Reproducibility of dental caries in Balb/c mice induced by the bacterium Streptococcus mutans

Dental caries induced by infection with Strep. mutans C67-1 (serotype c) or Strep. mutans 50B4 (serotype d/g) and feeding a 30 per cent sucrose-containing diet was found mainly in fissures; smooth surface caries was not detected. A decrease in the mean caries score was observed with time, coinciding with lower recoveries of Strep. mutans at the end of the experimental period. The decrease in caries formation may be attributed to changes in some of the cariogenic properties of the individual Strep. mutans strains during maintenance in the laboratory, as re-isolation of the strains from caries-active mice yielded similar and reproducible caries scores to those in early experiments. Hence Balb/c mice can be used as an experimental model in caries research, provided that great care is taken in selecting and storing the bacteria.