Risk factors for early colonization of mutans streptococci – a multiple logistic regression analysis in Swedish 1-year-olds

BACKGROUND: Mutans streptococci (MS) are closely related to the development of dental caries and are usually established in the oral cavity during early childhood. The aim of the study was to identify factors associated with the presence of MS in Swedish 1-year-olds. METHODS: Parents completed a questionnaire on different caries-associated factors and an oral bacterial sample was collected from 1,050 (526 boys, 524 girls) 1-year-olds. Multiple logistic regression analyses were performed to identify risk factors for colonization with MS. RESULTS: MS were found in 27% of the 1-year-olds with teeth. High or very high MS scores (2–3) were found in 72 (7%) of the children. MS score was correlated to the number of erupted teeth (p < 0.001). No difference due to gender was found. Multiple logistic regression analysis showed that presence of bacteria was associated with: caries in a sibling, other beverages than water between meals, and more than 8 erupted teeth. High or very high MS scores (2–3) were associated with other beverages than water between meals, and more than 8 erupted teeth. CONCLUSIONS: Number of teeth present, diet and family aspects were factors associated with presence of MS in 1-year-olds. To develop high or very high MS scores, the number of erupted teeth and dietary habits are important.