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

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.