[Observation of Carabelli's trait on permanent maxillary molars]

To investigate the prevalence of the Carabelli's trait in a Chinese population.

Direct intraoral examination was conducted on 2758 Han Chinese people. The expression of Carabelli's trait was divided into 5 grades. Software SPSS 13.0 software package was used for statistical analysis. The trait frequency differences between two genders, between right and left sides were evaluated using Chi-square tests. Correlations in the presence of the trait between bilateral antimeric teeth and between first and second molars at the same side were determined by Kendall test.

The trait frequency was 36.18% (40.73% of the males and 32.13% of females) for the first and 1.39% (1.82% in males and 0.99% in females) for the second molars by individual counting method. Sex difference was statistically significant for the first molars (P<0.01). The bilateral concurrence rate was 72.97% and 48.57% for the first and second molar, and the bilateral correlation coefficient tau was 0.77 and 0.65, respectively. The correlation between the first and second molar in the same teeth district was weak (tau=0.13, P<0.01).

Evaluating the prevalence of Carabelli's trait in Chinese populations by using a standardized method has great anthropological significance.