Relationship between temporomandibular joint disc position and configuration on magnetic resonance imaging

Magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ) has been shown to be of great value in the detection of displacements and delineation of the disc configuration in patients suspected of having internal derangements. The present study was conducted in temporomandibular joints of 144 patients in order to investigate whether an association exists between disc position, disc reduction and disc configuration as seen on MRI. Sagittal proton density-weighted MRIs of 288 TMJs (144 patients) were taken with the mouth closed and opened, and the position and configuration of the articular disc were assessed. The results showed that joints with a superior disc position barely demonstrated disc deformation while in joints with anteriorly displaced discs, disc deformation occurred more frequently (p<0.001). Non-reduction of the disc was associated with disc deformation whereas disc reduction was associated with the normal biconcave disc configuration (p<0.001). These data suggest that an association exists between disc displacement and disc deformation and between disc deformation and the degree of anterior disc displacement.