Standardizing interarch tooth-size harmony in a Syrian population

The Bolton analysis is considered to be a good indicator for evaluating the degree of intermaxillary tooth-size harmony, but the possibility of ethnic variation of these values should be examined. Thus, the aim of this study was to calculate both the anterior and overall ratios of mandibular and maxillary tooth sizes for a Syrian sample of harmonious permanent dentitions and to compare these ratios with the data from the Bolton and the Michigan studies. In plaster models of 55 Syrian patients (11-22 years) with neutral occlusion (Angle Class I), harmonious overjet and overbite, no reduction of mesiodistal tooth width or missing teeth, the mesiodistal widths of each tooth from the incisors to the first permanent molars were measured in both arches. In the statistical data analysis, the anterior and overall ratios were calculated according to Bolton. The results for the anterior ratio (78.99 +/- 2.18) and the overall ratio (92.26 +/- 2.06) showed no statistically significant differences by sex (P > .48). These values and the degree of variation were similar to the original data by Bolton. Both studies differed considerably from the values of the anterior ratio found in the Michigan University study, which also shows a higher degree of variability. Nevertheless, the overall ratios of all three studies were very similar. Therefore, the interarch tooth-size analysis and values for a harmonious dentition developed by Bolton can also be transferred to an Arabian or at least a Syrian population.