[Microflora in a controlled caries model study in rats]

Changes of dental plaque were investigated in Osborne-Mendel-rats under the influence of a sucrose-containing diet as well as the inhibition of it by antibiotics (streptomycin, erythromycin, penicillin) in order to find out the optimal conditions of animal association with Str. mutans (OMZ 176). The cariogenic diet did not alter the isolated total germ numbers, but modified the flora to a streptococcal one. The application of an erythromycin/penicillin mixture caused a 100 fold decrease of the germ number and streptococcal elimination so that an association of the germ Str. mutans detectable by microbiological methods could take place at this moment. The obtained caries scores differed from the non-contaminated group. Mono-associated gnotobiotic Wistar rats developed more carious lesions than conventional animals of the same strain; therefore Str. mutans OMZ 176 was classified as high cariogenic.