３歳児歯科健康診査成績の時系列解析 ４． ３歳児歯科保健水準の時系列変化と社会変動の関連性

Abstract

We used factor analysis to study the relation between regional difference in dental caries prevalence rate among Japanese 3-year-olds and 31 prefectural socioeconomical indices such as population, industry, culture and health.In 1975, 1980 and 1985, five common factors clearly represented the prefectural socioeconomical indices and were closely related to the community characteristics. 47 prefectures were divided into three areas such as “rural”, “urban-rural” and “urban” by means of cluster analysis based on factor scores.The most significant factors characterizing urban and rural areas were population and industrial structures during the decade from 1975 to 1985, when gravitaion of the population toward cities and aging of the rural population occurred. In parallel with the increase in difference between urban and rural areas, urban-rural prefectures around big cities have been gradually urbanized. Urban areas, however, had little change and the caries prevalence rate among 3-year-olds was constantly low. On the other hand, constant higher caries prevalence rate in rural areas has been observed.The present investigation indicates that recent declining trends in caries prevalence among 3-year-old Japanese children could due to the decrease of caries prevalence in “urban-rural”prefectures where the social structure was remarkably changed.