What is the influence of occlusal plane rotation in orthognathic surgery on upper airway volume?

This prospective observational study investigates whether changes in the direction and magnitude of occlusal plane angulation influence upper airway volume in adult patients undergoing orthognathic surgery.

Data were collected preoperatively and 7 days and 6 months postoperatively. Cone beam computed tomography (CBCT) was used to measure occlusal plane angulation and upper airway volume. All measurements were performed by a single, calibrated researcher trained by a gold standard specialist. Statistical significance was set at p < 0.05.

Forty-eight patients were included: 27 women (56,25%) and 21 men (43,75%), with a median age of 29 years (range 18-52). Skeletal classifications were as follows: 19 class II (39,58%), and 29 class III (60,42%). Occlusal plane rotation was counterclockwise in 24 patients (50%) and clockwise in 24 patients (52%). Rotational changes were minor (0-2°) in 24 cases (50%) and major (> 2°) in the remaining 24 cases. No significant differences were observed in rotation direction or magnitude between class II and III patients (p > 0.05).

Class II patients showed a significant increase in oropharyngeal volume (p = 0.026), while class III patients showed an increase in nasopharyngeal volume (p = 0.003), regardless of occlusal plane changes. Additionally, nasopharyngeal volume increased significantly in class III patients with clockwise (p = 0.035) and counterclockwise (p = 0.037) rotations.