Changes in condylar volume and joint spaces after orthognathic surgery.

The aim of this study was to evaluate the changes in condylar volume and joint spaces occurring in patients undergoing bimaxillary orthognathic surgery for the treatment of class II deformities, by means of cone beam computed tomography (CBCT). Initial and follow-up (at least 6 months) CBCT examinations of 114 condyles (57 patients) were studied retrospectively. Linear measurements of the joint space and volumetric analysis of changes in condylar volume were performed using Dolphin 3D Imaging in association with ITK-SNAP 3.0.0 segmentation software. The paired t-test and Pearson correlation coefficient were applied, and a descriptive analysis was performed. Mean condyle volumes were significantly smaller at follow-up (P=0.0125). There were significant reductions in superior and medial joint spaces in the follow-up examinations (both P<0.05). Positive correlations were found when comparing the mean changes in anterior, superior, and posterior space values between the right and left sides. No significant correlation was observed between changes in volume and joint spaces. In conclusion, there was a reduction in mean condylar volume after orthognathic surgery in class II patients. However, changes in volume for each condyle may be variable. Such changes in condylar volume may occur independently on the left and right sides, and do not correlate with changes in joint spaces.