Abstract:Objective To investigate the changes of the articular disc and capsule in middle-aged and elderly patients with temporomandibular disorders（TMD）induced by distal-extension edentulism using magnetic resonance imaging, and to provide a theoretical basis for the diagnosis and treatment of TMD. Methods In this study, the MRI images of63 middle-aged and elderly patients with TMD who were treated in the Fourth Affiliated Hospital of Nanjing Medical University from 2021 to 2023 were selected, and the patients were divided into unilateral-defect group, bilateral-defect group, and non-defect group based on the distal-extension edentulism in clinical examination, and the changes of the joint disc and joint capsule of the temporomandibular joint of the three groups were compared. Results One-way ANOVA showed that there were significant differences in height and area of articular disc, area of anterior capsule, height and area of articular disc posterior capsule among three groups（P＜0.05）. There were significant differences in area of articular disc and height of anterior capsule between the non-defect group and the unilateral-defect group（P＜0.05）.The height and the areas of the articular disc, anterior joint capsule, and posterior joint capsule in the bilateral-defect group were significantly lower than those in the non-defect group or the unilateral-defect group. Conclusion Double distal-extension edentulous may lead to a decrease in the height and area of the joint disc in patients with TMD, and lead to a decrease in the area of the joint capsule.