Clinical implications of a Bolton Index reappraisal: an Italian survey. Anwendung und klinische Neubewertung des Bolton-Index in einer italienischen Probandengruppe"

This study determined the size of individual permanent teeth along with the Bolton ratios in an Italian population and compared the distribution of clinically signifi cant tooth size discrepancy (TSD) according to the Bolton and millimetric methods. Materials and Methods: Data from dental casts of 150 Italian subjects (90 females, mean age 15.9 ± 6.4 years; 60 males 14.5 ± 4.2 years) were recorded. Tooth size discrepancies were calculated considering both Bolton index (mean ± SD) and millimetric discrepancy. Results: Overall and anterior Bolton ratios (as percents) were 91.3 ± 2.0 and 77.9 ± 2.7, respectively. According to the Bolton rule, normal range was set as within the mean ± 2 SD range. The study found that 5.3% and 20.0% in the overall and anterior Bolton ratios, respectively, were out of such normality. However, greater frequencies of 52.6% and 21.4% in the overall and anterior millimetric discrepancies, respectively, were above the 1.5 mm. Merging overall and anterior millimetric discrepancies, up to 56.7% of the sample presented a value larger than or equal to 1.5 mm. No differences between the sexes were detected. Conclusions: The present study has showed signifi cant differences in the degree of TSD interpretation between Bolton Index rules and absolute millimetric discrepancy. The rule of the 2 SD range was not able to detect all the clinically relevant TSD. An underestimation of the TSD by using the current Bolton Index rule could lead to unsatisfactory fi nishing of the orthodontic treatment.