Hyoid bone position and airway changes after orthognathic surgery in skeletal class 3 patients 3D analysis

Objective: The aim of this study was to evaluate the changes in pharyngeal airway dimensions and hyoid bone position after orthognathic surgery. Material and method: total of 43 (25 female, 18 male) adult subjects were used in our study to evaluate the airway after orthognathic surgery in Class III patients. The patients were divided into 2 groups. Maxillary advancement, mandibular retraction and genioplasty were performed in the CC+G group, and maxillary advancement and mandibular retraction were performed in the CC group. CBCT records were obtained before surgery (T0) and at least 6 months after surgery (T1). All CBCT data were analyzed with Ondemand 3d software: pharyngeal volume, minimum axial area, and hyoid bone position measurements were compared within and between groups. Correlation analysis was performed between parameters. Results: In both groups, NFH increased significantly (p<0.05), whereas OFH and MAA values did not change. In addition, no significant decrease in postoperative airway volumes was observed in all patient groups in our study. Hypopharyngeal volume (HFH) and the distance between the Hyoid-Retrognathion were significantly increased in the CC+G group (p<0.05), while the distance between H-MAN increased and the distance between H-C3 decreased in both groups. These findings were not statistically significant. Conclusion: In the planning stage of orthognathic surgery, especially in cases of severe mandibular prognathism, it is important to evaluate the changes that will occur in the airway in 3D before the operation and to determine the amount of surgical movement by considering both function and aesthetics in order to maintain healthy respiratory function after the operation. Key Words: Orthognatic surgery, hyoid bone, pharyngeal airway, upper airway, cone beam computed tomography (CBCT).