ws plnned to e full crown with distl cntilever, to void elongtion of the ntgonist. A two unit, cntilevered FPD ws designed, to eliminte the consequences of potentil filure, either ecuse of the doutful prognosis of the endodontic treted utment tooth or the ll cermic cntilever. A possile future utment loss or connector frcture would not set into risk the whole restortion. IPS e.mx ZirCAD ws ssigned to the teeth tht were discolored or where the sugingivl finishing lines were expected, nd to the cntilever whose reconstruction hd to e supported y zirconium frmework. More specificlly, the teeth restored y IPS e.mx ZirCAD were the mxillry right second premolr nd molr, left first premolr, first nd second molrs, nd mndiulr right second molr. A mm chmfer ws prepred t the finishing line, wherever possile, prmrginlly, for the IPS e.mx Press restortions. An eight to ten degree ngle of convergence ws used for the preprtion nd ll the shrp edges were rounded nd smoothed. The occlusl reduction, fter VDO increment, ws 1.5 mm, to ensure sufficient room for the porcelin. The provisionl restortion ws mde chir side with the id of polyethylene foil (Erkodur C, F. Erkodent, Pflzgrfenweiler, Germny). This ws mde on duplicted cst from the dignostic wx up. Therefore, the mxillomndiulr reltionship could e djusted t the finl VDO. Bis GMA sed Protemp 3 Grnt (3M ESPE, Seefeld, Germny) ws used s the provisionl restortion mteril. Temporries were luted with eugenol free provisionl cement (Temp Bond NE, F. Kerr, Slerno, Itly) [Figure 4]. The functionl nd esthetic prmeters were optimized within the provisionl phse. Lter this sitution ws trnsferred to the finl restortion. The single cord technique (#1 in nterior re nd #2 in the posterior re, Retrco, F. Roeko, Lngenu, Germny) ws used for preprtion of the impressions on ll teeth, excluding the prtil crowns. The cords were imued with hemosttic solution nd gingivl retrction (Rcestyptine, F. Septodont, Sint Mur Des Fosses, Cedex, Frnce) [Figure 5]. Impressions were tken with polyether (Impregum, Pent, nd Permdyne Grnt 2:1, 3M ESPE) using n individulized rimlock try nd doule mixing technique. The impression compound (Kerr, West Collins, Ornge, CA, USA) ws used for Figure 3: Mndiulr splint on rticultor, frontl view Figure 4: Temporry restortions Dentl Reserch Journl / Jnury 2013 / Vol 10 / Issue 1 129

5 Chekhni, et l.: All cermic rehilittion of worn dentition ite registrtion under contrlterl support of the temporries. Fce ow trnsfer ws gin done with Rotofix. The IPS e.mx Press crowns of high trnslucency were fricted y the hot pressing technique. IPS e.mx ZirCAD ws ville from the mnufcturer s zirconium oxide locks, for the CAD/CAM technique. The IPS e.mx ZirCAD frmeworks were veneered with IPS e.mx Cerm (fluorptite veneering cermic). Specil cre ws given to the connector design of the single retined cntilever. The cross section ws 16 mm2, to withstnd the lter mstiction forces. The fitting of the definite crowns were first controlled on the csts nd then were tried introrlly, with the id of fine proe nd Occlu Spry (Hger nd Werken, Duisurg, Germny). The esthetics nd occlusion were lso controlled. After the finl corrections in occlusion, form, nd shde, the restortions were glzed. Adhesive resin cement (Multilink Automix, Ivoclr Vivdent) ws used for dhesive luting of ll crowns, ccording to the mnufcturer s instructions. The cntilevered crown, ecuse of the sugingivl preprtion line, ws luted with RelyX Unicem (resin modified glss ionomer luting gent, Unicem Trnsprent, 3M ESPE) [Figure 6]. After completion of tretment, the ptient received new occlusl splint. The ptient cme for 1, 3, 6, 12, nd 24 month control. Neither technicl nor iologicl complictions were oserved 24 months fter tretment. The ptient ws highly stisfied nd free from pin [Figure 7]. DISCUSSION Ptients with rded occlusion nd prfunctionl hits re chllenge to ny dentist. These rehilittions require time nd multi stge procedure. The first phse includes VDO re estlishment; necessity deriving from the need for esthetic improvement of the lower fce[15] nd the need of the required spce for the restortion. Restortive tretment of ptients with indequte lower fcil height is importnt, ecuse of its effect on the long term physiologicl function of the chewing muscles. Strting with splint therpy, clinicins test the ptient s cceptnce of the new VDO. Neuromusculr dpttion tkes plce out three to four weeks fter VDO increment.[15] Unprolemtic mstictory function, reduced CMD pin, nd the 130 ptient s cceptnce of this new VDO position re prerequisites for the next tretment stge definite restortion. In our cse, the ptient remined under splint therpy nd regulr recll for 16 weeks, for greter certinty. Temporry restortions mde in this new VDO llowed doule checking of this position. The tretment pln included single crowns for ll utment teeth, to ensure esy repir utment of the teeth, with high esthetic vlue, nd slightly suprgingivl or equigingivl mrgins were restored y lithium disilicte glss cermic (IPS e.mx Press). The ville trnslucencies nd opcities rendered this mteril idel for esthetic restortions. Moreover, monolithic lithium disilicte restortions minimized Figure 5: ( nd ) Mxill mndile preprtions c d e Figure 6: Definitive finl restortions () Occlusl view of the mxill () Occlusl view of the mndile (c) Right side (d) Frontl view (e) Left side c d Figure 7: Two yer follow up () Smile line () Frontl view (c) Mxill nteriors (d) Rdiogrphic exmintion Dentl Reserch Journl / Jnury 2013 / Vol 10 / Issue 1

