Effects of bimaxillary surgery and mandibular setback surgery on pharyngeal airway measurements in patients with Class III skeletal deformities

Introduction: The purpose of this study was to compare the short-term and long-term effects of bimaxillary surgery with those of mandibular setback surgery concerning pharyngeal airway measurements at 3 levels: nasopharynx, oropharynx, and hypopharynx. Methods: The sample included 66 Japanese women in 2 groups who had been diagnosed with Class III skeletal deformities and had undergone surgical-orthodontic treatment. Those in group A (35 patients) underwent bilateral sagittal split ramus osteotomies; those in group B (31 patients) underwent LeFort I procedures with bilateral sagittal split ramus osteotomies. Lateral cephalograms were assessed within 6 months before surgery and at short-term (3-6 months after surgery) and long-term (at least 2 years after surgery) follow-ups. Results: In group A, the pharyngeal airway was constricted significantly at the oropharyngeal and hypopharyngeal levels at both the short-term and the long-term follow-ups. In group B, significant changes were shown at the 3 pharyngeal levels at the short-term follow-up, whereas no significant changes were shown at the long-term follow-up. Conclusions: These results indicate that, when possible, bimaxillary surgery rather than only mandibular setback surgery is preferable to correct a Class III deformity to prevent narrowing of the pharyngeal airway space, a possible predisposing factor in the development of obstructive sleep apnea.