Quantity of Mutans Streptococci of Mothers and Infantsf Dental Caries

Objectives: Mutans streptococci colonized in an infant was thought to be derived from the mother's oral cavity. The aim of this study was to examine the relationship between quantity of mutans streptococci in mothers and occurrence of dental caries in infants. Materials and Methods: At the age of 2.5 years, 20 infants and their mother were examined about the dental caries prevalence. Plaque sample of infant was collected by swabbing upper lateral teeth surfaces. At the same time, stimulated saliva was collected from mothers. Plaque sample of infant was inoculated to MSB agar plate, and after anaerobic incubation for 48 hours, colony forming unit (CFU) was determined. Salivary sample of the mother was centrifuged and the precipitation was washed twice with PBS. Subsequently, genomic DNA was extracted from the precipitation. Quantitative Polymerase Chain Reaction analyses were performed using the primer sets those were specific for Streptococcus mutans, Streptococcus sobrinus and universal 16S rRNA. At the 4.5 years, the 20 infants received the same examination as at the 2.5 years. Results: Ten infants were colonized with mutans streptococci and remaining infants were not colonized at 2.5 years of age. The quantity of S. mutans of mother was significantly related to mothers' caries experience (ƒÏ= 0.515, p = 0.020). However, there was no association between colonization of mutans streptococci in 2.5-years-aged infants and the quantity of both S. mutans and S. sobrinus in mothers. The occurrence of dental caries during this research period in infants had an inverse correlation with the quantity of S. mutans (ƒÏ= -0.479, p = 0.033) and caries experience of mothers (ƒÏ= -0.572, p = 0.008). Conclusion: These results suggested that quantity of salivary mutans streptococci in mothers did not influence the occurrence of dental caries in the child.