Patterns of osseous healing and remodelling after intraoral vertical ramus osteotomy

The intraoral vertical ramus osteotomy (IVRO) is a widely used for mandibular prognathism, offering segmental mobility, lateral overlap, immediate repositioning of the proximal segment, and direct cortex-to-cortex contact between the segments. Unlike the sagittal split ramus osteotomy, IVRO provides a dynamic healing environment with unrestricted segment movement. This retrospective study was performed to analyze the osseous healing and remodeling patterns following IVRO, using CBCT. CBCT images obtained at 1 month and 1 year postoperatively were assessed to evaluate osseous union and segment overlap. At 1 month postoperative, complete osseous union was significantly more frequent in rami with an intersegmental gap ≤1.5 mm compared to those with a gap >1.5 mm (P = 0.002 and P = 0.003, for the two planes of observation). There was no significant relationship between the type of overlap pattern at 1 month postoperative and osseous union at 1 year postoperative. A significant positive correlation was observed between the intersegmental gap at 1 month postoperative and total ramus width at 1 year postoperative; total width increased by approximately 0.55 mm for every 1-mm increase in intersegmental gap (P = 0.008). The study findings suggest that maintaining a gap below the critical threshold of 1.5 mm enhances osseous healing.