Three-Dimensional Analysis of Long-Term Stability After Bilateral Sagittal Split Ramus Osteotomy Fixed With a Single Miniplate With 4 Monocortical Screws and 1 Bicortical Screw: A Retrospective 2-Center Study

Purpose This study evaluated the long-term stability of bilateral sagittal split ramus osteotomy fixed with a single miniplate with 4 monocortical screws and 1 bicortical screw (hybrid technique [HT]) using 3-dimensional (3D) analysis and an objective measuring tool, cone-beam computed tomography (CBCT). Materials and Methods Sixty-four patients who underwent bimaxillary surgery with mandibular advancement fixed with the HT were selected from 2 different institutions and enrolled in this retrospective study. All patients underwent CBCT preoperatively, 1 month after surgery, and 12 months after surgery. To estimate the long-term stability of the HT, volumetric comparisons were performed using the following measurements: distance between the gonion and the B point in the sagittal plane; distance between the right and left gonion transversally; and the angle of the line connecting the mandibular notch and the gonion and the line connecting the gonion and the B point vertically. Results Statistical analysis showed no relevant relapse (<1 mm or <1°) when using the HT. However, a positive correlation between the amount of advancement and the amount of postoperative relapse was observed. Conclusion The HT produces stable postoperative 3D results after 12 months.