Anterior disc displacement without reduction in the temporomandibular joint: MRI and associated clinical findings

To determine the value of MRI in temporomandibular joint (TMJ) disorders, the data of MRI-proven anterior disc dislocation without reduction (ADWOR) were correlated with clinical history and clinical data. MRI demonstrated degenerative bony changes and a reduced sagittal diameter of the condyle, a variable degree of disc deformation, and a thinned bilaminar zone in each of the joints with ADWOR, which clearly differed from patients with anterior disc dislocation with reduction (ADWR) (P=.01) and normal disc position (NDP) (P <.001). Of 59 patients and 83 TMJs that had been investigated in a a-year period, as shown by MRI, 22 patients (27 TMJs) had ADWOR (32%), 16 joints had NDP (19%), and 40 patients had ADWR (49%). In patients with ADWOR, the clinical history revealed pain in either of the joints and/or cervical or masticatory muscles in 25 (93%) joints. Clinical investigation revealed various abnormalities in 22 joints; five of those presented without any pathologic clinical finding. Mouth opening was unlimited in nine patients (47%), palpation of the muscles of mastication was painless in 13 patients (52%), and joint noises during mouth opening or closing were noted in 14 patients (56%). According to clinical histories, four patients were suspected to have become symptomatic only after dental treatment. ADWOR is difficult to diagnose with clinical methods alone, The indication for MRI evaluation of the TMJ should be extended for asymptomatic patients with a history of limitation in mouth opening and pathologic x-ray morphology of the condyle. Because symptoms may arise after dental treatment in these patients, aggravation of internal derangement may be avoided by careful handling.