Relationship between socioeconomic status and dental caries prevalence in 3-year-old Japanese children

Abstract

It has been reported that there are differences in the prevalence of deciduous caries among the different regions of Japan. These differences have been explained by socioeconomic factors in each region. However, there has been no analysis using data from the past decade, even though the socioeconomic situation of these regions has been changing during that time. We investigated the relationship between dental caries prevalence in Japanese 3-year-olds and socioeconomic status in 1995, 2000 and 2005. The data used in this study were collected at the prefectural level. Dental caries maps for 3-year-olds in each prefectures in 1995, 2000 and 2005 were drawn based on the data from annual dental health check-ups. Multiple linear regressions analysis was conducted with the average number of decayed, missing and filled deciduous teeth (dmft) as the dependent variable, and socioeconomic status as the independent variable. The dmft for 3-year-olds decreased between 1995 and 2005, and regional variations in the prevalence of dental caries among the prefectures decreased every year. Multiple linear regression analysis showed that the dmft of 3-year-olds was significantly associated with proportion of workers in the primary sector, the average size of the household, the unemployment rate, and the number of nursery schools per million children under 4 years of age (p<0.05, R^2=0.598). In 2000 the dmft for 3-year-olds significantly correlated with the proportion of workers in the primary sector, the average size of the household, the unemployment rate, and the amount of family savings (p<0.05, R^2=0.712). In 2005 the dmft for 3-year-olds significantly correlated with the amount of family savings, the proportion of household budget spent on education, the proportion of workers in the primary sector, the number of nursery schools per million children under 4 years of age, and the number of dental offices per 100,000 people (p<0.05, R^2=0.706). Factors related to dental caries in 3-year-olds changed from factors relating to industrialization to factors relating to stability of life. The reasons for this change might be explained by changes in life-styles and the reduction in dental caries. In 2005 it was found that factors associated with dental services affected dental caries in 3-year-olds. Our findings suggest that it is necessary to consider socioeconomic status when planning public health policy for dental caries prevention.