POSTERIOR DISC DISPLACEMENT IN THE TEMPOROMANDIBULAR-JOINT

Purpose: The purpose of this study was to describe the imaging charact eristics of posterior disc displacement of the temporomandibular joint (TMJ). Materials and Methods: The study was based on 35 joints with p osterior disc displacement and a control material of bilateral TMJ ima ges of 62 healthy volunteers. The images were analyzed, and criteria f or posterior disc displacement were developed. Results: Posterior disc displacement was characterized by the disc or a major part of the dis c being located posterior to the superior prominence of the condyle. T hree subcategories of posterior disc displacement could be identified: a thin flat disc, a grossly posteriorly displaced disc, and a perfora ted disc with a portion of the disc displaced posteriorly. Posterior d isc displacement was not seen in anp of the asymptomatic volunteers. C onclusion: Posterior disc displacement of the TMJ is rare but has prob ably been overlooked in the past because of a lack of well-defined ima ging characteristics.