Primate experiments in malocclusion and bone induction.

It has been recognized for many years that muscle function influences bone formation and morphology. It is hypothesized here that the movement of bone into new positions within a muscle system results in rearrangement of the stress distribution and reorganization of shape and internal structure. To test the above hypothesis, clinical and animal experiments involving the use of posterior occlusal bite blocks, Herbst appliances, and temporal and masseter muscle stimulation were undertaken. Chronic or continuous alteration in mandibular position within the neuromuscular environment with the posterior occlusal bite block and the Herbst appliance in a sample of monkeys produced extensive condylar remodeling and change in mandibular size. Short periods of induced hyperactivity in the masseter and temporal muscles were associated with the production of malocclusion symptoms. Excess induced temporal muscle activity of specific frequency and intensity may interfere with the remodeling of bone grafts placed under the temporal muscle, while a lesser level of activity was associated with bone remodeling.