Oropharyngeal airway volume changes: A 3-dimensional evaluation using cone-beam CT in combined orthodontic-orthognathic surgery patients, Melissa Kathryn Roehm Stigall, Saint Louis University, St Louis, Mo

Abstract

Introduction: Advances in oral surgery have made combined orthodontic-orthognathic treatments more desirable for patients with skeletal and dental discrepancies. With our ability to move the skeletal tissue in many directions, skeletal movement can also influence the shape and area of the surrounding soft tissues, particularly the pharyngeal airway. For postsurgical changes, little focus has been placed on the effect of interior soft tissues and the airway. The purpose of the study was to evaluate the volumetric changes of the pharyngeal airway after mandibular surgery by using cone-beam computerized tomography (CT). The null hypothesis was that an increase in the pharyngeal airway volume of patients after mandibular surgery will not occur. The hypothesis will be rejected if pharyngeal airway volumes increase significantly after orthognathic surgery. Methods: Records of 15 consecutively treated patients who underwent orthognathic surgery for treatment of skeletal discrepancies were evaluated. Patients were grouped based on type of mandibular surgery performed: mandibular advancement or mandibular setback. Presurgical and postsurgical scans were made by using the i-Cat cone-beam CT unit. The postsurgical scan was made within 8 weeks. Reformatted 3-dimensional images were made and evaluated by using V-Works 4.0 software (CyberMed, Seoul, Korea) and the beta version of Dolphin 3D (Chatsworth, Calif). Significance testing was done with the Wilcoxon signed rank test. Results: The average changes in pogonion, as measured by using Frankfort horizontal to nasion perpendicular, were +3.45 mm in the advancement group and −2.93 mm in the reduction group. The mean overall pharyngeal airway volume tended to decrease after mandibular setback surgery, whereas the mean overall pharyngeal volume increased after mandibular advancement surgery. No significant differences were found in pharyngeal volume in any of the groups tested. Conclusions: This study indicates that there was no significant change in the volume of the pharyngeal airway in either surgical group after orthognathic surgery. These findings are consistent with the hypothesis that no change in volume would be expected after surgical movement of the mandible.