Computer-assisted orthognathic surgery: clinical evaluation of a mandibular condyle repositioning system

Abstract

Purpose: The purpose of this study was to evaluate a new method for positioning the mandibular condyle during orthognathic surgery based on 3-dimensional optical localization of infrared emitting diodes.

Patients and methods: Eleven patients ("empirical group") underwent condylar repositioning using the empirical repositioning method (standard technique) and were considered controls. In 10 patients ("active group"), the computer-assisted system was used to replace the condyle-bearing fragment in its sagittal preoperative position. In these patients, the condylar torque was not controlled. In the third group of 10 patients ("graft group"), the computer-assisted system was used to replace the condyle in all 3 directions. Very often it was necessary in this group to fill the osteotomy gap with a bone graft. The clinical evaluation was based on 4 major criteria: the quality of the postoperative occlusion, the stability of skeletal position on successive cephalometric radiographs, the occurrence of temporomandibular dysfunction (TMD), and the preservation of mandibular motion. Clinical assessment was made at 1, 3, 6, and 12 months follow-up.

Results: Forty-five percent of the "empirical group" did not have the expected postoperative occlusion, 5 patients showed evidence of clinical relapse at 1 year, 45% had worsened TMD status, and only 63.37% of mandibular motion had been recovered at 6 months. All the patients in the "active group" had the expected occlusion and only 1 patient exhibited a mild relapse and TMD symptoms; however the average mandibular motion recovery was only 62.65% at 6 months. All the patients in the "graft group" had a good occlusion and no relapse or TMD. Their percentage of mandibular motion recovery was 77.58%.

Conclusion: The quality of sagittal repositioning is the main factor contributing to a good occlusion and bone stability. Functional results (in particular, recovery of mandibular motion) are more related to limiting condylar torque.