Background and Aims :The most frequent cause of TMJ dysfunction is internal derangement which that largely involves  the function of the articular disc. Anterior disc displacement (ADD) is one of the major findings in TMJ internal derangement.
Since the importance of knowledge of its etiology and also The role of all structural indicators association with TMD was not evaluated, in this research was investigated Correlation between  TMJ structure and disc displacement.
Materials and Methods: This study was done based on case-control method. 31 Joints  with TMJ internal derangements and 57 normal joint Were examined. The two groups of clients were matched in age, sex , Economic and social situation. MRI finding was Disk position in Open and closed mouth and  condyle morphology coronal and axial view.MRI findings were Disk position in Open and closed mouth and  condyle morphology coronal and axial view. The data were analyzed using  x2 and Fisher's test.
Results: Patients with  TMJ internal derangement (ID), In all three groups  inchiding disk displacement with reduction(DDWR), disk displacement without reduction(DDWOR), anterior disc displacement(ADD), was encountered more frequently in Anterior, Anterior-inferior disk position in closed mouth,A statistically significant correlation was found( P 0.001> ). Also no significant difference was found in measurements between the three groups, for condyle morphology  in coronal and axial view. ( P > 0.4)
Conclusion: It seems there is relationship between Anterior disc displacement (ADD) and Anterior, Anterior-inferior disk position in closed. But There is no obvious relationship between Anterior disc displacement (ADD)  And  condyle morphology coronal and axial view