Influence of maxillary clockwise rotation with posterior impaction and mandibular setback by SSRO or IVRO for mandibular prognathism on volume change in upper airway.

PURPOSE: In orthognathic surgery for skeletal mandibular prognathism, maxillary clockwise rotation with posterior impaction and mandibular setback is often performed. Change in airway volume after orthognathic surgery is one of the concerns. The present study was performed to evaluate the effects of maxillary clockwise rotation with posterior impaction and the influence of different mandibular techniques, including sagittal splitting ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), on upper airway volume changes before and after bimaxillary surgery for mandibular prognathism.

METHODS: We retrospectively investigated the amount of maxillary and mandibular movement and the changes on upper airway volume before and after surgery in 20 patients with mandibular prognathism who underwent bimaxillary surgery. Subjects were divided into Le Fort Ⅰ osteotomy (LF) +SSRO (n = 10) and LF+IVRO (n = 10) groups.

RESULTS: Comparing changes in nasopharyngeal, hypopharyngeal and pharyngeal volumes before and after surgery, reductions in airway volume were significantly smaller with LF+SSRO than with LF+IVRO. Although not significant, a correlation trend was observed between maxillary impaction and increased hypopharyngeal and pharyngeal volume in LF+SSRO. In LF+SSRO, correlations were observed between mandibular setback and reduction in hypopharyngeal and pharyngeal volume.

CONCLUSION: For posterior impaction and clockwise rotation of the maxilla with advancement and mandibular setback, LF+SSRO showed less change in postoperative upper airway volume than LF+IVRO and may be expected to reduce airway narrowing.