Human strains of mutans streptococci show different cariogenic potential in the hamster model

The cariogenic potential of fresh humans strains of Streptococcus mutans and Streptococcus sobrinus was examined in hamsters maintained on a high sucrose diet. The strains 1B 16 (S. mutans) and B13 (S. sobrinus) isolated 20-25 yrs ago served as positive controls. Three series of experiments were run. Some strains were tested once and some strains were tested in all 3 experiments. The animals infected with S. sobrinus strains generally showed lower caries scores than those infected with S. mutans strains. Among the groups infected with the different strains of S. mutans the caries scores varied. In one of the experiments the caries score of the animals infected with one of the Icelandic S. mutans strains was significantly higher than that of the positive control group and the group infected with one of the fresh Swedish isolates. Thus, different strains of mutans streptococci where shown to induce varying caries activity in the hamster model.