CHANGES IN BITE FORCE AND OCCLUSAL CONTACTS IN PATIENTS TREATED FOR MANDIBULAR PROGNATHISM BY ORTHOGNATHIC SURGERY

Purpose: The purpose of this study was to evaluate changes in bite for ce and occlusal contacts before and after orthognathic surgery in pati ents with mandibular prognathism and to compare the findings with thos e in controls with normal occlusion. Patients and Methods: Bite force and occlusal contacts were analyzed in 23 (7 male and 16 female) patie nts with mandibular prognathism before and after sagittal split ramus osteotomy, and in 20 (10 male and 10 female) controls with normal occl usion. The bite force and occlusal contacts were simultaneously measur ed by a computerized occlusal analysis system, the T-Scan system, imme diately before surgery, and at 6 weeks, 3 months, 6 months, and 1 year postoperatively. Results: Both the bite force and occlusal contacts i n the patients were significantly less than those in the controls befo re surgery. Although both the bite force and occlusal contacts in the patients were improved by the orthognathic surgery, neither approached the level in the controls within 1 year. Bite force was correlated wi th the number of occlusal contacts in both patient and control groups. Conclusion: The postoperative masticatory function does not reach con trol levels even 1 year after the orthognathic surgery for mandibular prognathism. Therefore, further adjustment of the occlusion should be considered before the end of treatment.