Probiotic Bifidobacterium animalis subsp. lactis BL-11 attenuates dental caries development in a Streptococcus...

Dental caries remains the most prevalent oral disease globally, driven primarily by Streptococcus mutans (S. mutans)-mediated acid production and biofilm formation. While fluoride-based strategies effectively promote remineralization, they have limited capacity to restore microbial homeostasis within dental biofilms. Probiotics represent an emerging complementary approach targeting the ecological basis of caries, yet direct in vivo evidence for Bifidobacterium animalis subsp. lactis BL-11 in caries prevention is lacking. This controlled animal study evaluated the anti-caries potential of BL-11 using an S. mutans-induced rat caries model. Eighteen Sprague-Dawley rats were randomly allocated to negative control, model control, and BL-11 intervention groups. The BL-11 group received twice-daily topical application and gavage of BL-11 suspension for five weeks alongside cariogenic challenge. Compared with model controls, BL-11 intervention reduced total Keyes caries scores by 45%, with dentin lesion scores decreased by up to 73%. S. mutans colonization was reduced by 70.3% and lactic acid production by 58.6%. Enamel microhardness and calcium content were significantly preserved. Semi-quantitative histological scoring confirmed markedly reduced dentin demineralization and collagen degradation in the BL-11 group. Virulence genes governing biofilm formation (gtfB, gtfC, gbpB) and acid tolerance (ldh, atpD, fabM) were downregulated by 49-65%. These findings demonstrate that BL-11 attenuates experimental caries through multiple complementary pathways, providing a biological rationale for probiotic-based adjunctive caries prevention. Well-designed clinical trials are warranted to evaluate translational applicability in human populations.