Evaluation of the effect of bimaxillary, mandibular setback, and advancement surgeries on the pharyngeal airway space and positions of the hyoid bone, soft palate, and tongue

Abstract

Introduction: This study aims to assess the postoperative changes in the pharyngeal airway space and the positions of the hyoid bone, soft palate, and tongue after mandibular advancement, mandibular setback, and bimaxillary surgeries. It also aims to compare the effects of mandibular setback and bimaxillary surgeries in the treatment of skeletal Class III patients. Materials and method: Lateral cephalograms of the patients were taken preoperatively and in a period of 3 months postoperatively on 21 subjects (3 groups, 7 patients each) who underwent mandibular setback surgery, bimaxillary surgery for Class III correction, and mandibular advancement surgery, respectively. Pre- and postoperative evaluation of skeletal and soft tissue landmarks were conducted to study the dimensions of the pharyngeal airway space and the position of the hyoid bone, soft palate, and tongue. Results: A significant increase in the oropharyngeal airway was observed after mandibular advancement surgeries, with an uprighting of the soft palate and anterior positioning of the tongue. In the mandibular setback group, the nasopharyngeal airway dimension increased significantly, and the hyoid bone was repositioned posteroinferiorly with posterior movement of the tongue. After bimaxillary surgery in Class III subjects, the nasopharyngeal airway space increased significantly associated with postural changes in the soft palate. Conclusion: Mandibular advancement surgeries can provide conditions for increased airway patency. With regard to the PAS, in Class III patients, maxillary advancement should be preferred to mandibular setback. When mandibular setback is indispensable, the association of movements in bimaxillary surgery can neutralize or minimize the effects of the setback.