Genetic analysis of deciduous tooth size in Australian twins

Investigations of permanent dental crown size in twins and family groups in dicate a high degree of transmissible control, but little is known about th e relative contributions of genetic and environmental factors to variation in size of the deciduous (primary) teeth. Here, maximum mesiodistal and buc colingual crown dimensions of maxillary and mandibular primary teeth were m easured from dental models of 602 individuals, including 99 monozygous (MZ) twin pairs, 81 dizygous (DZ) same-sex pairs, 41 DZ opposite-sex pairs, and 160 singletons. Data were subjected to univariate genetic analysis with th e structural-equation-modelling package, Mr using the normal assumptions of the twin model. A model incorporating additive genetic (A) and unique envi ronmental (E) variation was found to be the most parsimonious for all tooth -size variables. Estimates of heritability for deciduous crown size ranged from 0.62 to 0.91. This study shows that variation in deciduous crown size has a strong genetic component, similar to that observed in the permanent d entition. Further studies are required to determine whether the underlying genetic mechanisms are the same for both deciduous and permanent teeth. (C) 2000 Elsevier Science Ltd. All rights reserved.