Association between untreated caries and cariogenic bacteria in adolescents in Taiwan

There is a paucity of research focused on salivary bacteria analyzed through real-time polymerase chain reaction (qPCR) among adolescents. The current study determined the quantity of Streptococcus mutans (SM) and Lactobacillus (LB) in saliva obtained from Taiwanese adolescents and investigated the association between the oral bacteria and untreated dental caries.

This cross-sectional study recruited Taiwanese students aged 10-18. Saliva was collected using a Salivette kit and then analyzed through qPCR. The relative quantification values of SM and LB were coded based on mean fold ratios, with values > 2 coded as high and other values coded as low. Untreated dental caries was assessed through standard oral examinations. Univariate and multivariate logistic regression models were used to estimate the association between the levels of bacteria in the saliva of the study participants and the presence of untreated caries.

The study involved 421 adolescents. 56 (13.3%) had both SM and LB values of >2 and were coded as having high levels of bacteria, whereas the other 365 (86.7%) students were coded as having low levels. The multivariate logistic regression analysis revealed that adolescents who had high combined salivary SM and LB levels had an odds ratio of having untreated dental caries of 2.05 (95% CI = 1.09, 3.86, P = 0.027) compared with those who had low salivary SM and LB levels.

The results of the present study indicate that salivary SM and LB levels are significantly associated with adolescents having untreated caries.