Theories of Craniofacial Growth in the Postgenomic Era

The controversies surrounding the use of dentofacial orthopedics to correct a developing maxillomandibular discrepancy—ie, growth modification—have been based to a large extent on evolving concepts concerning the biological mechanisms of craniofacial development and growth. At the start, these concepts were based on naive assumptions about the perceived competing roles of heredity and the environment, often framed within the context of the age-old “nature-nurture” controversy. Moreover, orthodontists and craniofacial biologists alike tended to believe that there was a single, overriding mechanism governing the growth of the craniofacial skeleton. As a result, much of the orthodontic research on the growth of the face and jaws tended to focus on a search for what might be called the “Holy Grail of Craniofacial Biology”: a single theory of craniofacial growth that is both biologically accurate and clinically effective. This article traces the development of competing concepts and theories of craniofacial development and growth and relates those theories to concomitant developments in the field of genetics. The overall conclusion is that orthodontics is well-positioned to enter a new era through the incorporation of the principles of developmental-molecular genetics into the treatment of developing malocclusion and growth-related jaw discrepancies.