Effect of Dental Probiotics on Inhibition of Streptococcus mutans

Objectives: Probiotics represent an approach to replace pathogenic microorganisms with non-pathogenic types. The aim of this study was to evaluate the possible inhibitory effects of dental probiotics on the cariogenic bacterium Streptococcus mutans (S.mutans) in high caries risk patients with high or low S.mutans counts at baseline.
Methods: A total of 20 consenting adult patients with high caries risk (according to CAMBRA-protocol) were recruited while not having any complex medical history or recent antibiotic usage (IRB approved). Standardized oral hygiene instructions and oral hygiene care kit were given to all patients after periodontal cleaning. Patients were given one-month supply of dental probiotic tablets containing live bacteria of S.salivarius K12, S.salivarius M18, L.reuteri, L.paracasei and zinc (Hyperbiotics Inc.) following manufacturer’s instruction (1tablet/day, before bed). Upon completion of study (1-month), the subjects were recalled for sampling. Saliva samples were collected at baseline and 1-month recall by chewing a paraffin wax to stimulate salivation. Samples were then diluted to 100, 1000 and 10,000 times in phosphate-buffered saline. Resulting serially-diluted bacterial suspensions were inoculated to a mitis-salivarius-bacitracin-potassium-tellurite agar plate and incubated in an anaerobic jar at 37°C for 48h. S.mutans colonies observed on the agar plate were counted. Results were statistically analyzed using ANOVA with a Tukey post hoc test.
Results: After 1-month treatment with probiotics, patients with either high or low level of S.mutans at baseline showed the reduction of S.mutans at the dilution factors of 100-fold (50.57% reduction, p< 0.001), 1000-fold (65.4% reduction, p=0.03) and 10,000-fold (57.3% reduction, p<0.001).
Conclusions: Daily administration of dental probiotics for one month sufficiently suppressed the level of oral S.mutans. Further long-term research is needed to evaluate the sustainability of probiotics on the continued suppression of this cariogenic bacterium.