Association between maternal blood lead levels and prevalence of dental caries in the primary dentition of children.

BACKGROUND: Dental caries is a chronic childhood disease and one of the most prevalent public health problems worldwide. Lead is a heavy metal that is taken up by the teeth and bones. However, the association between lead exposure during pregnancy, when the tooth germs are formed, and the prevalence of dental caries in the primary dentition remains unclear. This study aimed to examine the association between maternal blood lead levels and the prevalence of dental caries in the primary dentition of children. METHODS: This cross-sectional study was conducted as an Adjunct Study to the Japan Environment and Children's Study (JECS), which is an ongoing nationwide birth-cohort study. Among children participating in the JECS at the University of Occupational and Environmental Health Sub-Regional Center, those aged 7-8 years underwent oral examination and questionnaire administration. The dft (i.e., sum of the number of decayed and filled primary teeth) was then determined. The dft numerically expresses the dental caries prevalence in the primary dentition (larger value indicates more prevalent dental caries). Poisson regression analyses with robust standard errors were performed to evaluate the association between maternal blood lead levels during pregnancy, measured using frozen samples, and the dft. RESULTS: The study included 139 children, of whom 54.7% were girls, and 89.2% were 7 years old. The median maternal blood lead level was 6.1 ng/g (25-75 percentile, 5.0-7.3). The median dft was 0 (25-75 percentile, 0-4). After adjusting for covariates including age, sex, and oral health status and behavior, maternal blood lead levels were significantly associated with increased dft (prevalence ratio, 1.6; 95% confidence interval, 1.3-1.8; per one standard deviation increase in natural log-transformed maternal blood lead levels). CONCLUSIONS: This study found an association between maternal blood lead levels and the prevalence of dental caries in the primary dentition of children aged 7-8 years. Maternal exposure to lead during mid- to late-term pregnancy may affect the caries susceptibility of children after birth.