Thickness of the articular soft tissue of the temporal component in temporomandibular joints with and without disk displacement

Objective. The purpose of this investigation was to test the hypothesis tha t temporomandibular joint disk displacement is associated with significant functional adaptive changes of the articular soft tissue of the articular e minence. Study design. Thirteen temporomandibular joint autopsy specimens with norma l superior disk position and 12 with complete anterior disk displacement we re cryosectioned, and sections were stained and photographed. At a magnific ation of x20 the soft tissue was measured (1) at the inflection point, (2) on the posterior slope, (3) at the apex, and (4) on the anterior slope of t he articular eminence. Results. Displacement of a deformed or nondeformed temporomandibular joint disk without perforation of the posterior disk attachment was associated wi th significantly increased thickness of the articulating soft tissue at the apex and on the posterior and anterior slopes of the articulating eminence . When disk displacement was associated with a perforation of the posterior disk attachment, the soft tissue was not significantly thicker than in joi nts with normal superior disk position. Conclusions. Increase in articulating soft tissue thickness is interpreted as an adaptive mechanism to maintain the condyle path and withstand excessi ve loading at interposition of the temporomandibular joint components. When the plasticity of the tissues is surpassed, the adaptation will be thwarte d and replaced by tissue breakdown.