6 the chipping hzrd often oserved y veneered zirconi. For discolored utments the opque zirconi system ws chosen (IPS e.mx ZirCAD). In ddition, the zirconi frmework ws used for the cntilever ridge. Zirconi frmeworks showed the est mechnicl properties nd should e preferred when extreme mechnicl lod is expected. [4,6,8,11,12,14,16] The cementtion protocol of ll cermic restortions is essentil for success. [6] Clinicins cn effectively etch silic sed cermics for dhesive onding, which increses the frcture resistnce significntly. [3] In contrst, zirconi cnnot e etched nd onded in this mnner. According to the mnufcturer s instructions IPS e.mx ZirCAD nd the IPS e.mx Press restortions cn e either conventionl or dhesively luted. In this cse, we used low viscosity composite resin cement (Multilink Automix, Ivoclr, Vivdent) for ll crowns, except for the cntilever zirconi sed crown t the mxillry left first molr. The sugingivl mrgins of this crown, comined with its posterior topogrphy in the rch, mde proper isoltion required for dhesive cementtion lmost impossile. RelyX Unicem hs miniml moisture nd contmintion tolernce nd is furthermore cement of choice for zirconi ll cermic restortions. As concluded y Groten nd Huttig, [17] filures of zirconi sed restortions re relted to iologicl events such s ruxism. For prevention of chipping fter rehilittion it is suggested tht the ptient pply n occlusl splint t night. CONCLUSION A comintion of the current ll cermic mterils enles the dentist to tret ptients with prfunctionl hits nd rded occlusion. The selection of the mteril must e lnced etween the esthetic nd strength requirements, s well s, mode of cementtion. The lithium disilicte cermic ppers to e vlid lterntive for stle superior esthetic results for single tooth crowns. Zirconi sed solutions must e used for multi unit nd prticulr restortions, such s distl cntilevers. Nevertheless, more clinicl experience is necessry. REFERENCES 1. Conrd HJ, Seong WJ, Pesun IJ.Current cermic mterils nd systems with clinicl recommendtions: A systemtic review. J Prosthet Dent 2007; 98: Shirkur A, Lee H, Geminini A, Ercoli C, Feng C. The influence of veneering porcelin thickness of ll cermic nd metl cermic crowns on filure resistnce fter cyclic loding. J Prosthet Dent 2009; 101: Kelly JR, Nishimur I, Cmpell SD. Cermics in dentistry: Historicl roots nd current perspectives. J Prosthet Dent 1996; 75: Sundh A, Molin M, Sjögren G. Frcture resistnce of yttrium oxide prtilly stilized zirconi ll cermic ridges fter veneering nd mechnicl ftigue testing. Dent Mter 2005;21: Kern M, Kohl RJ, Pospiech P, Frnkenerger R, Reiss B, Wiedhhn K, et l. Vollkermik uf einen lick.4 th ed. Ettlingen: AG für Kermik in der Zhnheilkunde; Gmoren I, Bltz MB. Comprehensive nd functionl rehilittion with CAD/CAM ll cermic system. Quintessence Dent Technol 2007;30: Studrt AR, Filser F, Kocher P, Lüthy H, Guckler LJ. Mechnicl nd frcture ehvior of veneer frmework composites for ll cermic dentl ridges. Dent Mter 2007; 23: Siler I, Zemic A, Jung RE, Siegenthler D, Holderegger C, Hämmerle CH. Rndomized controlled clinicl tril of customized zirconi nd titnium implnt utments for cnine nd posterior single tooth implnt reconstructions: Preliminry results t 1 yer of function. Clin Orl Implnts Res 2009; 20: Gert O, Ohlmnn B, Schmitter M, Gilde H, Ruef T, Rmmelserg P. Frcture ehvior of zirconi cermic cntilever fixed dentl prostheses in vitro. Act Odontol Scnd 2008;66: Pospiech P. Chipping systemimmnente oder verreitungsedingte Proleme?/Chipping- system-relted or process-relted prolem. Quintessenz 2010;61: Groten M. Prothetischer Lückenschluss mit viergliedrigen Zirkonoxidkermikrücken. Klinischer Fllericht üer 3 Jhre. Quintessenz 2007;58: Tinschert J, Schulze KA, Ntt G, Ltzke P, Heussen N, Spiekermnn H. Clinicl ehvior of zirconi sed fixed prtil dentures mde of DC Zirkon: 3 yer results. Int J Prosthodont 2008;21: Studrt AR, Filser F, Kocher P, Guckler LJ. Ftigue of zirconi under cyclic loding in wter nd its implictions for the design of dentl ridges. Dent Mter 2007;23: Potiket N, Chiche G, Finger IM. In vitro frcture strength of teeth restored with different ll cermic crown systems. J Prosthet Dent 2004;92: Mck MR. Verticl dimension: A dynmic concept sed on fcil form nd orophryngel function. J Prosthet Dent 1991;66: Lüthy H, Filser F, Loeffel O, Schumcher M, Guckler LJ, Hämmerle CH. Strength nd reliility of four unit ll cermic posterior ridges. Dent Mter 2005;21: Groten M, Huttig F. The performnce of zirconium dioxide crowns: A clinicl follow up. Int J Prosthodont 2010;23: How to cite this rticle: Chekhni UN, Mikeli AA, Huettig FK. All- cermic prosthetic rehilittion of worn dentition: Use of distl cntilever. Two-yer follow-up. Dent Res J 2013;10: Source of Support: Nil. Conflict of Interest: None declred. Dentl Reserch Journl / Jnury 2013 / Vol 10 / Issue 1 131