Digital cross-mounting: A new opportunity in prosthetic dentistry

Transcription

1 PROSTHODONTICS Digitl cross-mounting: A new opportunity in prosthetic dentistry Pietro Venezi Pietro Venezi, DDS 1 /Ferruccio Torsello, DDS, PhD 2 /Slvtore D Amto, MD, DDS 3 /Rffele Cvlcnti, DDS, PhD 1 The prosthodontic mngement of complex rehilittions requires severl stges of tretment including one or more provisionl restortions. The design nd djustments of the provisionl re mde to chieve n optiml functionl nd esthetic outcome for the ptient. However, the djustments needed re oth time nd cost consuming. Therefore, once stisfctory provisionl is mde, the informtion should not e lost during the following stges of tretment. The purpose of this clinicl cse is to illustrte digitl cross-mounting, procedure used to precisely trnsfer informtion from the provisionl to the finl fixed rehilittion in digitl workflow. (doi: /j.qi.38863) Key words: cross-mounting, digitl workflow, full-rch rehilittion, introrl scnner, monolithic zirconi The rehilittion of one or two completely edentulous rches is complex nd requires n interdisciplinry tem pproch comining the proficiency of the prosthodontist, the periodontist, the orl surgeon, nd the dentl technicin. The concept of prostheticlly guided rehilittion is universlly recognized: the position of the prosthesis should e the guide for the periodontl nd implnt surgery. 1 When plnning the rehilittion for full-rch restortion, severl prmeters should e tken into considertion in order to chieve functionl prosthesis with n estheticlly plesnt result. These include the 1 Privte Prctice, Bri, Itly. 2 Reserch Fellow, Deprtment of Periodontics nd Prosthodontics, Estmn Dentl Hospitl, Rome, Itly. 3 Aggregte Professor, Multidisciplinry Deprtment of Medicine nd Dentistry, Unit of Mxillo-Fcil Surgery, University of Cmpni Luigi Vnvitelli, Nples, Itly. Correspondence: Dr Pietro Venezi, Studio di Odontoitri Specilistic Cvlcnti & Venezi, Vi G. Posc, 15 Bri (BA), 70124, Itly. Emil: pierovenezi@gmil.com crniomndiulr reltionship with the determintion of centric reltion position with n dequte verticl dimension, the orienttion of the occlusl plne three dimensionlly, the occlusl reltionship, the periorl tissue support, the tooth disply, nd the phonetics. 2-9 In the dily routine, the clinicin records the forementioned functionl nd esthetic prmeters. With the dignostic informtion, the dentl technicin frictes the wx-up nd the provisionl restortion. The csts should e mounted on the rticultor in centric reltion t the correct verticl dimension with the id of fceow registrtion. Once the provisionl restortion is produced, it is used not only to provide the ptient with interim prosthesis, ut lso to test the function nd esthetic chnges, s this restortion could e modified for improvement severl times in reltively esy mnner. After proper period of time with functionl nd esthetic provisionl restortion, the definitive prosthesis cn e fricted. The finl prosthesis should e identicl to the provisionl, ut with more durle doi: /j.qi

2 Venezi et l c Figs 1 to 1c Initil introrl photogrphs. Fig 2 Initil rdiogrphic sttus. mteril. The trnsition from the temporry to the definitive prosthesis is complex, s it is difficult to reproduce exctly the detils of the provisionl restortion. Some techniques hve een proposed to trnsfer ll the prosthetic informtion (verticl dimension, centric reltion, frontl nd lterl guidnce, esthetics) in cses treted with fixed provisionl prosthesis supported either y teeth or y implnts. 10,11 Another technique hs een proposed for cses in which the provisionl nd dignostic phse is performed with removle denture. 12 The im of this rticle, illustrted through clinicl cse, is to integrte fully digitl workflow to ccurtely trnsfer dignostic informtion from the provisionl stge to the definitive fixed prosthesis for fullrch implnt-supported rehilittion. CASE REPORT The ptient, 51-yer-old womn, presented with severe ttchment loss, multiple sites with cute infection, nd moility in the mxillry rch (Figs 1 nd 2). The periodontl chrt ws completed nd set of peripicl rdiogrphs ws performed in order to determine the prognosis of the teeth in the mxill nd in the mndile. Preliminry impressions were tken with irreversile hydrocolloid (Blueprint Xcreme, Dentsply DeTrey). The dignostic csts were rticulted on semi-djustle rticultor with the id of fceow registrtion nd centric reltion wx index. Fcil nd dentolil nlyses were crried out s well s phonetic tests. After this creful exmintion it ws decided tht ll the remining teeth in the mxillry rch should e extrcted. Severl tretment options were reviewed with the ptient, nd full-rch implnt-supported fixed restortion ws selected s the most pproprite for the ptient s needs nd expecttions. With regrds to the timing of extrctions nd implnts, immedite plcement ws excluded ecuse of the presence of cute infections. As the ptient desired voidnce of ny removle pplince in the provisionl phse, stged pproch ws followed, temporrily mintining few teeth in order to support provisionl fixed restortion doi: /j.qi.38863

