The effects of fluoride on the growth of oral streptococci

Four species of oral streptococci were examined for their ability to grow in a complex medium supplemented with NaF, and at various pH levels. Streptococcus mutans strains were the most susceptible to inhibition, with Streptococcus mitior and Streptococcus sanguis being the least affected. The S. mutans genotype comprising serotypes c, e and f was more susceptible to inhibition by fluoride than was the genotype comprising serotypes d and g. The results suggest that the fluoride concentration of dental plaque might influence the relative proportions of the species of streptococci found in dental plaque.