![]() ![]() ![]() ![]() Unfortunately, there has been a lack of research assessing the changes of the hyoid bone, tongue, and oropharyngeal airway space in patients treated solely with mandibular setback surgery. Therefore, clinicians need to understand the postoperative changes that follow mandibular setback surgery. However, isolated mandibular setback surgery is still the first choice in many cases with mandibular prognathism. Recently, the percentage of class III patients being treated with bimaxillary surgery has been increasing. reported that the incidence of mild-to-moderate obstructive sleep apnea syndrome was higher in patients with a mandibular setback of 5 mm or more than in the group with setback of less than 5 mm. Several cases of postsurgical OSA have been reported by some authors since the 1980s. Obstructive sleep apnea (OSA) is a common sleep disorder caused by airway collapse at multiple levels of the upper airway, resulting in airway obstruction. This posterior shift of the tongue base causes a posterior extension of the soft palate and creates an increase in soft palate contact length, which can consequently decrease the pharyngeal airway space (PAS). The posterior movement of the mandible induces positional changes of the hyoid bone and tongue base. Mandibular setback surgery is usually the treatment of choice for mandibular prognathism. Orthognathic surgery for skeletal deformity is the standard of care for improving esthetics, occlusal relationship and stomatognathic function. There were significant changes in the hyoid bone, tongue, and airway space after mandibular setback surgery. In addition, the amount of mandibular setback positively correlated with the amount of posterior and inferior movement of the hyoid bone ( P < 0.05, P < 0.05, respectively). The anteroposterior and transverse widths of the minimal cross-sectional area were decreased ( P < 0.001, P < 0.001, respectively). Regarding the velopharyngeal and glossopharyngeal spaces, there were significant reductions in the volume and minimal cross-sectional area ( P < 0.001). Significant superior and posterior movements of the tongue were observed ( P < 0.05, P < 0.05, respectively). The hyoid bone showed significant posterior and inferior displacement ( P < 0.001, P < 0.001, respectively). The mean age of the patients was 21.7 years and the mean amount of mandibular setback was 5.94 mm measured from the B-point. #INVIVO ANATOMAGE 5 DOWNLOAD SOFTWARE#The CBCT images were reoriented using InVivo 5.3 software (Anatomage, San Jose, USA) and landmarks were assigned to establish coordinates in a three-dimensional plane. MethodsĪ total of 30 pairs of cone-beam computed tomography (CBCT) images taken before and 1 month after surgery were analyzed by measuring changes in the hyoid bone and tongue positions and oropharyngeal airway space. The aim of this study was to analyze the 3-dimensional (3D) changes in the hyoid bone and tongue positions and oropharyngeal airway space after mandibular setback surgery. Surgical movement of the mandible affects the base of the tongue, hyoid bone, and associated tissues, resulting in changes in the pharyngeal airway space. Mandibular setback surgery can change the position of the mandible which improves occlusion and facial profile. ![]()
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