Accuracy of a Navigation System for Computer-Aided Oral Implantology

Placement of endosteal implants is a widespread therapy for re-establishing full functionality in edentulous patients. As a first application of VISIT, a modular software system for research into computer-aided surgery developed at our hospital, we have implemented a navigation system for computer-aided implant dentistry (CAID). Besides improved accuracy, benefits of CAID include fast translation of preoperative imaging to the operating theatre and the possibility to insert the implants without having to prepare large mucosa flaps. In this cadaver study, we have measured the overall accuracy of VISIT for inserting four intraforaminal implants in the edentulous mandible. Five cadaver mandibles were embedded into plaster. After high-resolution CT scanning, the mandibles were registered, and the implant channels were drilled by the surgeon. Training implants were inserted into the implant channels, and the plaster was removed. Again, the mandibles underwent CT scanning, and the pre- and postoperative scans were registered relative to each other. A gross registration between pre- and postoperative scans was achieved using surface- or mutual information matching since in some cases the fiducial markers were lost. After transformation to a common coordinate system, the accuracy was assessed by measuring the distance of the implant’s center to the cortex of the jawbone. Average accuracy of the navigation system was found to be 0.9 ± 0.7 mm, range {0.0 ...3.5} mm. We conclude that these results show that CAID is an interesting novel application of computer-aided surgery superior to conventional methods in oral surgery.