Effects of mandibular setback surgery on oropharyngeal airway and arterial oxygen saturation

The aim of this study was to determine the effects of mandibular setback surgery on craniofacial and pharyngeal morphology and on respiratory function during sleep. The subjects were 17 patients in whom skeletal class III malocclusions were corrected by bilateral sagittal split ramus osteotomy. Arterial oxygen saturation (SpO2) during sleep was measured by pulse oximetry, and morphological changes were studied using cephalograms. The mean posterior movement of the mandible at surgery was 8.6mm at the pogonion, and many morphological and functional changes occurred with mandibular setback. Although there was no significant change at the oropharyngeal airway, significant protrusive head position and inferior displacement of the hyoid bone were seen postoperatively. Decreased SpO2 during sleep was found just after surgery, but had improved 1 month after surgery. It seems that almost all of the subjects adapted to the new environment in respiratory function during sleep, but patients with obesity, potential sleep-disordered breathing and a large amount of setback may suffer from obstructive sleep apnea (OSA) in the future. Careful postoperative follow up is needed for patients who have undergone mandibular setback surgery, and a strategy to prevent obstructive sleep apnea after mandibular setback surgery is needed.