Probiotic bifidobacteria are widely consumed and they are beneficial for gut health. Yet, the effects of bifidobacteria on oral health are poorly understood - they may affect both dental health and disease. In addition, some Bifidobacterium species have been suggested to have a role in periodontal health. The aim of this in vitro study was to investigate the integration of probiotic Bifidobacterium animalis subsp. lactis Bb12 (Bb12) in oral supragingival and subgingival biofilm models. In addition, the viabilities of the major oral pathogens Streptococcus mutans and Porphromonas gingivalis in the biofilms with Bb12 were studied.
Methods:
Oligospecies biofilms were prepared on saliva coated hydroxyapatite (HA) by using a modified Zurich biofilm model (Guggenheim et al. 2001). The supragingival biofilm model consisted of S. mutans, Actinomyces naeslundii and Bb12 and the subgingival model of P. gingivalis, A. naeslundii, Fusobacterium nucleatum and Bb12. Biofilms were incubated for 18 or 42h at 37°C in an anaerobic atmosphere. The medium (FUM) was renewed at the 18h timepoint. After incubation, the pH was measured and the bacterial samples were cultivated on selective agar plates to count the number of different bacteria in each biofilm.
Results:
Bb12 integrated both in supragingival and subgingival biofilm models. It did not affect the pH of the biofilm medium or the number of S. mutans in the biofilm, but a lower amount of P. gingivalis was cultivated in subgingival biofilm model after 42h with Bb12 than without it (Mann-Whitney U-test, p=0.009). In addition, Bb12 enhanced the growth of A. naeslundii in the subgingival biofilm model (p<0.001).
Conclusions:
Bb12 can be integrated in a cariogenic or a periodontal biofilm model and it may also modify the bacterial composition of the biofilm associated with periodontal disease.