No abstract

This study was performed to address the outcomes of patients treated with onlay grafts from the iliac crest to augment the deficient jaw. The results of 173 consecutive patients who underwent bone grafting prior to implant surgery are presented. The grafts were taken from the anterior iliac crest to repair alveolar bone deficiencies that were too large to be corrected using intraoral bone grafts. Three months postoperatively, 869 implants were placed into 190 onlay grafts (167 grafts in the maxilla, 23 in the mandible). The follow-up ranged from 3 months to 23 years post implantation. All patients received a fixed prosthesis. Parameters examined included healing of the donor site and bone grafts, implant survival, peri-implant condition, and donor site morbidity. The overall survival rate for all implants was calculated to be 95% AE 2.7% according to Kaplan-Meier analysis. The implant survival rate compares favourably with those reported in studies using intraoral and extraoral bone.

Safe clinical practice in implant dentistry requires an accurate investigation of the availability of bone for implant placement and the avoidance of critical anatomical structures. Modern imaging techniques using computed tomography (CT) and cone beam computed tomography (CBCT) provide the clinician with the required information. The imaging thus obtained provides accurate representation of the height, width and length of the available bone. In addition, whenever adequate radiation dose is used, accurate information about the bone density in Hounsfield units can be obtained. Important spatial information regarding the orientation of the ridges and the relationship to the proposed prosthetic reconstruction can be obtained with the aid of radiopaque templates during the acquisition of CT scan data. Modern software also provides the facility to decide interactively upon the positioning of the implants and is able to relate this to a stereolithographic model constructed from the imaging data. A surgical guide for the accurate positioning of the implants can be constructed. The construction of screw retained prostheses is fraught with difficulties regarding the accuracy of the construction. Accurate fit of the prosthesis is difficult to obtain due to the inherent errors in impression taking, component discrepancies, investing and casting inaccuracies. CAD/CAM technology eliminates the inaccuracies involved with the investing and casting of superstructures.