Pharyngeal Airway Space and Hyoid Bone Positioning After Different Orthognathic Surgeries in Skeletal Class II Patients

Abstract

To obtain good profiles, patients with severe skeletal Class II malocclusion require orthognathic surgery, which might change their airway space and, hence, influence their quality of sleep. The present study aimed to 1) determine the effect of different orthognathic surgeries on pharyngeal airway space and hyoid bone position in patients with skeletal Class II malocclusion and 2) evaluate the stability of changes in the pharyngeal airway space and hyoid bone position after orthognathic surgeries. Patients with severe skeletal Class II malocclusion who underwent mandibular advancement (MA) or mandibular advancement and maxillary setback (MAMS) were included in this retrospective cohort study. Changes in the pharyngeal airway space and hyoid bone position were evaluated as the primary outcome variables. Measurements were obtained before surgery (T1), 1month after surgery (T2), and 2years after surgery (T3) using Dolphin Imaging Software 11.0. Differences in measurements between T2 and T1 and between T3 and T1 were calculated and imported into SPSS 22.0 for data analysis. Fifty patients were included (25 in MA group and 25 in MAMS group). Oropharyngeal and hypopharyngeal airway cross-dimensions and areas were significantly increased in the MA group (P<.05) and the increases were stable at T3. In the MAMS group, the nasopharyngeal airway cross-dimension and area were decreased (P>.05), but the hypopharyngeal cross-dimension and area were significantly increased (P<.05). The hyoid bone moved superiorly and forward after surgery in the MA group (P<.05), and the movement was stable at T3. MA can widen the oropharyngeal and hypopharyngeal airway space, and maxillary setback can narrow the nasopharyngeal airway space. Some relapse related to the width of the oropharynx and hypopharynx was found at the long-term observation. The hyoid bone moved superiorly and forward in the MA group.