Bone Changes in Mandibular Condyle of Temporomandibular Dysfunction Patients Recognized on Magnetic Resonance Imaging

We aimed to investigate the type of bone changes in temporomandibular disorder patients with disc displacement. The subjects were 117 temporomandibular joints that were diagnosed with anterior disc displacement using magnetic resonance imaging (MRI). Temporomandibular joint (TMJ) pain and opening dysfunction were examined. Disc displacement with and without reduction, joint effusion, and bone changes in the mandibular condyle were assessed on MRI. The types of bone changes were classified into erosion, flattening, osteophyte, and atrophy on the MR images. Fisher's exact test and χ² test were performed for analyses. Bone changes were found on 30.8% of subjects with erosion, flattening, osteophyte, and atrophy types (p < 0.001). The occurrence of joint effusion appearance (p < 0.001), TMJ pain (p = 0.027), and opening dysfunction (p = 0.002) differed among the types of bone changes. Gender differences were also found among the types of bone changes (p < 0.001). The rate of disc displacement with reduction was significantly smaller than that of disc displacement without reduction on flattening and osteophyte (p < 0.001). The results made it clear that the symptoms, gender, and presence or absence of disc reduction differed among the types of bone changes.