Inhibition of Rat Dental Caries by Dextranase from a Strain of Spicaria violacea

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 MT-703R (e). These experiments showed that caries was significantly inhibited when rats were given cariogenic diet #2000 and drinking water containing AD17 at a concentration of 10 units/g, as compared to control rats not given dextranase.The inhibitory effects of AD17 were more prominent in smooth surface caries than in total caries. AD17 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 AD 17. 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 AD 17. Preliminary histopathological examination showed that AD17 had no significant toxicity in rats.

Biology, immunology, and cariogenicity of Streptococcus mutans.

“…In subsequent studies, a(1-6) glucanases of different origins effectively prevented plaque formation and caries induction by S. mutans strains in hamsters (155, 159, 161). Similar positive results have been obtained with other animal model systems (25,227,228,463).…”

Expression and secretion of an Arthrobacter dextranase in the oral bacterium Streptococcus gordonii

“…In the prevention of dental caries, dextranase is one of the effective agents which digest the 1,6-a-glucoside bond of water-insoluble glucan on the tooth surface, and dextranase significantly inhibits the production of water-insoluble glucan and the adherence of mutans streptococci cells in vitro (8,11,15,23,28). However, rigorous use of mouth rinses that contain highly concentrated dextranase is necessary for the dispersion and prevention of bacterial plaques in vivo (2,4,7,12,17,24). The development of more effective delivery methods would aid the prevention and control of bacterial plaque infections on teeth.…”

“…Dextranase is an enzyme which hydrolyzes the 1,6-a-glucosidic linkages of glucan and is known to repress the adherence of mutans streptococci to the tooth surface in vitro (8,11,15,23,25). This enzyme also retards plaque deposition on the tooth surface and thus inhibits dental caries in experimental animals (2,7,12).…”