Palatally displaced canine anomaly in monozygotic twins.

The palatally displaced canine (PDC) anomaly is a tooth malposition occurring in 1% to 3% of most populations. From the results of family studies, the PDC phenotype appears to be under strong genetic influence. In this study we report monozygotic (MZ) twin girls with bilateral PDC expression. The finding of PDC anomaly in MZ twins--to our knowledge, the first such published case--lends further support to evidence of genetic control of the PDC anomaly.