Effects of probiotic fermented milk on biofilms, oral microbiota, and enamel

Abstract

The aim of this study was to evaluate in vitro and in vivo the effects of 2 brands of probiotic fermented milk on biofilms, oral microbiota, and enamel. For the in situ experiment, ten volunteers wore palatine devices containing four blocks of bovine dental enamel over 3 phases, during which 20% sucrose solution, Yakult ® (Treatment A), and Batavito ® (Treatment B) were dropped on the enamel blocks. Salivary microbial counts were obtained and biofilm samples were analyzed after each phase. For the in vivo experiment, the same ten volunteers drunk Yakult ® (Treatment C) and Batavito ® (Treatment D) in two phases. Saliva samples were collected for microbial analysis after each phase. The in situ study showed that in comparison with Treatment A, Treatment B resulted in fewer total cultivable anaerobes and facultative microorganisms in biofilms, higher final microhardness, lower percentage change in surface hardness, and smaller integrated subsurface enamel hardness. In the in vivo study, Treatment D resulted in a reduction in the counts of all microorganisms. The results suggested that the probiotic fermented milk Batavito ® , but not Yakult ® , reduced the amount of oral microorganisms and mineral loss in bovine enamel.

Inhibition of Streptococcus mutans by a commercial yogurt drink

“…Regarding whether Yakult ® reduced salivary levels of S. mutans , clinical studies showed controversial results 22, 23, 24, 25. The present study showed that Yakult ® could inhibit the growth of S. mutans .…”

“…This finding echoed with a clinical study showing that daily mouth-rinsing with Yakult ® for 7 constitutive days reduced salivary levels of S. mutans 22 . While three other studies did not show reduction of salivary levels of S. mutans after Yakult ® consumption,23, 24, 25 the reason for the inconsistent observation is still unclear. A potential explanation is that the study designs of these clinical studies varied and might not be standardized among studies, as suggested by systemic reviews 3 , 4 .…”

“…Enamel wear was shown to be restricted in superficial surfaces 38 24 , 39 . The pH values of dental plaque 39 and enamel demineralization 24 , 39 were not different between subjects taking Yakult ® or sucrose.…”

“…In situ studies compared plaque acidification and enamel demineralization in patients consumed commercial yogurt drinks or 20% sucrose by forming biofilms on bovine enamel slabs, which were placed in the oral cavity of human subjects 24 , 39 . The pH values of dental plaque 39 and enamel demineralization 24 , 39 were not different between subjects taking Yakult ® or sucrose. In contrast, another brand of yogurt drink increased pH values of dental plaque and reduced enamel demineralization 24 , 39 .…”

“…While sucrose is shown to reduce the susceptibility of S. mutans toward antimicrobial agents, 21 the sucrose-containing Yakult ® is reported to reduce salivary S. mutans in children whose salivary S. mutans level at baseline is higher than 10 5 colony forming units (CFU)/ml 22 . In contrast, three other studies report that salivary S. mutans levels are not significantly changed after consumption of Yakult ® 23, 24, 25. When the probiotic strain, L. casei strain Shirota, is shown to inhibit the growth of S. mutans , 8 , 12 the controversial results of clinical studies lead to a question: Could this sweetened probiotic beverage inhibit the viability of S. mutans ?…”