Magnetic resonance of the temporomandibular joint: experience at an Italian university center.

Aim: The aim of this investigation was to suggest criteria in order to evaluate magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ). Such criteria have been discussed on the basis of our experience at the Section of Prosthetic Dentistry, Department of Neurosciences, University of Pisa.

Methods: The study sample was constituted by 135 patients. All subjects underwent bilateral MRI of the TMJs to evaluate disc structure and position, bony structure abnormalities, joint effusion localization and entity.

Results: MRI allowed depiction of the articular disc in 98.9% of the TMJs, showing a normal disc structure in 91.1% of the cases and abnormal in 7.7%. The disc-condyle relationship was normal in 46.6% TMJs, while a disc displacement with reduction was revealed in 35.5% cases, a disc displacement without reduction in 16.7% and a posterior disc displacement in 1.5% joints. In the coronal images, the disc was positioned lateral to the condyle in 8.9% of the TMJs and medial in 6.7%. Osseous abnormalities have been found in 177 joints (65.5%), with cases of bony flattening (condyle and/or tuberculum), erosions, subchondral cysts, osteophytosis and sclerosis. T2 sequences showed effusion in 26.7% of the TMJs.

Conclusions: These findings suggest that standardized methodology application and well-defined criteria can facilitate MR imaging observations and interpretation as well as the diagnosis of intra-articular pathologies.