Corrective outcome and transverse stability after orthognathic surgery using a surgery-first approach in mandibular prognathism with and without facial asymmetry

Objectives. The aim of this study was to evaluate corrective outcome and transverse stability after orthognathic surgery via a surgery-first approach (SFA) in mandibular prognathism with and without facial asymmetry using 3-dimensional analysis. Study Design. Twenty-nine patients who received mandibular setback surgery using SFA were divided into 2 groups according to the menton deviation (4 mm): symmetry group (n = 17) and asymmetry group (n = 12). Using computed tomography images obtained before (T0), immediately after (T1), and 6 months after (T2) surgery, time-dependent changes in variables related to facial asymmetry, including maxillary height, ramal length, frontal and lateral ramal inclination, mandibular body length, and mandibular body height, were evaluated. Results. Immediately after surgery, the asymmetry group showed significantly decreased discrepancies between the longer and non-longer sides for all variables (P < .05); there were no significant differences in discrepancies between the 2 groups. During the postoperative period, no significant changes in discrepancies were found in any variable in either group. Compared with T0, the asymmetry group showed significantly decreased discrepancies in ramal length, frontal and lateral ramal inclination, and mandibular body length at T2. Conclusions. Variables related to facial asymmetry showed significant improvement after surgical-orthodontic treatment using SFA, and corrected outcomes showed good postoperative stability in both the symmetry and asymmetry groups.