Abstract
Dextranase AD 17 obtained from a culture liquor of a strain of Spicaria violacea was assessed for its ability to inhibit the development of dental caries in conventional Sprague-Dawley rats which had been infected with one of the Streptococcus mutans strains, MT6R (serotype c), OMZ 176R (d), or MT703R (e). These experiments showed that caries was significantly inhibited when rats were given cariogenic diet # 2000 and drinking water containing AD 17 at a concentration of 10 units/g, as compared to control rats not given dextranase. The inhibitory effects of AD 17 were more prominent in smooth surface caries than in total caries. AD 17 had a tendency to retard both the establishment of inoculated S. mutans and plaque deposition on tooth surfaces. However, S. mutans could be implanted in the rat oral cavity after repeated inoculation of the bacteria, even in the presence of AD17. These results suggest that the anticaries activity of AD17 is due to not only inhibition of adherence of S. mutans cells on tooth surfaces but also to physicochemical changes of dental plaque formed under the enzymatic action of AD17. Preliminary histopathological examination showed that AD17 had no significant toxicity in rats.
