A three-dimensional analysis of the perceived proportions of maxillary anterior teeth

The proportions of the anterior dentition, which is important for excellent esthetics, have been extensively studied, but there have been no 3-dimensional interpretations. This study was conducted to compare real tooth sizes and perceived tooth sizes between different genders and populations and to analyze the effects of 3-dimensional tooth position and alignment.

Complete dental stone casts were prepared for a total of 139 subjects (50 males and 44 females from Korea and 46 females from Japan). Using 3-dimensional scanning and reconstructions, virtual models were constructed and the widths, lengths and rotations of maxillary anterior teeth were measured. Parameters related to the arch form were measured orthographically. Descriptive statistics and ANOVA were performed to determine the differences among the three groups. A regression model was created to interpret the values of 2-dimensional perceived widths with 3-dimensional measurements and other parameters.

This study observed differences in the average mesiodistal perceived and real dimensions of the maxillary central incisors between Japanese and Korean females, as well as differences in lateral incisor/central incisor ratios and canine/lateral incisor ratios in the perceived 2-dimensional measurements. There were no differences in individual tooth rotations between groups. The r(2) values of the regression model decreased from the central incisors to the canine.

Several differences were found between Japanese and Korean females and the regression models that used real dimensions, rotations and arch form parameters as independent factors were not sufficient to explain the perceived widths of anterior teeth in the study samples.