Computerized Navigation for Surgery of the Lower Jaw: Comparison of 2 Navigation Systems

Purpose: To evaluate the accuracy and applicability of 2 computerized navigation systems for surgery of the lower jaw. Patients and Methods: Two patients diagnosed with a mucoepidermoid carcinoma of the lower jaw were prepared for tumor resection applying 2 different computerized navigation systems: the Image-Guided Implantology (IGI) system (DenX Advanced Dental Systems, Moshav Ora, Israel), which is specialized for dental implant surgery and the LandmarX system (Medtronic Xomed, Inc, Jacksonville, FL), which is designed for ear, nose, and throat surgery. Intraoperative accuracy of navigation of each of the systems was evaluated from the precision of targeting of distinctive anatomical landmarks in the mandible, including a preoperatively placed titanium screw. Results: The navigational error of the IGI system was less than 0.5 mm, while that of the LandmarX system was between 3 mm and 4 mm. Tumor resection was performed with the guidance of the IGI system, and resulted in complete resection with tumor-free margins. Conclusions: The mobile nature of the lower jaw complicates its synchronization during surgery with the preacquired imaging data. The accuracy of navigation based on tracking of the patient's head is compromised by asynchronous movements of the mandible during surgery. Direct tracking of the lower jaw, via a teeth-mounted sensor frame, is superior to its indirect tracking. The teeth also provide a more secure basis for the fiducial markers than soft tissue attachment. We conclude that a computerized navigation system using a teeth-mounted sensor frame and teeth-supported fiducial markers enables more accurate navigation for surgery of the lower jaw.