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 that temporomandibular joint disk displacement is associated with significant functional adaptive changes of the articular soft tissue of the articular eminence.

STUDY

DESIGN

Thirteen temporomandibular joint autopsy specimens with normal superior disk position and 12 with complete anterior disk displacement were cryosectioned, and sections were stained and photographed. At a magnification 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 the articular eminence.

RESULTS

Displacement of a deformed or nondeformed temporomandibular joint disk without perforation of the posterior disk attachment was associated with 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 joints 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 excessive loading at interposition of the temporomandibular joint components. When the plasticity of the tissues is surpassed, the adaptation will be thwarted and replaced by tissue breakdown.