Changes of the temporomandibular joint following combination of orthognathic surgery and orthodontics of skeletal Class III malocclusion on radiography

Objective To investigate the effects of combination of orthognathic surgery and orthodontics for skeletal Ⅲ malocclusion on the position and configuration of temporomandibular joint (TMJ) with radiography. Methods Thirty patients with skeletal Angle Class Ⅲ malocclusion were studied. The patients treated with pre-operative orthodontics, bilateral sagittal split ramous osteotomy (BSSRO) and post-operative orthodontics were studied clinically and radiographically in three different phases in order to locate the position of the temporomandibular joint in relation to the glenoid fossa. Results ① Changes of temporomandibular joint space: the joint space changed one month after operation(P 0.05),and returned to the original position 6-12 months after operation(P 0.05).②Changes of condylar position and glenoid fossa configuration: the condylar positions changed one month after operation(P 0.05). The condylar positions shifted backward in sagittal and moved down in vertical,and returned to the original position 6-12 months after operation(P 0.05). The glenoid fossa configuration was not changed (P 0.05). ③Abnormal joint sound disappeared in five of nine patients with abnormal joint sound before surgery,and there was not any new case of abnormal joint sound after the sugery. There were no temporomandibular disorders (TMD)in all of the 30 patients preoperatively and postoperatively. Conclusion ①The effects of combination of orthognathic surgery and orthodontics on TMJ space is obviously changed,and most of the changes are within the normal adaptability of TMJ. The joint space and condylar position have been changed one month after BSSRO,and returned to original position 6-12months after BSSRO. The glenoid fossa configuration is not changed. ②None of the patients leads to TMD,and abnormal joint sound disappears in some of nine patients with joint sound before surgery. Therefore it suggests that orthodontic-orthognathic therapy has a certain efficacy in the treatment of TMD.