Evaluation of postoperative stability of the mandibular midline widening osteotomy technique with concurrent genioplasty for correction of bimaxillary transverse discrepancy.

Objectives: Mandibular midline widening is a known technique to correct transverse deficit. The osteotomy can be combined with bimaxillary orthognathic surgery and genioplasty in patients who require surgical correction of mandibular transverse width. The purpose of this study was to assess postoperative stability in patients who underwent bilateral sagittal split ramus osteotomy (BSSRO) setback and widening of mandibular midline to reinstate ideal transverse width.

Patients and methods: This retrospective cohort study included patients wherein single stage Le Fort I, BSSRO setback with mandibular midline widening and genioplasty was performed within August 2020 to March 2024; 24 patients underwent surgery and a 6-month postoperative follow-up. Three patients requiring surgery first approach, two stage bimaxillary surgery and titanium osteosynthesis placement without genioplasty were excluded (n=21). Pre- and postoperative radiographs at specific timepoints were used to compare same landmarks at the first molar and gonial regions, representative of mandibular transverse width change. Condylar angulations were assessed once before and after surgery. Postoperative complications were assessed during follow-up. Statistical analysis was done using Friedman's test, Wilcoxon signed rank test, t-test and Spearman's correlation. P<0.05 indicated significance.

Results: Total sample consisted of 21 (10 male, 11 female) patients. Mean patient age was 27.9±10.8 years. Simulated preoperative widening mean was 3.23±0.76 mm. There was no statistical significance between postoperative immediate and 1-month, 3-months, 6-months widening at gonial region; molar widening showed significance at 6-months (P=0.03). Molar widening correlation to right and left condylar angulation had very weak relation to both condyles in the immediate postoperative period. One patient sustained gingival tear and plate exposure which healed eventually.

Conclusion: BSSRO setback with mandibular midline widening and genioplasty is ideal for correction of mild to moderate (≤5 mm) transverse mandibular discrepancies with good stability and fewer postoperative complications.