Streptococcus dentisani and Streptococcus mutans in dental biofilm of preschoolers with and without early childhood caries: a cross-sectional study

Aim: To quantify Streptococcus dentisani and Streptococcus mutans in the dental biofilms of preschoolers with and without early childhood caries (ECC) and to assess their relationships with ECC-associated factors. Methods: A cross-sectional study involving 204 dental biofilm samples from children aged 3 to 5 years was conducted. ECC was diagnosed according to the International Caries Detection and Assessment System (ICDAS II) criteria. DNA was extracted from the dental biofilm samples, and S. dentisani and S. mutans were quantified via quantitative polymerase chain reaction (qPCR). Additional data were collected on oral hygiene status, salivary pH, cariogenic diet, and oral hygiene habits. Multivariate linear regression was employed to evaluate the relationships between ECC and the concentrations of S. dentisani and S. mutans (expressed in CFU/ng DNA), adjusting for confounding variables. Results: The mean concentration of S. dentisani in children with ECC was 0.52 log₁₀ CFU/ng DNA lower than that in caries-free children after adjustment for confounders. Frequent consumption of sweets was associated with a 0.65 log₁₀ CFU/ng DNA reduction in S. dentisani levels. Conversely, children with poor oral hygiene had significantly higher concentrations of S. mutans (2.39 log₁₀ CFU/ng DNA). Conclusion: S. dentisani was more abundant in the caries-free biofilm dental samples of children, whereas S. mutans predominated in those with ECC. These findings indicate that both bacteria may play a role in distinguishing between oral health and disease.