Computer-Assisted Surgery in the Edentulous Jaw Based on 3 Fixed Intraoral Reference Points

Purpose In computer-assisted implantation surgery, the transfer of prosthodontic-guided planning to the operative site is usually based on a registration template. The precise repositioning of the registration template is crucial for high accuracy and is compromised in edentulous jaws. The purpose was to determine the in vitro registration and targeting accuracy for surgical navigation in the edentulous jaw based on 3 fixed intraoral reference points. Materials and Methods Edentulous maxilla and mandible cadaver specimens were provided with 3 fixed reference-point screws. A resin template with matrices for the fixed reference-point screws was produced and connected to a Vogele-Bale-Hohner registration mouthpiece and external registration frame with a snap-lock system. Surgical implants were planned on computed tomographic data and the corresponding dental stone casts were drilled under guidance of an optical navigation system. For evaluation of the registration accuracy, fiducial registration error was recorded and application accuracy was evaluated by fusion of postsurgical computed tomographic scans of the drilled dental stone casts with the presurgical planning computed tomogram. Results In 9 maxillas and 5 mandibles, 14 registrations and 104 stone cast drillings were performed. The mean fiducial registration error was 0.49 ± 0.14 mm (0.37 to 0.9 mm). The mean total error at the tip of the borehole was 0.88 ± 0.65 mm (0.0 to 4.24 mm). The mean lateral errors were 0.51 ± 0.49 mm (0.0 to 2.80 mm) at the base and 0.46 ± 0.34 mm (0.0 to 1.5 mm) at the tip of the borehole, respectively. The mean angular error was 0.83 ± 0.60° (0.0 to 2.5°). Conclusion Three fixed intraoral reference points successfully support a registration mouthpiece and provide in vitro registration and targeting accuracy that is comparable to tooth-supported registration templates or bone marker registration.