Genetic Parameters of Dentofacial Development

¹ Department of Preventive Medicine and Genetics, Bowman Gray School of Medicine, Winston-Salem, North Carolina

We have seen from the study of twins, pedigrees, and populations ample evidence to support the generalization that genetic factors participate in every aspect of dentofacial development. On the other hand, it is also evident that our knowledge has greater breadth than depth. Though we are best prepared technically and methodologically for the study of discontinuous inheritance, we have seen that few genes have been identified for which we have adequate genetic documentation. Beyond the identification of such genes, we know little or nothing regarding their mutation rates, linkage relationships, or biochemical basis. Hence one cannot help but agree with Lasker's statement, "I think that it is fair to say that genetic studies of the teeth have not kept abreast of racial studies of the teeth."³⁶ Since it is genetic variability which is of evolutionary significance, one can appreciate the limitations placed on inferences regarding evolutionary changes and racial differences by our uncertainties in identifying genetic variability.

The study of continuous variability is especially difficult in man, as the review of preceding studies has suggested. The greatest contributions have come from twin studies. However, newer statistical techniques and the advent of the computer permit the construction and test of hypotheses which would have been formidable if not impossible in the past. Though environmental effects are generally confounded with genetic effects in studies of family groups, the study of foster children and twins permits partition and estimation of their relative contributions to variability.

Whether one considers continuous or discontinuous genetic variability, it seems apparent that we are but a small distance on the way to a complete understanding of the genetic parameters of dentofacial development. Additional studies with more rigorous methods are needed. Further, suggestions that some traits are regulated primarily by genetic factors are based on tenuous grounds and could be profitably re-examined using newer methods. On the other hand, summation of our present knowledge convinces us that genetic factors cannot be ignored if understanding the process of dentofacial development is our goal.

This article has been cited by other articles:

				R. H. Biggerstaff Heritability of the Carabelli Cusp in Twins Journal of Dental Research, January 1, 1973; 52(1): 40 - 44. [Abstract] [PDF]

				D.R. Brothwell Some Problems and Objectives Related to the Study of Dental Variation in Human Populations Journal of Dental Research, September 1, 1967; 46(5): 938 - 941. [PDF]