Tooth size discrepancies among four ethnic groups

The purpose of this study was to evaluate tooth size ratios in African Americans, Asians, Caucasians, and Hispanics. Mesiodistal widths of the permanent dentition and thickness of the maxillary incisors were measured from pre-orthodontic study models. No significant differences among the populations in the anterior ratio were found. The overall tooth size ratio for African Americans was significantly larger than that of Asians and Hispanics. The frequency of cases with greater than 2 SD of tooth size discrepancy was not significantly different among ethnic groups or sexes. Significant differences were found in maxillary incisor thickness between Asian and Hispanic groups and African American and Caucasian groups. Thickness did not significantly affect the anterior ratio. We conclude that Bolton's anterior ratio can be confidently applied to all four ethnic groups, but Bolton's overall ratio must be used with caution in African Americans.