Muscle physiology and its implication in orthodontics

A change in muscle function can initiate morphologic variation in the normal configuration of the teeth and supporting bone, or it can enhance an already existing malocclusion. In the latter instance, the inherent structural malrelationship calls for compensatory or adaptive muscle activity to perform the daily functions. The structural abnormality is increased by compensatory muscle activity to the extent that a balance is reached between pattern, environment, and physiology. At times, it is impossible to assign a specific cause-and-effect role to any one factor. It is imperative that the orthodontist appraise muscle activity and that he/she conducts his orthodontic therapy in such a manner that the finished result reflects a balance between the structural changes obtained and the functional forces acting on the teeth and investing tissues at that time.