Does the Posterior Bending Osteotomy in Bilateral Sagittal Split Osteotomy Affect the Condyle Position in Asymmetric Patients?

Purpose: To measure and compare changes in postoperative condylar position following bilateral sagittal split osteotomy in patients with asymmetry treated using a posterior bending osteotomy (PBO) and conventional methods (shaving of premature contacts).Methods: Participants were randomized to either the PBO or conventional group. The inclusion criteria were the need for bilateral sagittal split osteotomy or bimaxillary asymmetric surgery (menton deviation >4 mm). The primary outcome variable was changes in the condylar position in the axial, coronal, and sagittal planes 6 months after surgery, whereas the secondary outcome variable was changes in temporomandib-ular joint symptoms. Covariates included surgery type, deformity type, age, and sex. Categorical and nu-merical variables were analyzed using Fisher exact c2 test and 2-way analysis of covariance.Results: The study sample comprised 42 patients with a mean age of 23.3 years; 57.5% were women. The alteration in the coronal condyle angle was 0.8 & DEG; ⠂ 0.86 & DEG; in the PBO and 2.72 & DEG; ⠂ 0.81 & DEG; in the conven-tional group. The differences in the condylar position in the coronal plane were not statistically significant (P = .129). The alteration in the axial condyle angle was 2.31 & DEG; ⠂ 1.74 & DEG; in the PBO group and 5.65 & DEG; ⠂ 1.65 & DEG; in the conventional group. The alteration in the sagittal plane was 0.44 & DEG; ⠂ 1.52 & DEG; in PBO and 0.47 & DEG; ⠂ 1.44 & DEG; in the conventional group. Alterations in axial (P = .194) and sagittal (P = .976) condylar positions were insignificant. In the conven-tional group, statistically significant differences were found in the axial (P = .002) and coronal (P = .002) planes, and the condyle turned inward in both planes. There were no statistically significant differences between the groups or within the groups in the sagittal plane (P > 0,5). In PBO and conventional groups, joint noise examination revealed positive results in 11 and 6 patients preoperatively and 1 and 2 patients postoperatively, respectively. A statistically significant decrease in joint noise was detected in the PBO group (P = 0,04). The maximum mouth opening without pain was 5.95 ⠂ 1.47 in the PBO group and 7.91 ⠂ 1.39 in the conventional group, respectively. The alteration was not statistically significant between the groups but was significant within the groups (P < .001).Conclusions: PBO effectively prevents premature contact between mandibular segments in facial asym-metry. & COPY; 2023 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 81:855-868, 2023