Abstract: The aim of this study is to investigate sociobehavioral risk factors from the
prenatal period until 36 months of age, and the caries increment from 24 to 36 months of
the child in Thailand. The data utilized in this study come from the prospective cohort
study of Thai children (PCTC) from prenatal to 36 months of the child in Mueang Nan
district, Northern Thailand. The total sample size recruited was 783 infants. The sample
size with dental caries data was 603 and 597, at 24 months and at 36 months, respectively.
The sample size of having two assessment points with a dental examination (at 24 months
and at 36 months) was 597. Results indicate that the caries increment was 52.9%,
meaning from 365 caries free children at 24 months 193 had developed dental caries at