3 Venezi et l Figs 3 to 3c Anterior photogrphs tken immeditely fter tooth extrctions nd socket preservtion procedures, t the moment of delivery of the first provisionl restortion nd fter the heling period. c A prescription with precise indictions regrding the verticl dimension, the position of the new incisl edge, nd the desired occlusl scheme ws sent to the dentl lortory technicin, who produced wx-up of the prosthetic project. It ws decided to mintin three teeth in strtegic positions (the mxillry right nd left cnines nd left second premolr) s utments for fixed provisionl restortion of polymethyl methcrylte (PMMA) with metl reinforcement tht ws mnufctured y the technicin with n nlogic workflow efore tooth extrctions. The mxillry right nd left cnines nd left second premolr were endodonticlly treted. In one single clinicl session, ll teeth with the exception of the mxillry right nd left cnines nd left second premolr were extrcted nd socket preservtion procedures were performed with mix of inorgnic ovine one nd porcine collgen (Bio-Oss Collgen, Geistlich Phrm). In the sme session, the nturl utments in the positions of the mxillry right nd left cnines nd left second premolr were prepred nd the provisionl restortion ws relined, refined, nd cemented. The ptient ws checked 10 dys lter for suture removl nd for control of her orl sitution (Fig 3). Therefter, the heling of soft nd hrd tissues ws controlled every 6 weeks. Seven months fter tooth extrctions, six implnts were plced with the id of surgicl templte: two Bone Level Tpered implnts (Strumnn) in the mxillry lterl incisor positions (dimeter 3.3 mm) nd four Soft Tissue Level implnts (Strumnn) in the mxillry first premolr positions (dimeter 3.3 mm) nd in the mxillry first molr positions (dimeter 4.1 mm). All the implnts presented with sndlsted, cid-etched, chemiclly ctivted surfce (SLActive, Strumnn). The use of metl-reinforced provisionl on nturl utments llowed undistured heling of the implnts nd provided the ptient with fixed restortion for the whole durtion of the tretment. After n osseointegrtion period of 8 weeks, the implnts were visully inspected nd hnd-checked nd were considered redy to support the loding From this moment totlly digitl workflow ws used. doi: /j.qi

4 Venezi et l Figs 4 nd 4 Occlusl photogrphs of nturl utments nd heled implnts with scn odies in situ nd opcizing powder used to ccelerte the scn. Figs 5 nd 5 Digitl impressions of the mxillry nd mndiulr rches efore intermxillry registrtion. The temporry prosthesis nd the heling utment were removed, the Scn Bodies provided y the mnufcturer for introrl scn (Scn Body, Strumnn) were secured to the implnts, nd the digitl implnt impression of the mxillry rch ws tken (Fig 4). This cquisition provided the informtion regrding the position nd the morphology of implnts nd remining teeth, s well s periodontl nd peri-implnt tissues. The digitl impression ws widely extended towrds the plte to record the ruge pltine nd the incisl ppill nd towrds the vestiule to include not only the teeth ut lso the surrounding structures (Fig 5). 17 The scnner used for this clinicl cse (True Definition Scn, 3M Espe) opertes with contrst ptterning powder to increse the speed of the impression, to fcilitte the dt cquisition, nd to improve its ccurcy. The digitl impression of the mndiulr rch ws then cquired in second scn (Fig 5). The scn odies in the mxillry rch were removed, the provisionl prosthesis repositioned, nd third cquisition ws performed on the vestiulr side with the provisionl prosthesis in situ with mxillry nd mndiulr rches in contct. This cquisition llowed for the ite registrtion etween the mxillry nd mndiulr scns: in the ite registrtion function, the softwre ws designed to tke into considertion only the lndmrks needed for this purpose. The cre tken in the previous scns to extend the cquisition to the soft tissues llowed recording of enough points in common with the ite registrtions. Consequently the mxillry nd mndiulr rches were digitlly mounted with the correct intermxillry reltions (Fig 6). This procedure could e nmed digitl cross-mounting s it replictes the process of nlog cross-mounting (Fig 6). A fourth impression (uxiliry scn) of the mxillry rch with the provisionl prosthesis in situ ws tken. 4 doi: /j.qi.38863

