Effect of compressive forces on phosphatase activity in mandibular condylar cartilage of the rat in vitro.

Intermittent and continuous compressive forces were applied to mandibular condylar cartilages from four days old rats during culture. The distribution and the relative activity of alkaline and acid phosphatase were determined after various periods in culture. The application of a continuous compressive force reduced the activity evenly of both phosphatases in all zones of the condylar cartilage. A small intermittent compressive force (0.5-1.0 g) induced an increase in the intra- and extracellular alkaline phosphatase activity in the entire hypertrophic zone. It is concluded that biomechanical forces can influence the onset of the mineralisation process in mandibular condylar cartilage.