Changes in the duration of the chewing cycle in patients with skeletal class III with and without asymmetry before and after orthognathic surgery.

PURPOSE: The purpose of this study was to examine the changes in the chewing rhythm before and after mandibular ramus osteotomy in patients with prognathism with and without asymmetry. PATIENTS AND METHODS: We divided 12 men and 22 women with mandibular prognathism into groups on the basis of symmetry and osteotomy procedure. The duration of the chewing cycle was recorded preoperatively and postoperatively. The duration of the chewing cycle and coefficient of variation were compared between groups, and the differences were analyzed statistically. RESULTS: No significant differences in each of 3 phases of the chewing cycle and total duration were found between groups on the basis of symmetry or osteotomy procedure. However, there were significant differences between the preoperative and postoperative coefficients of variation for the undeviated side in the asymmetry group (P = .0037) and in the group undergoing sagittal split ramus osteotomy (P = .0166). CONCLUSION: This study suggests that surgical orthodontic treatment does not significantly change the duration of the chewing cycle.