The geographic distribution of caries prevalence rate among 3-year-old children in Iwate prefecture was determined according to political divisions in computing the annual statistical data for 1987. High caries prevalent areas were concentrated in the mountainous regions or the northern part of Iwate prefecture. The relations between these geographic differences in caries prevalence and community characteristics were studied by factor analysis. Three common factors (Factors I, II and III) were selected from a total of 20 community, socio-economical, cultural, and health indices of 62 municipal areas and these were characterized as “industry”, “population” and “medical service, ” respectively. The structural analysis of each municipal community using factor scores corresponding to Factor I or II revealed that the 62 municipal areas in Iwate prefecture could be classified into “urban” and “rural” areas, and the low caries prevalence rate among 3-year-olds was a dominant characteristic of the urban communities. In contrast, rural communities had high caries prevalence, but the low caries prevalent areas were not always coincident with the urban areas.
