Quantitative analysis of salivary and biofilm bacteria associated with cavitated and non-cavitated carious lesions in pre-school children

Abstract

ObjectiveTo quantify and compare Streptococcus mutans (S. mutans) and Lactobacillus fermentum (L. fermentum) in saliva and biofilm of caries-free children to those with cavitated and non-cavitated lesions. DesignOne hundred and thirty-five 3–4 years old children were grouped (n = 45 in each group) according to their caries status:•Caries-free (absence of any clinically detectable non-cavitated and cavitated lesion)•With only non-cavitated lesions (presence of at-least one non-cavitated lesion on any tooth surface but no evidence of cavitated lesion anywhere); and•With cavitated lesions (presence of at least one cavitated carious lesion with or without any other non-cavitated carious lesion anywhere).Clinical examination was done by a calibrated examiner. Biofilm and saliva were collected to quantify the microorganisms using qRT-PCR. The decayed-missing-filled surfaces (dmfs) was calculated by adding the number of decayed (ICDAS-II score 3–6), filled (ICDAS-II score 7 and 8) and missing (ICDAS-II score 9) surfaces due to caries. The correlation between the bacterial amounts and the number of carious surfaces was evaluated using Spearman’s correlation coefficient. The levels and proportions of the microorganisms were compared using the Kruskal-Wallis test at an α-level of 0.05. ResultsThe quantity of S. mutans and L. fermentum was significantly higher in saliva and biofilm of children with cavitated lesions, followed by those with non-cavitated lesions and the lowest in caries-free children. Also, salivary and biofilm S. mutans, along with biofilm L. fermentum levels, significantly correlated with the number of non-cavitated surfaces; while salivary and biofilm S. mutans and L. fermentum levels significantly correlated with the number of cavitated surfaces. Additionally, dmfs scores significantly correlated with the salivary and biofilm S. mutans and L. fermentum levels. ConclusionsS. mutans and L. fermentum in saliva and biofilm samples are associated with caries lesion severity.