Volumetric, planar and linear airway comparison after maxillomandibular advancement surgery

Background and Objectives: Treatment of sleep apnea can be accomplished using both non-surgical and surgical methods. Surgical treatment is further classified into phase I and II surgery. When phase I treatment fails, orthognathic surgery is judged to be the subsequent step in treating these patients. Orthognathic surgery is considered phase II treatment and can consist of a maxillomandibular advancement (MMA)1-11. Until recently, most of the data gathered on patients how have had a maxillomandibular advancement has been completed using lateral cephalograms. The rationale for this study is to gain a better understanding of the alteration in linear, planar and volumetric posterior airway space following double-jaw advancement surgery with a counter-clockwise rotation of the occlusal plane. Methods: A total of 28 subjects pre- and post-surgical CBCT scans were evaluated. All of the individuals underwent a maxillomandibular advancement with a counterclockwise rotation of the occlusal plane. All DICOM files were analyzed using Dolphin 3D Imaging 11.5, licensed to West Virginia University Department of Orthodontics. The CBCT volume was used to create right lateral cephalograms which were then used for linear cephalometric measurements. The 3D volume was also utilized to find cross-sectional measurements from axial slices taken from the cone-beam images at specific points: PNS, CV1, CV2 and CV3. Finally, CBCT images were used to find volume measurements at explicit regions along the posterior airway space. Data was analyzed using a matched-pair test. Results: When all subjects were grouped together the p-value for the change in all variables was \u3c0.05. This indicates that there was a statistically significant change in all variables regardless of the method used to evaluate pre- and post-surgery changes. It also suggests that although CBCT is a valuable tool to evaluate airway change, cephalometric radiographs can be used to determine whether change in PAS is significant when it pertains to maxillomandibular advancement surgery. Conclusions: The maxillomandibular advancement procedure with or without genioplasty illustrated great increases in posterior airway space in both 2-dimensional and 3-dimensional analyses. However, more information was available in regards to site of airway obstruction when utilizing the 3D data in comparison to 2D. Patients with obstructive sleep apnea should be presented with the option of MMA surgery as a treatment option if CPAP is not tolerated or other therapies have failed