TAURODONTISM IN TWINS WITH CLEFT-LIP AND OR PALATE/

The aims of this study were to determine the frequency of taurodontism of the first and second permanent molars in twins discordant or conco rdant for clefts, the frequency for each type of cleft in twins, and t he concordance-discordance ratio in mono- and dizygotic twins, Thirty- nine pairs of twins (13 monozygotic, 26 dizygotic) between the ages of 7 and 23 yrs were investigated. Taurodontism and hypodontia were dete rmined from orthopantomograms of the dentition. Of the 39 pairs of twi ns investigated, 16 (41%) had taurodontism, equally in mono- and dizyg otic pairs. The highest frequency of the trait was noted in subjects w ith isolated cleft palate and the lowest in cleft lip subjects, Four o f 13 monozygotic pairs with taurodontism were concordant for the trait , as were 9 of 12 dizygotic pairs, Taurodontism was symmetric in 91% o f the affected molar pairs. Concomitant taurodontism and hypodontia wa s observed in 8 of 16 taurodontic twin pairs. We conclude that the eti ology of clefting in our group of twins seems to have an effect on the frequency of taurodontism. A high concordance for taurodontism and a high symmetry of the trait may indicate a strong genetic etiology of t aurodontism.