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CAD0111

26 I I industry report _ CAD/CAM bar restoration FriadentMPabutment(Fig.6)andsplintedtogether using as little autopolymerisate as possible (Fig. 7). Thefinalabutmentsalwaysremaininthemouthfrom this point in time onwards. This has the benefit that peri-implant bone resorption is limited and the soft tissues can heal undisturbed. The impression was made with two-phase silicon (Aquasil Ultra, DENTSPLYDeTrey;Fig.8).Themastercastwasmade of class IV dental stone. Making a gingival mask is part of the standard procedure (Fig. 9). Fabricating two precision impressions allows maximum accu- racytobeachievedwithwide-spansuperstructures. Ifanyinaccuraciesareperceivedduringtheimpres- sion and model manufacturing process, the corre- sponding step has to be repeated in each case. _Manufacture and try-in of the bar In order to fabricate the XiVE CAD/CAM bar, only the result of the wax try-in was still necessary. This wasperformedinaseparatesessionusingaplastic- basedtemplate(Figs.10&11).Thewaxtry-inisfixed onto two implants to facilitate better and definite positioning (Fig. 12). Together with the master cast, theset-upwasthensenttotheDENTSPLYCAD/CAM centre, where both were scanned in with a cus- tomised system. The data records resulting from the scan served as a basis for constructing the bar. At the latest, the construction proposal leaves the DENTSPLY CAD/CAM centre one day after receipt of the model by e-mail. The construction is checked with the viewer software provided by DENTSPLY Friadent at no cost (Fig. 13). The jaws, bar and set- up can easily be shown, hidden and viewed from all angleswiththesoftwareprovidingoptimalcontrol. At this point, the DENTSPLY CAD/CAM centre still accepts corrections. After the design has been approved, the data record is e-mailed back to the DENTSPLY CAD/CAM centre. The CAD/CAM structure is delivered within seven days after the approval has arrived. In our ex- perience, any conceivable bar solution in any size andtypecanberealisedwiththeDENTSPLYFriadent range, for example Dolder bars, round bars or even bars with different retaining elements. At delivery, the bar already exhibited a quality of finish equal to a highly polished state (Fig. 14). We first checked the accurate fit on the master cast before we sent the bar for a try-in at the dental practice. In order to detect any gap formations on the opposite side, the bar was first screwed in (Sheffield test) on one side. The fit also proved to be very accurate, even intra-orally (Fig. 15). X-ray con- trol of the completely screw-retained bar provided additional security (Fig. 16). _Completion After the bar was slightly revised and given a finalpolish,theGalvanointermediatelayercouldbe made(Fig.17).Aftermakingthemodelcastingscaf- fold for the denture, the bolts were fitted (Fig. 18). Before completing the bar denture, a second wax try-in was carried out for functional fine adjust- ment.Inordertoensureoptimalstability,wealways makethebasalportionsofdenturesfromcoldpoly- merisate. During the finishing process, the soft tissues were replaced with individually fashioned plastic. As patients recognise the clear aesthetic difference to their previous dentures, individual Fig. 11_The basis of the wax-up with the sunken impression copings. Fig. 12_Screw-retaining the wax-up with the two distal implants ensures the correct position when fitting. Fig. 13_The construction proposal supplied by DENTSPLY CAD/CAM centre. Fig. 14_The bar milled according to the dental laboratory’s specifications fits perfectly on the laboratory analogue. The bolt eyes for the planned MK1 locking bolts are clearly recognisable in the distal extensions. Fig. 15_The bar fits accurately onto the implants and has tissue-friendly adaptation to the alveolar ridge. Fig. 16_The X-ray control after screwing the bar in. CAD/CAM 1_2011 Fig. 13 Fig. 14 Fig. 11 Fig. 12 Fig. 15 Fig. 16