Three-dimensional evaluation of changes in the upper airway, natural head position and hyoid bone position in skeletal Class Ⅲ patients after bimaxillary surgery

Objective To assess short- and long-term changes in the upper airway, natural head position and hyoid bone position in skeletal Class Ⅲ patients after bimaxillary surgery. Methods In this retrospective study, the cone-beam computed tomography(CBCT) of skeletal Class Ⅲ patients was taken before surgery(T0), 3 months after surgery(T1) and 2 years after surgery(T2). Three-dimensional images were created to assess postoperative changes and the correlation between the upper airway, natural head position and hyoid bone was analyzed. Results Thirty skeletal Class Ⅲ patients(13 men and 17 women) who underwent bimaxillary surgery with a mean(SD)age of 21 years(a range of 17-30 years)were evaluated. A significant decrease was observed in the volume of palatopharynx, glossopharynx and total airway after T1 and T2. There was a significant correlation between changes in the position of the mandible and changes in the volume of the upper airway(P