5 Venezi et l Once gin, cre ws tken to extend the cquisition to the surrounding structures (ruge pltine, periodontl structures) tht provide the references to superimpose the different digitl impressions. The im of the uxiliry scn ws to provide the dentl lortory technicin with informtion regrding the functionlized provisionl prosthesis, such s the incisl edge position, the occlusl plne, the incisl nd cnine guidnce, the occlusl contcts, nd the width nd length of the teeth (Fig 7). Once the intermxillry reltion ws estlished in the plnning softwre, the utments were chosen from the softwre lirry (Vriose utments, Strumnn). Before proceeding, the ccurcy of the scnned implnt position ws tested: resin jig ws designed with the softwre, milled, luted on the utments, nd tried introrlly (Fig 8). Since good fit nd precision were found oth cliniclly nd rdiogrphiclly, the digitl impression ws ccurte nd the process of fricting new, implnt-supported provisionl ws strted. The remining nturl utments (the mxillry right nd left cnines nd left second premolr) were virtully extrcted nd the provisionl restortion ws designed on the sis of the informtion regrding the shpes nd volumes of the tooth-supported provisionl tht ws previously scnned (Figs 9 nd 10). Ovte pontics were designed t the plnned extrction sites to guide soft tissue heling nd condi Figs 6 nd 6 Bite registrtion using the provisionl restortion. This registrtion llows mounting of the mxillry nd mndiulr digitl impressions in the correct reltion. c Figs 7 to 7c Digitl impression of the mxillry rch with the provisionl prosthesis. doi: /j.qi

6 Venezi et l Figs 8 nd 8 Design nd try-in of the verifying jig. Figs 9 nd 9 The mxillry nd mndiulr digitl impressions in the correct intermxillry reltions fter the digitl cross-mounting procedure in the dentl technicin softwre. Nturl utments hve een virtully extrcted nd Vriose utments plced on implnts. Fig 10 Superimposition of the digitl impressions of the implnts nd of the provisionl restortion. tioning. 18,19 Cnine nd incisl guidnce were checked with the digitl rticultor function of the softwre. The project ws then relized y milling PMMA lock, the new provisionl ws luted to the Vriose utments nd sent to the dentl clinic. The three remining nturl utments were removed nd socket preservtion procedures were performed to mintin one volume t the pontic sites. A few minutes fter the surgicl session, the screw-retined provisionl ws delivered to the ptient: it demonstrted excellent fit nd precision nd only minor occlusl djustments were needed (Fig 11). The implnt-supported provisionl prosthesis ws kept for 7 months for complete heling t the extrction sites nd complete soft tissue conditioning (Fig 11). This period ws lso useful to test once gin the prosthetic project. Since no dmge (chipping or frcture) to the resin ws found nd no screw loosening recorded, the project ws considered pproprite nd it ws decided to replicte it in more durle mteril. A new digitl impression of the implnt-supported provisionl ws tken to record the soft tissues round the implnts nd the ovte pontic res nd to visulize eventul occlusl wer. This impression ws mtched with the virtul mster model nd the implnt nlogs (Fig 12). 6 doi: /j.qi.38863

