Effects of compressive forces on proliferation and matrix synthesis in mandibular condylar cartilage of the rat in vitro.

The cartilage from 4-day-old rats were exposed to continuous and intermittent compressive forces. Proliferative activity and matrix synthesis in vitro were determined by measuring the incorporation of [3H]-thymidine, [35S]-sulphate and [3H]-proline by autoradiography and liquid-scintillation counting. The findings suggest that a continuously-applied force of approx. 0.5 g stimulated proliferation in the condylar cartilage but reduced the synthesis of the sulphated glycosaminoglycans and collagen. A stimulatory influence on the synthesis of these matrix components, on the other hand, was observed when the condylar cartilage was exposed to an intermittent force (0.7 Hz) of approx. 0.5-1.0 g; this intermittent force, however, reduced the proliferative activity. It appears that, at least in vitro, the basic growth processes in the condylar cartilage can be regulated by compressive forces.