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CD0412

CE article _ mastering occlusal function I to a physical impression to be used for a provisional restoration. A pre-operative scan must accurately capturethethree-dimensionalshapeofthesoon-to- be-preparedtooth,alongwithadjacentteeth.Cross- ingthemidlineisnotusuallynecessaryunlesswork- ingonanteriorteeth.Theadjacentteeth’sanatomies areusedasstitchingabutmentswithinthesoftware. Thismeansthatthepre-operativemodelwillbecom- pared with the prepared tooth digital model and the twomodelsaresplicedthree-dimensionally(Fig.19). If the stitching abutments within the preoperative model and the prepared model were not the same or lacking data, the models would not be able to be spliced.Thescanneddataissavedwithintheprogram and used later during the restoration design phase. The design phase of Biogeneric Copy is simply drawing a zone for which the computer will dupli- cate (Fig. 20). Then the design is manipulated as the clinician sees fit. Decisions can be made for resto- ration shape while comparing the proposed design to the pre-operative scan taken before tooth prepa- ration.Thepre-operativesurfaceisessentiallyashell to construct the digital design of the restoration. The Biogeneric calculation determines the rest of the areas outside of the copied zones. The design (in white)iscomparedtothepre-operativescan(ingray) (Fig. 21). A speckled gray/white appearance shows that the two surfaces are in complete congruence. Foranyareawherethereiswhite,itisprotrudingout- side the boundary of the original tooth surface and maycauseaninterferencewithocclusion.Withgood clinical judgment, this is usually not a problem. _Case 2 A 38-year-old male went through extensive jaw surgery and orthodontics to alleviate a severe class 2malocclusion. Hisverticaldimensionofocclusion was opened up about 2 mm in the posterior and Fig. 20_A circle is placed to designate areas for the computer to copy the preoperative surface. Fig. 21_The preoperative shell (gray) is compared to the digitally designed restoration (white). Fig. 22_New vertical dimension of occlusion established intraorally with composite and ready for reproduction in ceramic. Fig. 23_The finalized ceramic crowns (IPS e.max CAD) at 18, 19 and 20 reflect the occlusion and shape established in composite. I 11cosmeticdentistry 4_2012 Fig. 20 Fig. 21 Fig. 22 Fig. 23