Masticatory Function and Malocclusion: A Clinical Perspective

Until fairly recent times, human populations were characterized by worn, well-aligned dentitions. Epidemiological data show that the decrease in dental wear and the increase in malocclusion took place simultaneously with the adoption of a modern lifestyle. There is strong evidence indicating that these changes were caused by a decrease in masticatory-functional demands. As such, the epidemiological findings are not compatible with the evolutionary-genetic explanations. The recent increase in occlusal variation demonstrates the high plasticity of occlusal characteristics and suggests that humans possess a genetic makeup that is sufficient for the development of a normal occlusion, given the correct environmental circumstances. External influences can be considered as tertiary inductors of the genomic processes that are involved in the growth of the craniofacial structures and development of the occlusion. Only those facial structures that are able to react to epigenetic factors, ie, show developmental plasticity, can be influenced by orthodontic therapy. Because the plasticity of each characteristic establishes the limits of therapeutic actions, orthodontic treatment should be based on an understanding of how the genetic and epigenetic factors interact during growth and development.