Alterations in upper airway dimensions following bimaxillary and mandibular setback surgery in skeletal Class III...

Orthognathic surgery can result in a decreased upper airway volume, potentially increasing the risk of developing sleep disorders. This study aimed to evaluate upper airway changes following bimaxillary orthognathic surgery and mandibular setback surgery alone. Additionally, to investigate any correlation between factors such as mandibular plane angle and mandibular length on airway changes in skeletal Class III patients, utilizing cone beam computed tomography (CBCT) data.

A total of 78 patients with maxillomandibular discrepancy ≤ -2 were divided to Group 1 (mandibular setback, n = 17) and Group 2 (maxillary advancement with mandibular setback, n = 61). CBCT scans were obtained 2-3 weeks preoperatively and 6 months postoperatively to measure airway volumes, minimal axial area, linear dimensions, and angles using Dolphin Imaging software. Statistical analyses, including the Wilcoxon signed-rank test and paired t-test, assessed pre- and postoperative effects, while Spearman's correlation evaluated the associations between variables and postoperative changes.

The results revealed a significant reduction in oropharynx volume (OPV), hypopharynx volume (HPV), total pharyngeal volume (TPV), and minimum cross-sectional area (CSA^min) following mandibular setback surgery, while bimaxillary surgery of mandibular setback with maxillary advancement resulted in significant decreases in nasopharynx volume (NPV), TPV, and CSA^min. Both surgical approaches caused narrowing of the anteroposterior length (APL) and significant constriction in the lateral transverse width (LTW) of the pharyngeal airway space, with Spearman's correlation indicating no significant relationships between these variables and postoperative changes.

Both types of orthognathic surgeries caused significant decreases in total airway volume, CSA^min and lateral airway dimension.