Changes in pharyngeal airway space and hyoid bone positions after body osteotomies and sagittal split ramus osteotomies

Abstract

Although mandibular setback might lead to possible pharyngeal narrowing, the development of obstructive sleep-related breathing disorders may occur because of multiple factors. In this study, the changes in the pharyngeal airway space (PAS) and the hyoid bone position have been evaluated before and after surgery in patients who underwent body ostectomy (BO) and sagittal split ramus osteotomy (SSRO). In addition, the effects of the BO on PAS and on hyoid bone position have been compared with the effects of the SSRO. Material and Methods: Thirty patients with mandibular prognathism underwent mandibular setback osteotomy. The patients were divided into two groups: BO group, 15 patients (5 men, 10 women) who underwent BO; and SSRO group, 15 patients (11 men, 4 women) who underwent SSRO. Changes in PAS and hyoid bone position were analyzed throughout the preoperative and early and long-term postoperative periods via lateral cephalometric radiographs. Results: A decrease has been observed in the PAS area and the anteroposterior dimension of the PAS detected in all patients in the long-term period. Hyoid bone revealed backward and downward movement during the early postoperative period; however, it showed a tendency to return to its original anatomic position during the long-term postoperative period. None of the patients had disturbances in respiration. Conclusion: After BO and SSRO, a decrease in PAS area was observed, and this decrease also continued in the long-term period. Our results revealed a decrease in PAS area after BO, but the decrease was less than that in cases having SSRO.