Probiotic bifidobacteria and lactobacilli in oral health - interactions with biofilms and the host

Abstract

Probiotic bacteria confer a health benefit to the host when administered in adequate amounts. Usually probiotics belong to the genera of Lactobacillus and Bifidobacterium. Dental caries and periodontal diseases are common oral microbial diseases characterized by a dysbiosis in oral microbiota. Introducing probiotics into the oral cavity is suggested as supporting therapy or prevention also in caries and periodontal disease. Probiotics may enhance gingival health, but their acidogenic properties might be harmful from the cariological point of view.

The aim of this thesis was to study the following aspects of probiotics: their cariogenic properties, integration and actions in oral biofilms, and effects on health-related oral microbiota and host response. The work included in vitro and clinical studies with probiotic bacterial strains: L. reuteri ATCC 55730 and ATCC PTA 5289, L. rhamnosus GG (LGG), B. animalis subsp. lactis BB‐12 (BB‐12), and oral Bifidobacterium isolates.

Probiotic L. reuteri exerted cariogenic properties, when the environment was favorable, and the studied strains differed in their adhesion and capacity for biofilmformation. BB‐2 and oral bifidobacteria integrated into oral biofilms in vitro. They inhibited the growth of P. gingivalis and were inhibited by S. mutans. In a clinical study, BB‐12 and LGG had no effect on the oral microbiota in young healthy adults, but they had a positive effect on gingival health by reducing plaque and gingival indices, and by affecting salivary MMP‐9 and TIMP‐1 levels.

In conclusion, probiotic effects are strain specific and dependent on environmental factors. The effect on S. mutans or total oral microbiota seems to be limited. However, probiotics may have promising effects on gingival health by direct microbial interactions and immunomodulation.