Orthodontic treatment improves magnetic resonance imaging features and quality of life in adult patients with temporomandibular disorders.

Objective: This research intends to clarify the magnetic resonance imaging (MRI) features as well as changes in symptoms and quality of life (QoL) in adult patients with temporomandibular disorders (TMDs) before and after orthodontic treatment.

Methods: Clinical data of 57 TMD patients before and after orthodontic treatment were collected and analyzed retrospectively. The anterior and posterior regions of the temporomandibular joint (TMJ)'s articular disc were checked before, during and after the treatment by MRI, and the anterior and posterior spaces of TMJ were measured with an electronic measuring ruler. Pre- and post-treatment alterations in the Visual Analogue Scale (VAS) score, TMJ clicking, maximum mouth opening (MMO), and Fricton's indexes (TMJ dysfunction index, DI; palpation index, PI; craniomandibular index, CMI) of the patients were comparatively analyzed. The Oral Health Impact Profile questionnaire was employed for QoL assessment before and after treatment.

Results: On MRI, patients with TMDs presented clear changes in TMJ disc position, morphology, thickness and joint effusion, while those with pain symptoms also had condylar degeneration. In addition to a reduced VAS score, the line distance of the TMJ anterior space increased significantly, while the posterior space line distance decreased significantly after treatment, as compared with the baseline (before treatment). Before orthodontic treatment, a total of 46 TMD patients were accompanied by associated TMJ clicking, including 8 severe cases and 38 mild cases. The clicking disappeared in 39 cases after treatment, but mild unilateral clicking, mild bilateral clicking, and severe clicking were still observed in 5, 1, and 1 case(s), respectively. The patients exhibited an increase in MMO and a decrease in Fricton's indexes with significantly enhanced QoL after the orthodontic treatment.

Conclusions: Patients with TMDs exhibit diverse clinical features, and MRI can accurately reflect changes in the position, morphology and thickness of the articular disc as the disease progresses, which can improve the accuracy of clinical diagnosis. In addition, orthodontic treatment for TMD patients can effectively alleviate adverse clinical symptoms and improve their QoL.