Head posture and pharyngeal airway volume changes after bimaxillary surgery for mandibular prognathism.

PURPOSE: The purpose of this study was to evaluate head posture and the pharyngeal airway volume changes using 3D imaging after bimaxillary surgery in mandibular prognathism patients by null hypothesis. MATERIALS AND METHODS: Cone-beam computed tomography (CBCT) scans were obtained for 25 mandibular prognathism patients before bimaxillary surgery (T1) and 6 months after surgery (T2). The head posture of each patient was assessed by measuring cranio-cervical angle on a midsagittal plane passing through the anterior nasal spine at T1 and T2. Additionally, the volume of each subject's pharyngeal airway was measured using InVivoDental 3D imaging software. RESULTS: The cranio-cervical angle increased significantly 6 months after bimaxillary surgery (p < 0.01). The total volume of the pharyngeal airway slightly decreased (p > 0.05) at the same timepoints, while naso- and oro-pharyngeal airway volume decreased significantly (p < 0.05, p < 0.05). There was significant relationship between the changes of head posture and those of total airway volume (p < 0.05). CONCLUSION: The null hypothesis was rejected. Bimaxillary surgery resulted in significant head flexion and a slight decrease in total pharyngeal airway volume.