title: Effect of fluoride on growth and acid production by Streptococcus mutans in dental plaque.
abstract: The aim of this study was to measure the effect of fluoride on the production of organic acids by Streptococcus mutans in dental plaque. The effect was studied in a simplified model of dental plaque with gnotobiotic rats monoinfected with S. mutans Ny341. Adaptation of S. mutans to fluoride was induced by feeding one group of the rats on fluoride-containing diet and drinking water. No difference was found in the accumulation of S. mutans on the teeth between the fluoride-adapted and the control groups. However, there was a significant difference in the amount of lactic acid in metabolically resting plaque between the groups, lactic acid being lower in the fluoride-adapted plaque. At 5 min after a rinse containing 10% sucrose, a high level of lactic acid was found in plaque from animals not exposed to fluoride. Rinses containing 4 or 20 mM fluoride before the sucrose rinse significantly inhibited the lactic acid production in the control group. In the plaque from rats on fluoridated diet and drinking water the sucrose-induced production of lactic acid was not inhibited by a 4 mM fluoride rinse. Moreover, the production of lactic acid in the fluoride-adapted plaque was prolonged. The results indicate that due to fluoride adaptation the inhibition of acid production is unlikely to be important for the caries-preventive action of fluoride.
mesh_terms: D000085:Acetates / Q000378:metabolism; D019342:Acetic Acid; D000818:Animals; D003773:Dental Plaque / Q000382:microbiology*; D004195:Disease Models, Animal; D005459:Fluorides / Q000494:pharmacology*; D005561:Formates / Q000378:metabolism; D005856:Germ-Free Life; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D051381:Rats; D013295:Streptococcus mutans / Q000187:drug effects / Q000378:metabolism
chemical_list: D000085:Acetates; D005561:Formates; D007773:Lactates; C030544:formic acid; D019344:Lactic Acid; D019342:Acetic Acid; D005459:Fluorides