Microbiology in toothbrush samples from children exposed to lead in southern Thailand

Abstract

Objective. The purpose of this study was to evaluate the prevalence and level of selected oral bacterial species in association with dental caries in low versus high blood lead (PbB) children. Material and methods. With an observational cross-sectional design, a sample of 292 children aged 6–11 years from two primary schools around a shipyard, known to be an area contaminated with lead, were examined. The number of decayed and filled surfaces on deciduous teeth (dfs) and the number of decayed, missing, and filled surfaces on permanent teeth (DMFS) were recorded. Microbiological plaque samples were taken from each child with a toothbrush. Enumeration of 17 bacterial species was carried out using the checkerboard DNA-DNA hybridization technique. Results. Overall means (SD) of dfs and DMFS were 13.2 (9.5) and 1.3 (2.3), respectively. Prevalence of excessive count (≥10⁶ cells/sample) was 100% for 4 known cariogenic bacteria and over 95% in another 2 species. With Bonferroni correction for type I error adjustment, there was no significant association between the count of each bacterial species and PbB and caries experience. The checkerboard method is sensitive in bacteria detection, but may not be suitable for differentiating caries risk in the endemic population.