Computed tomography visualizing alterations in the upper airway after orthognathic surgery

Three-dimensional (3D) software has revolutionized planning in orthognathic surgery. This technology allows the simulation of surgical movements and evaluation of the volume and area of the pharyngeal airway space (PAS), which are not possible with two-dimensional (2D) software. Many patients undergo orthognathic surgery to improve occlusion and facial profile. The PAS may increase or decrease depending on the surgical movements. This study aimed to evaluate the changes in the area and volume of the PAS in patients having bimaxillary movement in orthognathic surgery. The minimum axial area and volume of the PAS (preoperative (T0) and postoperative (T1) air volumes) of 68 patients (26 male and 42 female, mean age 36.6 ± 12.1 years) were analyzed. Evaluations were conducted using cone-beam computed tomography in the Nemoceph 3D-OS program. A paired t-test was used to compare pre- and postoperative volume data, and the Wilcoxon test was used to compare pre- and postoperative data of the minimal axial area. All the tests were performed with Statistica software (StatSoft Inc., Tulsa, OK, USA), and a significance level of 5% was adopted. In the study of the method error, no casual or systematic error was found between the first and second measurements of the variables (p > 0.05 in all measurements). Bimaxillary surgery presented a mean of 70.46% in volume and a median increase of 61.27% in the minimum axial area, which varied from -22.50% to 659.06%. The results demonstrated that bimaxillary advancement significantly increased the volume and minimum axial area of the upper airway; however, the increase was not homogeneous in all the patients.