Background: Internal derangement of the temporomandibular joint (TMJ) results in anterior disc displacement with reduction (ADDR), the disc is ante- riorly displaced in the closed position whereas in the opened position the disc returns to its normal location. In anterior disc displacement without reduction (AD- DWR), the disc is anteriorly displaced in the closed po- sition but does not return to its original location in the opened position. Here we studied and compared the effects of the ADDR and the ADDWR on the components of the TMJ by using the magnetic resonance imaging technique (MRI). Methods and materials: From the archival MRI records, 214 joints from 107 patients were included. The selec- tion criteria for the patients complaints as TMJ pain, clicking, limited mouth opening, headache, jaw tenderness and difficulty in eating. MRI records with sequences Proton Density (PD), PD FAT SAT and T2* gradient in the closed position and T2* gradient echo in the opened position. Data analysis and frequency distribution of explanatory variables by disc position in the open state was performed using chi-square test Results: Statistically significant differences were observed between the variables such as the joint space (closed position), disc morphology (closed position) and range of movement (opened position) among the ADDR and the ADDWR. In ADDWR, 20.3% demonstrated narrowed joint space and 1.6% with widened joint space, while in ADDR, 2.5% of joints had narrowed joint space and 0% widened joint space. Same was observed with abnormal disc morphology and rang of movement. Conclusion: The disc deformity is more in ADDWR compared to ADDR which can be seen as an alteration in the signal intensity. The malaligned disc could lead to the narrowing of the joint space and decreased range of movement in the ADDWR affected individuals.
Diagnostic reproducibility of temporomandibular joint using magnetic resonance imaging at 0.5 and 1.5 Tesla
