Upper airway morphologic changes after mandibular setback surgery in skeletal class III malocclusion patients measured using cone beam computed tomography superimposition.

This study used the superimposition of cone beam computed tomography (CBCT) images to evaluate three-dimensional morphologic changes in the upper airway space of skeletal class III malocclusion patients with normally positioned maxilla who had undergone mandibular setback surgery. The upper airways of 18 subjects (10 males and eight females) who underwent mandibular setback surgery were assessed using CBCT superimposition at T0 (2weeks before surgery) and T1 (1year after surgery) according to the cervical vertebrae 1 (CV1), CV2, CV3 and CV4 reference planes on CBCT. The cross-sectional area and anteroposterior width (APW) in the CV1 and CV2 planes had significantly decreased at 1year after surgery. The largest decrease was observed in the oropharynx area. However, the APW/transverse width in the CV2 plane had increased at 1year after surgery. These findings suggest that mandibular setback surgery can cause a reduction in the upper airway space; physiologic deformation of the oropharynx occurs after mandibular setback surgery.