Double mating: its use to study heritable factors in dental caries

When Osborne-Mendel female rats (white) were mated with both an Osborne-Mendel and an NIH Black rat male during the same breeding period, litters were born which contained both Osborne-Mendel (white) and crossbred (grey to black) offspring. The Osborne-Mendel and crossbred animals developed widely different levels of caries activity even though they were exposed to identical environmental conditions during the intrauterine, preweaning, and experimental periods. These findings are indicative of a strong heritable influence on the development of dental caries.