The production of dental plaque and caries by the bacterium Streptococcus salivarius in gnotobiotic WAG/RIJ rats.

The abilities of ten strains of Streptococcus salivarius to colonize rat molars and to induce caries were determined using mono-infected germ-free rats. Scanning electron microscopy revealed the production of micro-colonies and spheroids by Strep. salivarius on exposed surfaces of molar teeth, and abundant dense plaque formation in fissures. Most strains colonized fissures and smooth surfaces as effectively as Streptococcus mutans NCTC 10832, yet produced no buccal or lingual lesions. The four K- strains of Strep. salivarius produced more approximal lesions than the K+ strains but fewer lesions than Strep. mutans. All but one Strep. salivarius strain fell into the high-caries category, together with Strep. mutans. They were all more cariogenic than either Streptococcus milleri NCTC 11169 or Streptococcus faecalis 47.