Dentofacial Growth

The majority of growth and development that occurs in the head from infancy to adulthood is in the facial area with most of the growth occurring before 8 years of age. Since a major need for orthodontic treatment is created by asymmetrical growth of the jaws, it is necessary to learn how skeletal growth is influenced and controlled to understand some of the causes of malocclusion and dentofacial deformity.

In normal development we grow from the head down or what is known as the "cephalocaudal gradient of growth". After the third month of pregnancy, the baby's head takes up almost 50% of the total body length. The cranium or brain area of the head is large relative to the face and represents more than half the total head size. The limbs are very rudimentary and the trunk or body is largely underdeveloped.

By the time of birth the limbs and trunk have grown at a much faster rate and the head has decreased to about 30% of the entire body length. We continue growing in this pattern resulting in a progressive reduction in head size to body length. The average adult head comprises about 12% of the entire body length. The legs at birth are about one third the entire body length while they average about one half the body length of an adult.

This developmental scheme is no accident when you consider that at birth our very survival depends on our ability to breath and swallow. An airway must be established within a few minutes of birth and must be maintained thereafter. The newborn infant's next physiologic priority is to obtain milk. This is accomplished by suckling and swallowing.

At birth the overall length of the head is approximately 60 to 65% complete. By 7 years of age the head reaches about 90% of it's full size and by 12 years of age the head has usually completed growing. Moving a step further, when comparing proportionally the skull of an infant to that of an adult we find that the infant has a much larger cranium and a much smaller face than the adult. The face comprises the major area of growth in the skull after birth.

It goes without saying that growth is strongly influenced by genetic factors, but we also know that growth is affected by our environment in the form of nutritional status, degree of physical activity, health or illness, and a number of other similar factors.

This is important in dentistry because as dentists we want to help guide this growth and development to the best possible stable tooth relationship within the framework of acceptable facial esthetics. We must also try to make any necessary orthopedic (bony) changes or corrections and eliminate any harmful environmental factors early in life, while growth and development is still taking place.