CAD/CAM international magazine of digital dentistry

18 I I case report _ CAD crown design planning of the treatment steps and the pre- dictability of the post-operative result. The surgical procedure was determined on the basis of the digital volume tomogram (DVT). The central issue was the optimal method of recon- structing the resorbed bone. Sincethehorizontalbonevolumewasadequate, spreading the alveolar ridge by means of bone splitting in combination with implant placement andguidedboneregenerationwasthetreatmentof choice. The anatomy of the patient’s alveolar ridge and his bone quality confirmed the decision to use the XiVE implant, as its unique surface promotes the stable attachment of osteogenic cells and its apically increasing thread depth contributes to a high degree of primary stability. In the DVT trans- verse view, a XiVE implant with a diameter of 3.8 mm and a length of 13 mm was virtually placed using the software in the optimal implant position. It was established that the buccal lamella would have fallen short of the layer thickness of 1 to 1.5 mm necessary for the long-term retention of the implant (Fig. 2). Since this is indispensable for uneventful healing and an aesthetic result, the bone splitting was to be performed to a depth of 7 to 10 mm. The 3-D image demonstrated that the bone volume was adequate for this procedure. In addition to the bone splitting, a final lateral onlay graft had to be performed. The axial view of the 3-D image is well suited to estimating the position of the nasopalatine nerve (Fig. 3). The position of the nerve is a limit- ing factor for the implant position in the palatal direction. The risk of a fracture of the buccal lamella or of damage to the nerve, however, is small when the correct procedure is used. Surgicalprocedure The mucoperiosteal flap was prepared and raised for the purposes of a full thickness flap. The periosteum was carefully detached from the bone (Fig. 4). Following the completion of the implant placement, the sutures should be located approximately over the split bone with the in- serted implant. The alveolar crest at the planned implant site was initially marked using a round drill and then enlarged with a pilot drill. In the next step, two small vestibular incisions and a horizontal incision to a depth of 10 mm and at an angle of 90 degrees were done using the Piezotome(Acteon;Fig.5).Thetworelativelydeep (5 to 7 mm) vertical incisions prevent a fracture of the buccal lamella, improve its mobility and protect the marginal periodontium of the adja- cent teeth. The alveolar bone was then gradually expanded horizontally using the appropriate in- struments (Fig. 6). In the process, the bone was also condensed horizontally at the same time by compression to improve the primary stability of the implant. Using a twist drill, the bone for the implant site was prepared gradually (Fig. 7). The bone chips were removed simultaneously viathegroovesinthetwistdrilltowheretheycould be collected extra-orally. The implant site was pre- paredatlowspeedinordertoavoidoverheatingthe tissue. The vestibular lamella was stabilised by the apically pedicled flap on the periosteum and fixed. After the final drilling, the actual preparation of the implant site was complete. The bone-specific crestal preparation of the cavity was then carried out using the crestal twist drill to adapt the prepa- ration to the clinical situation (Fig. 8). In the next step, a XiVE S plus implant with a diameter of 3.8 mm and a length of 13 mm was Fig. 8_Finally, the crestal bone preparation was carried out. Fig. 9_The XiVE S plus implant was mechanically inserted at a slow rotational speed. Fig. 10_After filling the defect with autogenous bone chips, a stable-volume alloplastic bone-grafting material was placed over the bone chips as a second layer, and a resorbable collagen membrane was fixed to the bone with two FRIOS membrane tacks. Fig. 11_A double-layered wound closure was performed using resorbable suture material. Fig. 12_The radiological control demonstrates that the XiVE implant in region #21 was positioned nearer to tooth #22 than to tooth #11 owing to the location of the nasopalatine nerve. CAD/CAM 4_2012 Fig. 12 Fig. 11Fig. 10 Fig. 9Fig. 8