Magnetic resonance evaluation of the temporomandibular joint disc position and configuration.

Although magnetic resonance imaging (MRI) is the modality of choice for evaluation of TMJ disc position, it is sometimes difficult to determine when it is displaced or reduced. The MR images of 273 Patients with a clinical diagnosis of TMJ disorders were assessed for disc position and configuration. Most (90-97%) of the slightly anteriorly displaced discs were reduced to the normal position in the open-mouth position. However, the greater part (76%) of the distorted discs was completely displaced anteriorly and without reduction. Since no distorted discs were found in the normal disc position, we conclude that discs are distorted after displacement.