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ePaper created 2015-03-04, 10:43:31 | version 1.33.01
I industry report 26 I implants1_2015 Fig. 11b_Master Model Scanning. Figs. 11c & d_CAD model. Figs. 12a–c_Machined from a titanium block. Figs. 13a & b_Machined titanium framework. Figs. 13c–f_Final bridge. whichwasangled(Fig.8).Impressionofthefinalbridge wastakenwiththesameimpressiontrayasforthetem- porary bridge. Pick-up transfer copings were intercon- nected using Luxabite® resin, and the impression was made using Impregum®. The master model including the conical abutment analogs and silicone soft tissue (representingthepatient’sgingiva)wasfabricated,then validatedinthedentist’sofficeviaawaxbiteblock(into whichextrahardplastermaterialwaspoured).Then,the waxbitewastriedin(Figs.9a–d).Usingsiliconeindexes (vestibular,occlusal,palatal)fromthetemporarybridge, awax-upwasfabricatedinthelaboratory(Fig.10).The wax-upmustmeettheaestheticdemandofthepatient andshouldbetheexactreplicaofthetemporarybridge (both anatomically and aesthetically). The validated master model and wax-up were forwarded to the Simeda® machining centre where the master model was scanned. Then, a CAD model was designed (Figs. 11a–d).APDF3Dfileisusedtovalidatethedesign,after which the manufacturing process can be initiated. All pieces are machined from titanium blocks using high- precision5-axismillingmachines(Figs.12a–c). Titaniumisalightweightmaterial,andmoreimpor- tantly, it is highly biocompatible and has superior me- chanical properties. It is four times lighter than com- monlyusedsemi-preciousalloys.Actually,itisthelight- est metal used in dentistry. Furthermore, titanium is a self-passivating metal: it readily reacts with oxygen in air to form a tough layer of oxide which protects from corrosion.Titaniumisknowntoresistextremelywellto corrosionandchemicalattacks.Italsohasanadditional key advantage for a dental implant: it is bactericidal. Material density is a crucial factor in implantology. We believe that the weight of a maxillary implant-sup- portedprosthesisisthemostimportantfactorininflu- encingtheoutcomeoftherestoration. Afewdayslater,wereceivedtheframeworkforatry- in. It had a perfect passive fit and was returned to the laboratoryforveneering.Firstlabstepsaremetalprepa- ration: sandblasting, titanium etching and application of opaquer porcelain to conceal the metal core. Then, thebisquebakewastriedintoallowthepatienttoval- idate the aesthetics of the restoration. This step is nec- essary to assess static and dynamic occlusion and per- formminoradjustments(Figs.13a&g).Thebisquebake wasthenreturnedtothelaboratoryforfine-tuningand glazing. _CAD/CAM benefits Although conventional casting techniques have evolved, they are still fraught with inaccuracies due to the nature itself of the materials and to their handling. Thisincludes:riskoferrorsduringinvestmentprocess- ing, risk of metal deformation, poor metal homogene- ity etc. The CAD (computer-aided design) and CAM (computer-aided manufacturing) technologies used Fig. 11b Fig. 11c Fig. 11d Fig. 12a Fig. 13a Fig. 13b Fig. 13c Fig. 13d Fig. 12b Fig. 12c