Effect of Dehydroacetic Acid and Tetracycline on Caries Activity and Its Transmission in the Rat

¹ National Institute of Dental Research, National Institutes of Health, Public Health Service, U.S. Department of Health, Education and Welfare, Bethesda, Maryland

When rats were pretreated with the antibiotic tetracycline before being placed on caries-producing diets, their subsequent caries activity was markedly reduced. This was ascribed to a reduction in the cariogenic microflora. Administration of dehydroacetic acid (DHA) in a caries test diet increased caries activity in the rat mainly on the smooth surfaces. Caries activity of DHA-fed animals was partially counteracted in the animals pretreated with tetracycline. Rats fed DHA for 28 days were conducive to no greater degree of caries activity than control animals of the same age when they were caged together with young, highly susceptible animals. Tetracyclinepretreated animals, on the other hand, transmitted a much lower level of caries activity under the same conditions, thus indicating a relatively stable alteration of the cariogenic flora.