Correlation of streptococcus mutans and streptococcus sobrinus colonization with and without caries experience in preschool children

Abstract

Background and objectives: The aciduric mutans streptococci (MS) group, including Streptococcus mutans (SM) and Streptococcus sobrinus (SS), is highly cariogenic. Relationship between increments in dental caries and the presence of these species is not yet clarified. It is of great importance to separately determine the presence of these two species for understanding their role in dental caries, accurate prediction, and effective prevention. Hence, this study was undertaken to detect the presence of SM and SS in plaque samples of caries-free (CF), early childhood caries (ECC), and severe early childhood caries (S-ECC) and also to compare the possible relationship between these species with the occurrence of ECC.

Materials and method: In all, 120 healthy children between 3 and 6 years of age were randomly allocated into three groups: Group A (n = 40) CF, Group B (n = 40) ECC, and Group C (n = 40) S-ECC. Plaque samples were collected from all approximal surface and gingivobuccal surfaces of teeth using a sterile universal scaler and dmft/dmfs scores were taken. The presence of SM and SS was evaluated using real-time polymerase chain reaction.

Results: The presence of SM in CF, ECC, and S-ECC was 10.0%, 27.5%, and 42.5%, respectively, and SS was 5.0%, 40.0%, and 47.5% in CF, ECC, and S-ECC, respectively. Comparison of mean relative quantification (RQ) values of SM between three study groups showed significant results between CF and S-ECC at P value 0.003. Comparison of mean RQ values of SS showed significant results between CF to ECC and CF to S-ECC at P value <0.001. This study showed significant results between the mean dmft/dmfs scores in three study groups and the presence of high levels of SM and SS in ECC and S-ECC groups. However, the study showed weak positive correlation between dmfs scores and both SM and SS species in ECC and S-ECC.

Interpretations and conclusion: Higher levels of SS were more closely related to the caries-active lesions leading to severity of dental disease, that is, both in ECC and S-ECC. There was significant difference between mean dmft/dmfs scores in three study groups and it also showed positive correlation between dmfs scores and SM and SS colonization in ECC and S-ECC status.

Keywords: Caries experience; Streptococcus mutans; Streptococcus sobrinus; dental plaque; preschool children; real-time PCR.