An alternative method to match planned and achieved positions of implants, after virtual planning using cone-beam CT data and surgical guide templates - A method reducing patient radiation exposure (part I)

Objectives: The present study describes a new method of evaluating the precision of surgically placed dental implants compared after virtual planning of implant positions using cone-beam computed tomography (CT) data and surgical guide templates. This method reduces radiation exposure for patients participating in scientific studies. Materials and methods: Twenty-three implants in 10 patients with a unilateral free-end gap in the mandible (Kennedy Class II) were evaluated. After three-dimensional planning of implant position, the implant bed was prepared with a surgical guide template and transmucosal drilling. Preoperative cone-beam CT images were matched with postoperative images of the master cast with implant replicas. Deviations between planned and achieved positions were measured in position and axis. Results: On average, the match between planned and placed implant axis was within 4.2 degrees (range, 0.0-10.0). The mean difference in distance at the implant shoulder was 0.9 mm (range 0.0-4.5). The mean difference in distance at the implant apex was 0.6 mm (range, 0.0-2.7) in the lateral/medial direction and 0.9 mm (range, 0.0-3.4) in the anterior/posterior direction. Conclusions: This alternative matching method provides reliable postoperative evaluation of differences in position and axis of planned and placed implants while reducing patient radiation exposure. (C) 2009 European Association for Cranio-Maxillo-Facial Surgery