The relationship between bimaxillary orthognathic surgery and the extent of posterior airway space in class II and III patients – A retrospective three-dimensional cohort analysis

Abstract

ObjectiveTo assess the relationship between bimaxillary orthognathic surgery in class II and III patients, the three-dimensional extent of the posterior airway space (PAS) using cone-beam computed tomography (CBCT). MethodsA retrospective evaluation of a cohort of Class II and III patients, who had undergone orthognathic surgery (Le Fort I osteotomy, bilateral sagittal split osteotomy), between December 2011 and July 2014, was performed. In each case, CBCT scans were performed one week prior (T1) to and 6 months (T2) after surgery, followed by analysis of several airway parameters (volume, mean cross-sectional area, and diameter) and the three-dimensional extent of mandibular movement. ResultsIn Class II patients significant postoperative volumetric increases in the middle and lower PAS segment as well as in all diametric and spherical variables (p ≤ 0.001) could be seen. In Class III patients there were only significant postoperative increases in the volumetric, and partially in diametric and spherical, variables (p < 0.05) of the upper PAS segment. There was also a significant linear relation between forward displacement of the maxilla and mandible and some airway parameters (p < 0.05). ConclusionsThese results reveal that bignathic surgery in Class II patients provokes an increase in most dimensions of the PAS. This intervention can be assumed to reduce airway resistance and might therefore be a suitable treatment option for patients suffering from OSAS. For bignathic surgery in Class III patients, a positive effect could be seen, especially at the nasopharynx.