Effects of mandibular advancement surgery combined with minimal maxillary displacement on the volume and most restricted cross-sectional area of the pharyngeal airway.

The purpose of this study was to evaluate changes in the volume and most restricted cross-sectional area of the pharyngeal airway as a result of mandibular advancement surgery with minimal maxillary displacement, and to ascertain the change in height of this restricted area and whether gender and age could influence these results. Cone beam computed tomography scans were obtained from 25 patients (seven male and 18 female, average age 35.5 years). The measurements were done using the InVivoDental software (version 5.0). Comparisons were made between measurements taken prior to treatment (T1) and postsurgery (T2, average 6.3 months after surgery). No variation was detected on the scans with regard to head position, which could influence the pharynx airway. Surgery significantly increased the pharynx airway volume at the total (P<0.0001), upper (P=0.0001), and lower (P<0.0001) levels, with respective enlargements of 54.5%, 37.0%, and 91.3%. Gender and age did not influence this increase. A significant enlargement in the minimum area of the pharynx airway was detected (P<0.0001), which changed in shape from a tapering to a rounded shape. Using binomial and multiple logistic regression tests, this constricted site presented an unpredictable change in position as a result of surgery, with no association to gender (P=0.0745) or age (P=0.5879).