Magnetic resonance imaging evaluation of temporomandibular joint disc deformities in relation to type of disc displacement

Purpose: This study was undertaken to assess the relationship between the temporomandibular joint (TMJ) disc deformity and the type of internal derangement. Patients and Methods: One hundred thirty-three TMJs of 72 patients (53 female and 19 male) with intracapsular dysfunction were studied using clinical and magnetic resonance imaging examinations. Results: Of the 133 TMJ discs, 41.35% had no deformity, whereas 18% of the discs were folded, 19.55% were lengthened, 9.77% were round, 7.51% were biconvex, and 3.75% had thick posterior bands. The frequency of disc deformity was greater with anterior disc displacement without reduction than in cases of anterior disc displacement with reduction (P < .001). Folded and round discs were most common in cases with TMJ anterior disc displacement without reduction (P < .0001). An increase in length was seen in 56.75% of the cases with anterior disc displacement with reduction, whereas 100% of nonreducing discs were mainly folded or rounded. Crepitation was correlated with folded and round disc deformities, whereas lengthening was the feature of reducing discs associated with early and intermediate clicking. Conclusions: The results show that the degenerative changes in the TMJ disc are influenced by the degree and the type of disc displacement. The more advanced the internal derangement, the more deteriorated the disc configuration. (C) 2001 American Association of Oral and Maxillofacial Surgeons.