Quantitative Analysis of Streptococcus Mutans, Streptococcus Sobrinus and Streptococcus Sanguinis and their Association with Early Childhood Caries

Introduction: Severe Early Childhood Caries (S-ECC) remains highly prevalent worldwide. Streptococcus mutans and Streptococcus sobrinus are causative pathogens of dental caries and strongly involved in plaque or oral biofilm formation. Streptococcus sanguinis has antagonistic relationship with S. mutans and it might delay the colonisation of S. mutans in the oral cavities. Aim: To quantify S. mutans, S. sobrinus and S. sanguinis between 2 groups {S-ECC and Caries Free (CF)} of Thai children and to analyse the association between these bacteria and caries-related factors. Materials and Methods: Supra-gingival overnight plaque samples were collected from 120 Thai children aged 2-5 years (S-ECC=CF=60) using sterile toothpicks and released in 1 mL of TrisBase and EDTA buffer from January 2015 to December 2017. They were asked to expectorate saliva into a cup, plaque and gingival indices and dmft scores were recorded, parent's demographic and children's oral hygiene care and diet were assessed using questionnaire. DNA extraction and quantitative real-time PCR was performed. Different amounts of each bacterium were analysed by Mann-Whitney U test (p<0.05). The correlation between amounts of each bacterium and other clinical factors were analysed by Spearman's correlation test (p<0.05). Results: The guardian's demographic data, habit of milk bottle and breast feedings, oral hygiene care and consumption of cariogenic snacks were different between the two groups. S.mutans and S.sobrinus in plaque were higher in S-ECC. S.sanguinis in saliva and total bacteria were higher in the CF group. Plaque and gingival indices in S-ECC were higher than in the CF group. S.mutans levels in dental plaque and saliva was not significantly different. Conclusion: S.mutans and S.sobrinus were associated with S-ECC while S.sanguinis was associated with caries-free. Socioeconomics and children's oral hygiene care and diet were important factors associated with S-ECC.