Streptococcus mutans and Streptococcus dentisani in dental biofilm of children with different caries status: a pilot study

Objective: Streptococcus mutans is one of the etiological agents associated with caries due to its ability tometabolize carbohydrates and resist acidic environments. On the other hand, Streptococcus dentisani, showscharacteristics associated with caries control due to its ability to inhibit growth of cariogenic bacteria. Theaim of this work was to quantify the levels of Streptococcus mutans and Streptococcus dentisani from dentalbiofilm of children related to their caries situation. Material and Methods: After identification of morphologiccharacteristics of reference strains was performed, clinical isolates of biofilm compatible with these strains wereselected and the Polymerase Chain Reaction technique was performed using species-specific primers. Biofilmsamples from 25 children with caries and 21 without caries were collected to quantify the levels of S. mutans andS. dentisani. Results: There were statistically significant differences in the levels of S. mutans in the caries groupand the levels increased as the severity of the carious lesion increased. By contrast, higher levels of S. dentisaniwere found in the caries-free group, although no statistically significant differences were found. In addition,the levels of S. dentisani decreased as the severity of the carious lesion increased. Conclusion: The increasein the frequency of S. dentisani in the caries-free group suggests the possibility of requiring minimum levels ofthis species in the dental biofilm to show an actual protective effect. It must also be considered that this effectmight be related to intrinsic factors in children and the intraspecies genetic variability found in every individual. KEYWORDSBiofilm; Clinical isolates; Dental caries; Streptococcus dentisani; Streptococcus mutans.