7 Venezi et l c Figs 11 to 11c Occlusl views of the mxillry rch () immeditely fter tooth extrction, () fter the delivery of the monolithic PMMA implnt supported provisionl restortion (sme dy), nd (c) fter 7 months of heling. Fig 12 Digitl project of the finl restortion. A definitive screw-retined rehilittion in monolithic zirconi with porcelin veneering limited to the lil surfce ws mnufctured. 20 A virtul cut-ck of the vestiulr surfce from the digitl impression of the provisionl ws performed to llow porcelin strtifiction. Occlusl nd pltl surfces were left unmodified, since no veneering ws to e performed. The zirconi frmework ws milled with n occlusl surfce identicl to the provisionl fter 7 months of use nd tried-in to verify the fit nd occlusl contcts ccording to mutully protected occlusl scheme (Fig 13). Mxillry nd mndiulr resin csts were produced with three-dimensionl (3D) printing mchine sed on STL-files (Dreve Dentmid) to position the zirconi frmework nd to fcilitte the veneering of feldspthic porcelin. The occlusl nd pltl res were infiltrted with colors optimized for zirconi, nd the vestiulr spect ws veneered with porcelin (E-mx Cerm, Ivoclr Vivdent). The prosthesis ws cemented to the titnium utments with resin cement (Pnvi F, Kurry) nd delivered to the ptient (Fig 14). DISCUSSION AND CONCLUSION Complex rehilittions require considerle mount of time nd effort in tretment plnning, nd severl stges of tretment with one of more provisionl restortions. The possiility to keep the informtion during the trnsition from the provisionl to the finl restortions hs een nlyzed in previous ppers. The cross-mounting technique, s descried y Clesini et l 11 in 1996, llows perfect interchnge of the csts, replicting the provisionl restortion with the mstercsts of oth rches. 11 All the comintions of the four csts (two of doi: /j.qi

8 Venezi et l Fig 13 Zirconi frmework try in. The frmework is otined y digitl duplicte of the provisionl nd virtul cut-ck of the vestiulr surfces. Fig 14 Introrl view of the finl rehilittion in plce. the provisionl rches nd two mstercsts) could e mounted on the sme rticultor t the sme verticl dimension nd with the sme 3D sptil reltionships. In the sme rticultor, with the id of silicon indexes recorded on the provisionl csts, it is lso possile to comine the informtion regrding the finl restortions with the mstercsts. New technology, such s digitl impressions nd computer-ided design/computer-ssisted mnufcture (CAD/CAM), hs improved the production of prosthetic devices in prosthodontics. The possiility to hve precise reproductions of dentl rches is not sufficient in cses when intermxillry reltion is difficult to record. This is the cse when one or oth rches re edentulous. The uthors developed protocol to record the intermxillry reltion in digitl mnner to hve fully digitl workflow. The protocol ws inspired y the cross-mounting procedure tht ws used for severl yers y the uthors, ut modified to e used with digitl technology, which simplified the process for the clinicin nd the dentl technicin. The softwre cquires the impressions of the edentulous rch nd the opposing rch, nd records the correct reltion through the scn of the uccl spect in occlusion with the provisionl restortion in situ. After the superimposition, the ite registrtion with the provisionl is removed in the softwre nd the result is the visuliztion of the two rches in the correct intermxillry reltion. Furthermore, the softwre overlps the provisionl prosthesis to verify the functionl nd esthetic informtion, such s incisl edge position, incisl guidnce, tooth volumes, nd posterior occlusl contcts. This results in n esier design of the finl rehilittion tht is identicl to the provisionl. A consequence of this pproch is to emphsize the importnce of the provisionl phse, which is, in the uthors opinion, prt of the dignostic phse. For this reson gret cre is tken to provide the ptient with temporry restortion tht should e estheticlly nd functionlly dequte. Severl djustments should e mde nd kept in the mouth nd tested for resonle period of time. The design of the provisionl nd djustments mde to dpt it to ptient s function nd esthetics re time consuming; thus, once n dequte nd plesing result is chieved, the informtion gined should not e lost during the rest of the tretment: the finl rehilittion should e identicl to the temporry prosthesis in more durle mteril. ACKNOWLEDGMENTS The uthors thnk Dr Ctherine DeFuri for her lnguge review. The uthors thnk Psqule Lcsell nd Frncesco Grieco for their help in the lortory procedures. 8 doi: /j.qi.38863

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