Sibling similarities in the tempo of human tooth mineralization.

The extent of tooth mineralization is a useful estimate of a child's physiological age it reflects the rate at which the child is developing towards maturity. As it is not known to what degree dental age is regulated by the genotype, this investigation estimated familial resemblance in the tempo of tooth mineralization. Panoramic radiographs of the children in 185 sibships were scored for stages of tooth formation, and dental age was calculated from sex-specific standards. Intraclass correlations of mineralization tempo were computed for maxillary and mandibular canines, premolars, second molars, and third molars. Correlations of mineralization tempo were significantly different than zero for all 10 teeth and ranged from 0.17 (SE = 0.06) for the mandibular second molar to 0.43 (SE = 0.05) for the mandibular second premolar. Intraclass correlations increased significantly when multiple teeth were used to more comprehensively define each child's dental age. Using an unweighted average of all 10 tooth types yielded a correlation of 0.41 (SE = 0.05). It appears, then, that a considerable proportion of the total variability in tooth-mineralization rate can be attributed to transmissible effects operating in the population under investigation.