Abstract
The aim of this study was to determine regional differences in caries prevalence among 3-year-old children. Caries data on 35,954 3-year-old children, residing in 6 districts of Okayama city between 1998 and 2004, were obtained from the records of public dental health check-ups. Caries prevalence in each district was calculated separately. Multilevel analysis with two levels was applied using the yearly variation as level 1 and spatial variation as level 2. In the fixed part, the slope of caries prevalence according to year was -2.156, indicating a decrease in caries prevalence during the study period. The intercept of the model was 38.656. In the random part, the variances of the intercept and slope in level 2 (spatial variation) were 6.992 and 0.018, respectively, which suggested a spatial variation of caries prevalence in this city. The negative covariance of the intercept and the slope (-0.624) demonstrated that the district with a higher intercept exhibited a greater decline in caries prevalence. It was concluded that changes in caries prevalence among 3-year-old children varied according to district, where the same dental health service is provided equally.
