Comparisons of dental maturity between the rural community of Kuhmo in northeastern Finland and the city of Helsinki.

The aim of the study was to check whether dental maturity charts made in southern Finland can be used without modifications in other parts of the country. For this reason the dental maturity of 90 children living in the sparsely populated areas of Kuhmo in northeastern Finland was compared with that of a larger sample of Helsinki children. Most of the Kuhmo children were 7.0-8.5 and 10.5-12.5 yr of age. The method of Demirjian and associates was used to estimate dental maturity. The means of dental maturity scores were greater in Kuhmo in most half-year groups in both sexes. The median dental maturity scores of Kuhmo children were between the 50th and 84th percentile curves of Helsinki children. A referent of the same age and sex was chosen for each Kuhmo child from the Helsinki children. The paired t-test was based on the difference in dental age. The dental age of the Kuhmo children was higher (P less than 0.05). These findings suggest differences in dental maturity within a fairly homogeneous population, which should be considered when national charts are used.