Abstract:Objective To measure and analyze the effect of the amount of mandible setback on the oropharyngeal airway in patients with skeletal class III malocclusion. Methods Nineteen patients (13 females and 6 males) with skeletal class Ⅲ malocclusion were divided into two groups according to the amount of mandible setback. GroupⅠ(9 patients) had the amount of mandible setback less than 5mm and groupⅡ(10 patients) equal to or more than 5mm. All patients underwent bilateral sagittal split ramus osteotomy (BSSRO) for mandible setback. They received CT scanning and pulmonary function examination 1 week before and 3 to 6 months after surgery. Mimics 21.0 software was used for image processing and measurement, and SPSS 23.0 software was used for statistical analysis. Results In velopharynx, the values of both groupⅠand II were increased after surgery, but the differences were statistically insignificant (both P>0.05). In glossopharynx, the values of groupⅠand II were both decreased after surgery. The reductions of the cross-sectional areas and volumes in group II were more obvious than groupⅠ, and the differences were statistically significant (both P<0.05). Conclusion In orthognathic surgery, BSSRO causes significant reduction in the cross-sectional areas and volumes of the glossopharyngeal segment in patients with skeletal class III malocclusion, and the patients with greater amount of mandible setback may have more reduction.
