CAD/CAM - international magazine of digital dentistry

I industry report _ full arch rehabilitation The different emergence profiles start from the 2mm,2.5mmor3mmposts,placedatcrestalbone level. The geometry of the abutments provides for platformswitchingevenataprostheticlevel,which isofvitalimportanceintheorganizationofthecon- necting tissue and the epithelial layer. The supraperiosteal space involved in the shift fromtheconnectingpostdiameter(2–3mm)tothe diameter of the abutment hemisphere (3–6.5 mm), allows a thicker and denser connecting tissue to form, resulting in the optimal preservation of the papilla. In the following case, all the selected abut- ments have a 3 mm post, as they must connect to the 3 mm wells of the 5.0 x 6.0 mm implants. Abut- ment post heights, inclinations and diameters are selected in the laboratory in accordance with the position of the implants relative to the anatomy of the alveolar ridge. Trinia is a CAD/CAM multidirectional fiber rein- forcedresinmaterial,whichdespiteitsleightweight is capable of withstanding occlusal forces. _Case report A 52-year-old male patient, presenting a se- verely compromised mandibular bone, was treated with the placement of four short implants. Two SHORT® implants (4.5 x 8 mm) were placed bilater- ally at the canine region and two ULTRA SHORT® implants (4 x 5mm) were bilaterally located at the first molar region (Fig. 1). The implants were placed inatwo-stagesurgeryandtheywereuncoveredaf- ter a healing period of three months (Figs. 2 & 3). Clinically, the prosthetic treatment began with an implant level transfer impression by inserting with only finger pressure a green impression post withitscorrespondingacrylicsleeveintothe3.0mm implant well, prior to recording their position by making an implant level impression with any con- ventional impression material (Fig 4). Upon the re- moval of the full arch impression, green impression posts were removed from the implant wells and inserted into an implant analog of the same color before inserting them into their corresponding acrylic sleeves within the impression. Prior to the pouring of a stone model, a resilient acrylic was applied around the impression posts to simulate a soft tissue contour in the stone model. Thestonemodelwasusedforthefabricationofawax biterimtorecordtheocclusalregistrations.Afterar- ticulationofthemodels,appropriateabutmentswith the largest practical hemispherical base were se- lected and inserted into their corresponding implant analogs within the stone model. Their prosthetic postswerethenmilledparalleltooneanother(Fig.5). The model with the milled abutments was used tofabricatealightcuredresinbaranddenturetooth setupforanintra-oralconfirmationofthearranged teeth. Once the denture set-up had been clinically approved, a facial occlusal silicone mask was ini- tially formed over the denture wax set up. Prior to formingthelingualsiliconemask,indexingoralign- ment grooves were placed in the facial occlusal mask. After fabrication of the lingual mask, grooves were cut into the stone model to prevent the sub- sequententrapmentofair,whenacrylicwaspoured into the silicone flask through anterior cut-away or aperture in the lingual mask. Prior to the removal of the wax denture tooth set up from the stone model, thefaciallingualextentofthewaxdenturetoothset up on the alveolar ridge was marked on the stone model with a pencil. After the removal of the denture teeth and wax from the resin bar, the teeth were cleaned and lin- guallyroughenedormodifiedpriortobeingfacially glued to the facial occlusal silicone mask with cyanoacrylate glue. An uneven thin application of clear resin was then applied to the cervical area of the teeth on the mask to achieve an aesthetic strat- ification of the gingival denture resin. The facial oc- clusalmaskandtheresinbarwerethenrepositioned on the model to confirm the appropriateness of theircontoursrelativetoeachotherandparticularly to the cervical gingival area of the intended teeth. If necessary, the resin bar may be modified by adding 36 I CAD/CAM 1_2013 Fig. 12 Fig. 13Fig. 11