Functional determinants of craniofacial size and shape.

Much of the orthodontic treatment undertaken throughout the world, and particularly in the United States, is aimed at correcting dentoalveolar and skeletal malrelationships. With the current level of fixed appliance refinement, we have become quite adept at achieving excellent occlusions. However we often do not consider one important fact when designing our treatment regime: the craniofacial complex maintains a state of homeostasis regardless of whether structural balance or imbalance exists. Abnormal skeletal or dentoalveolar configurations are counterbalanced by abnormal or atypical patterns of masticatory and perioral muscle function and by pressures of the other associated soft tissue. Therefore, any given overall form-function relationship is stable, even though each of its individual components may have an abnormal configuration or pattern of activity. This stability is demonstrated by the relative consistency of the overall skeletal and dentoalveolar relationships during the growth period; i.e., barring environmental insult or therapeutic intervention, the individual in late adolescence generally resembles himself as he appeared many years earlier.