Bimaxillary Orthognathic Surgery for Facial Asymmetry with Near-Normal Sagittal Relationship: Mid-Term Stability and...

Background and Objectives: Mid-term skeletal stability after bimaxillary orthognathic surgery in patients with facial asymmetry and a relatively normal sagittal skeletal relationship (ANB ≈ 1-4°) remains underreported. This study aimed to determine the three-dimensional characteristics and temporal changes in postoperative skeletal remodeling and symmetry maintenance in such patients. Materials and Methods: This retrospective case series included 25 patients (ANB ≈ 1-4°) undergoing bimaxillary orthognathic surgery. Three-dimensional computed tomography was performed preoperatively (T0), immediately postoperatively (T1), and at 6-12 months postoperatively (T2) to quantify bilateral condylar, ramus, mandibular body, maxillary parameters, and occlusal cant. Statistical analyses were performed using appropriate statistical methods for paired and repeated-measures designs. Results: Preoperatively, the long side exhibited significantly greater condylar volume, ramus height, and mandibular body length than the short side (all p < 0.05). Postoperatively, a "long-side reduction and short-side augmentation" strategy significantly reduced or reversed most bilateral differences, with a marked improvement in occlusal plane cant (p < 0.01). At T2, only mild bone remodeling was observed, with no significant loss of postoperative skeletal symmetry. The occlusal plane remained stable. Conclusions: In patients without marked sagittal discrepancies, bimaxillary orthognathic surgery effectively restores transverse and vertical skeletal symmetry. Mid-term stability is well maintained over 6-12 months, with only mild condylar and ramus remodeling, suggesting adaptive remodeling rather than relapse.