Mandibular Stability After Sagittal Split Ramus Osteotomy With Hybrid Technique in Asymmetric Patients

The hybrid technique after bilateral sagittal split ramus osteotomy is an internal fixation method using monocortical mini-plates and additional bicortical positional screws. In this study, we analyzed the postoperative stability of 23 patients with mandibular asymmetry who underwent bilateral sagittal split ramus osteotomy and hybrid fixation with or without LeFort I osteotomy. Anatomical landmarks of the deviated and non-deviated sides of the jaw were established to measure the angle and distance to the reference plane in three-dimensional cone beam computed tomography images. We analyzed the positional changes and correlations of the reference points at preoperative (T1), postoperative 2 weeks (T2), and postoperative 1 year (T3). There were significant differences in preoperative position of the upper and lower molar cervix alveolar crest to the reference plane (U6-X and L6-X) and the condylion angles between deviated and non-deviated sides. Postoperatively (T2-T3), each reference point had no statistically significant positional change. Pearson correlation coefficient between the amount of menton deviation (ME-X at T1) and positional change of menton after surgery (T2-T3) was 0.30, and P value was 0.168. The hybrid fixation technique is an effective fixation method for achieving postoperative stability for mandibular asymmetry.