The effects of immobilization on the primate temporomandibular joint: a histologic and histochemical study

The effects of prolonged immobilization on the primate temporomandibular joint (TMJ) condylar cartilage are reported. After eight weeks of immobilization, changes were assayed histochemically using the specific glycosaminoglycan (GAG) stain safranin O. Following the immobilization period, the articulating cartilage showed marked thinning, disorganization, and loss of the superficial GAG stain. After two weeks of remobilization, further thinning had occurred and GAG staining was nearly absent. Sections from condyles of animals sacrificed serially from two weeks to eight months after immobilization showed a gradual return to the thickness and GAG content of the control animals' condyles. But even at this stage, GAG staining was less marked than in the controls, and zonal reorganization was incomplete. These results suggest that TMJ immobilization is not wholly benign procedure.