An analysis of the Carabelli trait in the mixed deciduous and permanent human dentition.

Permanent first and deciduous second maxillary molars were examined on dental casts of 240 persons. A high degree of equivalence of Carabelli-trait expression between deciduous and permanent molars was demonstrated using the Wilcoxon matched-pairs signed-rank test and chi-square tests. Kolmogorov-Smirnov two-sample tests confirmed a lack of sex dimorphism of trait incidence and expression in permanent and deciduous molars. It is hypothesized that the high degree of within-individual equivalence suggests a low epigenetic and high genetic influence on Carabelli-trait expression and that the findings support the clonal rather than the field theory of tooth morphogenesis.