Effect of mono- and bimaxillary advancement on pharyngeal airway volume: cone-beam computed tomography evaluation.

PURPOSE To evaluate pharyngeal airway volume changes after forward movements of the maxilla or mandible, or both, using cone-beam computed tomography. PATIENTS AND METHODS A retrospective evaluation of 30 patients who underwent maxillomandibular advancement, maxillary advancement, or mandibular advancement was performed. Three groups of 10 subjects each were established: group 1, bimaxillary surgery (Le Fort I maxillary osteotomy and mandibular bilateral sagittal split osteotomy with maxillomandibular advancement); group 2, maxillary advancement (Le Fort I maxillary osteotomy); and group 3, mandibular advancement (bilateral sagittal split osteotomy). Pre- and postoperative cone-beam computed tomography scans were taken in each case, and the changes in pharyngeal airway volume were compared. RESULTS A statistically significant increase in the pharyngeal airway volume occurred systematically. The average percentage of increase was 69.8% in group 1 and 78.3% in group 3. Group 2 exhibited a lower magnitude of increase (37.7%). CONCLUSION Cone-beam computed tomography provides a new method for airway evaluation using a noninvasive, rapid, low-radiation, cost-effective scan. It seems the influence of mandibular advancement on the pharyngeal airway volume is greater than the effect of the forward movement of the maxilla.