The effect of gradual distraction of the mandible on the sheep temporomandibular joint.

The effect of gradual distraction of the mandibular ramus on the condylar process of the temporomandibular joint (TMJ) was studied in 17 growing sheep. Gradual lengthening affected both operated and contralateral sides. An enhancement of the endochondral ossification was noticed with marked osteoblastic activity between the cartilaginous layer and the bone formed. The cartilage was thinner and the bone structure more dense than in nonoperated controls, and woven bone predominated. These changes seemed to be partly reversible in the long term.