Salivary Streptococcus mutans and caries prevalence in Brazilian schoolchildren

Comparative Analysis of the Microbial Profiles in Supragingival Plaque Samples Obtained From Twins With Discordant Caries Phenotypes and Their Mothers

Early childhood caries (ECC), the most frequent disease of oral cavity in preschool children, is the consequence of microbial, genetic, biochemical, socioeconomic, physical, environmental and health-influencing behavioral factors. To investigate the role of the oral microbiome and the impact of host and environmental factors in the occurrence and development of ECC, we studied the supragingival plaques of 14 twin pairs and a set of triplets with discordant caries phenotypes and 15 mothers, applying the Human Oral Microbe Identification using Next Generation Sequencing technique (HOMINGS). A total of 2,293,650 reads revealed 11 phyla, 116 genera, and 139 species of micromiome. Comparative analysis between the caries and caries-free group at species level revealed that the relative abundance of Streptococcus mutans, Lactobacillus fermentum, Actinomyces islaelii, Neisseria sica, and Veilonella dispar was much higher in caries group (P < 0.0001). Furthermore, monozygotic twins exhibited a higher degree of similarity than dizygotic twins. Finally, we analyzed the relationship between environmental factors and the oral microbiome, and our results indicat that the frequency of taking sweet food is associated with ECC. We conclude the following. First, the occurrence of Streptococcus mutans, Lactobacillus fermentum, Neisseria sica, and Veilonella dispar is strongly associated with the occurrence of ECC. Second, host genetic factors influence the oral microbiome composition, while environmental and behavioral factors like the frequency of taking sweet foods have an impact on the distribution of caries-related bacteria.

Restoration-related salivary Streptococcus mutans level: a dental caries risk factor?

OBJECTIVES

The salivary level of Streptococcus mutans related to filled teeth was compared with the levels related to decayed and sound teeth, in order to establish whether the presence of restorations may increase the risk of infection of other teeth by Streptococcus mutans.

METHODS

The sound, decayed and filled teeth were recorded in 809, 6-7-year-old school-children. Salivary Streptococcus mutans detection (i.e. more than 1 x 10(4) CFU/ml) and counts were evaluated. Streptococcus mutans log count means and prevalence values of subjects with only sound teeth (group 1), with filled, without decayed teeth (group 2), with decayed, without filled teeth (group 3), were calculated and compared using the Student's t-test and the chi-square test. The effect of filled, decayed and sound teeth on Streptococcus mutans level was also evaluated using logistic regression.

RESULTS

Log count means and prevalence values of group 2 subjects were significantly lower than values of group 3 subjects (means, 0.92 vs 1.66: prevalence, 73.17% vs 94.63%) and statistically not-different from values of group 1 subjects (mean. 0.75: prevalence, 70.06%). The logistic regression analysis showed that the factors significantly increasing the risk of Streptococcus mutans being detected in saliva were only primary and/or permanent decayed teeth. The risk of Streptococcus mutans being detected in saliva was not affected by filled teeth more than sound teeth.

CONCLUSIONS

In the present study population, the salivary Streptococcus mutans level attributable to filled teeth was low; this suggests that treatment of a carious lesion would cause a lowering of Streptococcus mutans concentration to the same levels as those shown by healthy subjects, thus reducing the risk of infection to other teeth.

Oral health in adolescents from a small French town

In France, caries are more prevalent in rural areas than in large cities. This study analyzed the relationship between number of oral health indices and some known risk factors (toothbrushing, sugar consumption, saliva components) and sociodemographic factors in adolescents from a small town. The sample included 112 children aged 12-14 in the north-east of France. School marks was found to be better linked with dental caries indices than the socio-occupational category of parents: gingival index (GI), DMFS, DMFT and caries severity (CS) significantly increased with decreasing school marks; oral plaque was related to socio-occupational of parents. The analysis using the regression method showed that the variance explained by the various factors studied was modest (between 23 and 30%) for GI, initial caries sites (IS), DS, DMFS, DMFT and CS, and was small for plaque (5%) and calculus (3%). This would be due in part to the wide dispersion of these indices. The sex had a non-significant regression coefficient for all oral health indices investigated. For GI, only mutans streptococci (MS) and plaque had a significant regression coefficient. Calculus was explained by any factor considered. Only MS had a significant part in plaque. IS was explained by MS, toothbrushing and age. For DS, only toothbrushing, MS and sweet drinks during meals had a significant part. DMFS and DMFT were explained only by MS and age. CS was explained by MS, age, salivary buffer pH, salivary flow rate, and toothbrushing.