Occurrence of the family bifidobacteriaceae in human dental caries and plaque

Despite the constant presence of members of Bifidobacteriaceae in the human oral cavity, few studies as their occurence in this habitat have been made. The presence and the distribution in human plaque and dental caries of Bifidobacterium dentium, Scardovia inopinata and Parascardovia denticolens, all belonging to the family Bifidobacteriaceae, were studied. The identification to species level was based on morphological and growth type features, fermentation tests, polyacrylamide gel electrophoresis of the soluble proteins and DNA-DNA homology. The three species, isolated on propionic-acid Trypticase-Phytone-Yeast extract medium, were present in 13 out of 19 and in 11 out of 15 subjects examined for dental caries and plaque, respectively. Scardovia inopinata was the species most frequently isolated in dental caries, whereas Bifidobacterium dentium was more numerous in dental plaque. The prevalence of Parascardovia denticolens was similar in the two habitats. In conclusion the prevalence of bifidobacteria species (Bifidobacterium dentium, Parascardovia denticolens, Scardovia inopinata) in respect to not bifidobacteria isolates is significantly different in caries versus plaque samples (p < 0.0001; X-square test).