Relationships between disk displacement, joint effusion, and degenerative changes of the TMJ in TMD patients based on MRI findings.

This study was performed to investigate the relationships between disk displacement, joint effusion, and degenerative changes in patients with temporomandibular disorders using MRI. Randomly selected MRIs of 508 temporomandibular joints of 254 patients (92 males and 162 females, mean age was 30.5±12.0 years) were reviewed retrospectively. Seventy-eight percent (198 out of 254) of the patients complained of joint pain. Compared with joints with a normal disk position, the joints with anterior disk displacement with reduction showed a 2.01 odds ratio (P<0.01) of degenerative changes and a 2.85 odds ratio (P<0.001) of joint effusions. The joints with anterior disk displacement without reduction showed a 4.43 odds ratio (P<0.001) of degenerative changes and a 4.61 odds ratio (P<0.001) of joint effusions. These results clearly show that the risk of degenerative changes and joint effusions increase with displacement of the disk position in patients with temporomandibular disorders. Although all disk displacement situations do not progress to painful joints and/or degenerative joint diseases, the possibility of an increased risk of progression by a breakdown in the balance between a patient's adaptive capacity and functional loading of the TMJ should be assessed in each and every patient through comprehensive evaluation of various contributing factors.