3D analysis of long-term airway evolution following orthognathic approach of bimaxillary setback surgery without segmental osteotomy

Long-term evolution of airway space following bimaxillary setback surgery has been seldom reported. 31 patients with bimaxillary protrusion were included in this study. Bimaxillary setback surgery without segmental osteotomy were performed to alleviate their facial deformity. The pharyngeal airway volume and most constricted airway cross-sectional areas before surgery (T0), one week (T1), and one year (T2) after surgery were measured by 3D image analysis depending on CT data. To exclude the impact of post operational swelling on the airway analysis, the airway changes of another cohort of 10 orthognathic patients without sagittal maxilla or mandible movements were also measured as a control. Body mass index (BMI) was noted and analyzed as well to rule out its interference. Results showed that, in bimaxillary setback surgery patients, no post operational upper pharyngeal airway sleep disorders (UASD) occurred. The mean +/- SD of pharyngeal airway volume (PAV) and the minimum cross-sectional area (Min-CSA) at T0 were 14921.3 +/- 3910.1 mm(3) and 147.9 +/- 75.8 mm(2), reduced to 11834.1 +/- 3916.3 mm(3)(79.3%, P < 0.001) and 111.6 +/- 60.6 mm(2)(75.4%, P < 0.001 at T1, and recovered to 14686.8 +/- 3917.1 mm(3)(97.1%, P < 0.001) and 132.7 +/- 62.8 mm(2) (89.6%, P < 0.001) at T2. In control group patients, the mean +/- SD of PAV were 16540 +/- 5518 mm(3) at T0 vs 14248 +/- 4340 mm(3) at T1 (P = 0.051) and Min-CSA were 156 +/- 61 mm(2)(T0) vs159 +/- 61 mm(2) at T1 (P = 0.849). Besides, At T0 and T2, the mean +/- SD of the BMI was 20.19 +/- 1.80 and 20.04 +/- 2.53 respectively (P = 0.772). This study suggests that Orthognathic bimaxillary setback reduce the pharyngeal airway space. However, the reduction will largely alleviate in long-term. Aesthetic oriented bimaxillary setback approach is relatively safe when the setback distance is controlled appropriately.