Genetic, Nutritional, and Maturational Correlates of Dental Development

¹ Fels Research Institute, Yellow Springs, Ohio

Considering the variables of (a) tooth size, (b) calcification rate, and (c) movement timing, studied in true longitudinal and family-line context, the largest proportion of variance appears to be genetically determined, with little more than 10 per cent of variance presently attributable to caloric status or protein adequacy per se.

Besides evidence derived from twin studies and sibling comparisons for genetic determination of tooth size, calcification, and movement, higher sister-sister correlations for all three variables suggest X-linked inheritance.

The fact that intra-individual correlations are systematically higher in girls may be attributed to reduplication of the X chromosome, as also appears to be true for ossification timing of individual postnatal hand and foot centers.

However, the large sex difference in canine size evidenced within sibships (7-8 per cent) points to a dimorphism that is possibly influenced by the Y chromosome.

Though nutritional status is only slightly related to tooth-formation timing in the Fels population, larger correlations may be expected where the nutritional range is large, particularly where high-quality protein is a limiting nutrient.

Correlations between maturational status and tooth formation and movement timing are in the expected direction, though low, rising to moderate levels of r at the time of puberty, suggesting direct influence of steroidal hormones on tooth movement of P₂ and M₂.

Particular problems of interest include occasionally large divergences between monozygotic twins, suggesting prenatal influences, and the specific effect of steroids of gonadal and adrenal origin on root formation and tooth movement.

Suggestions for future research include the nutritional extremes, treated panhypopituitary dwarfs, and (considering the metabolic and immunochemical peculiarities now known to exist in the XO and XXY) cases of ovarian agenesis with a normal sex chromatin complement.

This article has been cited by other articles:

				T.E. Hughes, M.R. Bockmann, K. Seow, T. Gotjamanos, N. Gully, L.C. Richards, and G.C. Townsend Strong Genetic Control of Emergence of Human Primary Incisors J. Dent. Res., December 1, 2007; 86(12): 1160 - 1165. [Abstract] [Full Text] [PDF]