The Relationship Between Mandibular Movement and Condylar Resorption in Mandibular Advancement Surgery

INTRODUCTION: It is acknowledged that the degree of mandibular advancement exerts an influence on condyle resorption; however, there remains a paucity of data concerning the extent of resorption when the mandible is advanced. The objective of the present study was to investigate the change in condyle volume after mandibular advancement and to determine the amount of advancement causing resorption, if indeed such a phenomenon occurs. METHODS: In a retrospective study of cases involving mandibular advancement or double jaw advancement, with preoperative and postoperative CBCT images of adequate quality available in our hospital archive, condyle volumes were calculated by surface-based registration, semiautomated segmentation, and 3D modeling using ITK-SNAP software. RESULTS: The study was performed on 16 patients (32 condyles). Of the cases, 10 (62.5%) were classified as double jaw advancement, while 6 (37.5%) were classified as mandibular advancement. The mean advancement measurement was 5.6±1.4 mm on the right side and 5.8±0.9 mm on the left side. The condyle volume loss was found to be significant (P=0.01). A significant increase in resorption was observed when the advancement was 6 mm or more (P<0.05). CONCLUSION: In orthognathic surgery for class II malocclusion, condylar volume reduction has been found to be correlated with the amount of mandibular movement. It has been demonstrated that resorption increases significantly when the amount of advancement is 6 mm or more.