[Forms of eccentric posterior displacement of the articular disc]

The temporomandibular joints of 40 patients with suspected intraarticular soft tissue displacement have been examined clinically and with the aid of electronic recording methods. The disc position has been verified by means of magnetic resonance tomography. The results demonstrate that Farrar's reciprocal clicking noises, interpreted as an anterior displacement of the articular disc, are not pathognomonic for the presence of a centric anterior displacement, but may also be associated with eccentric posterior disc displacement. Non-invasive imaging procedures show them as posterior displacements of the articular disc in eccentric mandibular positions. Eccentric posterior disc dislocation out of the joint space is associated with reciprocal clicking, i.e. an initial or terminal dislocation click during opening and a terminal repositioning click during closure. Centric anterior dislocation, on the other hand, was not found to be associated with terminal joint clicking during opening.