The relationship of vertical skeletofacial morphology to oropharyngeal airway shape using cone beam computed tomography: possible implications for airway restriction.

OBJECTIVE: To determine if the shape of the oropharyngeal airway is related to the vertical morphology of the skeletofacial complex, including the hyoid bone. MATERIALS AND METHODS: Cone beam computed tomography scans from 50 pretreatment adult orthodontic records were used to obtain skeletal and airway measurements. Linear regression statistics were used to compare soft tissue variables to hard tissue predictor variables. RESULTS: Transverse airway widening was significantly increased when the distance between the hyoid and vertebrae was reduced; when the three-dimensional (3D) facial axis angle decreased (became more vertical); when the 3D mandibular plane angle increased; when the width of the hyoid increased, or when the calculated length of the geniohyoid decreased. CONCLUSIONS: A laterally elliptical airway-found when the face is more vertical and when the hyoid is closer to the cervical vertebrae-is hypothetically more resistant to collapse. Patients with a retrognathic, skeletal deep bite and a rounded oropharynx should be identified and corrected early to prevent potential airway problems.