[Ct-assisted navigation for insertion of dental implants in maxilla models]

The use of CT-based intraoperative navigation has greatly improved controlled surgery in many specialties. In this study the precision of the SMN system (Zeiss, Oberkochen, Germany) for navigated drilling and following implantation in the maxilla is evaluated. This study should prove the suitability of navigation systems for computer-assisted implantation in the maxilla to avoid perforation to the maxillary sinus. Therefore 60 target drills were carried out on 10 standardized polyurethane milling models after CT-scanning. The models were produced with cranial open maxillary sinuses. The CT-scans were performed with a slice distance of 1 mm. Then the CT-data were transferred to the workstation of the SMN system (Zeiss, Oberkochen, Germany) and a referenciation of the fiducials for superposition of the native and CT model were done. Referenciation of the model was performed with the aid of a drilling tool. This drilling tool was used for later navigation-assisted drilling into the upper jaw. The target of drilling was the maxillary sinus floor. The aim was to come as near as possible without perforation. The distance of the bottom of the drilling holes to the maxillary sinus floor were measured after section of the model. An average drilling depth of 6.97 mm (s=0.4) and a mean distance to sinus floor of 0.11 mm (s=0.2) was found. In 13 cases the lower board of sinus was perforated.In conclusion a high precision of CT-based navigation for controlled preimplantological drilling was seen.