Potential cariogenicity of Lycasin 80/55 before and after repeated transmissions of the dental plaque flora in rats.

Five successive experiments, with rats fed ad libitum on diets containing sucrose or Lycasin 80/55, were carried out. In experiment I, the rats were inoculated with Streptococcus mutans alone or with Strep. mutans in combination with Actinomyces viscosus. In three successive transmission experiments (II, III, IV), the rats were inoculated with plaque of the rats of the preceding experiment. The rats of experiment V were inoculated with the original strains or with plaque derived from experiment IV. After five successive transmissions of the plaque flora, no alterations were demonstrated in the numbers and percentages of Strep. mutans and A. viscosus or in the fermentation rate of Lycasin by the plaque flora in vitro. Lycasin 80/55 was virtually non-cariogenic compared with sucrose (p less than 0.001) irrespective of whether the rats were inoculated with Strep. mutans alone or in combination with A. viscosus, with the original strains or with plaque from the preceding experiments with rats on a Lycasin 80/55-containing diet.

Establishment and localization of mixtures of Streptococcus mutans serotypes in the oral cavity of the rat.

The colonization of S. mutans serotypes on different tooth surfaces of the rat was investigated. Fissures appeared to be the main habitat. In the presence of a serotype c strain, S. mutans serotype d could only be established when sucrose-containing diets were supplied. However, the serotype c strain was always present in higher proportions. The production of a bacteriocin for which the serotype d strain was sensitive appeared to be responsible for the observed predominance of the serotype c strain.