The temporomandibular joint in young adults at autopsy: a morphologic classification and evaluation.

Macroscopic features of temporomandibular joints (TMJs) were studied in young adults who comprise the largest portion of individuals seeking TMJ treatment. Deviation in form (DIF), arthrosis, size, shape and disc displacement were evaluated on ninety-five autopsied TMJs. Few TMJs (13%, 12/95) showed no intracapsular changes. Thirty-nine per cent (37/95) of the TMJs displayed mild-to-marked DIF in all three TMJ components. Smaller changes were more prevalent and tended to appear in the younger TMJs. Condylar changes were more exuberant and extensive compared to the other components. Minor arthrotic lesions were visible in 3% (3/95), and all displayed DIF. Disc displacement was found in 12% (11/95) and was more common in women (P greater than 0.05). Folding and deformation of the articular disc was associated with disc displacement (P less than 0.01), the direction of which was mostly anteromedial. Most of the unchanged condyles' components had curved, slightly rounded, convex, and elliptical shapes when viewed from different planes (P less than 0.01). Applied in diagnosis, the presence of DIF can be inferred from features which deviate from the above shapes. The concept that the above macroscopic changes might be a precursor to TMJ arthropathy in susceptible individuals is compatible with the results of this study, but the most apt characterization is that TMJ changes in this age group are adaptive phenomena occurring in order to cope with the details of articular fit and function.