Effect of sodium and amine fluoride treatment on adsorption and ultrastructure of S. mutans and S. sanguis

A new modification of hydroxyapatite (HA) adherence assay is presented to study the effect of two chemically different fluorides, sodium fluoride (2% solution) and amine fluoride (Elmex sol. concentrate) on the adsorption of S. mutans (ATCC 27351) and S. sanguis (ATCC 10556). Vaseline-coated glass rods were rolled in HA powder, after which the rods were either coated or not coated with salivary pellicle. Both strains adsorbed better to saliva-coated rods. Pretreatment of the rods with fluorides did not much affect the adsorptions. Treatment of bacteria with the fluorides, however, very significantly reduced the adsorption in both strains (P less than 0.001). The fluoride treatments also reduced bacterial viabilities, and electron microscopy revealed a distinct toxic effect, in particular among the amine fluoride treated specimens.