Objectives: The purpose of the work was to establish the level and source of salivary fluoride, whether it could interact with tooth mineral and whether it was able to effect calcium re-acquisition and remineralisation.
Methods: Fluoride in saliva and in solution was measured by electrode, calcium by complexometric titration and phosphate colourimetrically-to measure salivary fluoride, its uptake by mineral and the effects of such low levels on calcium and phosphate levels in solution in contact with suspensions of mineral hydroxyapatite.
Results: Fluoride levels in saliva were low but could interact with hydroxyapatite. Such levels caused apatite crystallite growth and preferential acquisition of calcium by calcium-deficient apatite.
Conclusions: Salivary fluoride contents rose with increasing water fluoride levels. It was acquired by hydroxyapatite mineral. Topical fluoride was stored on oral tissues. Even these low fluoride contents could cause mineral crystallite growth with preferential calcium uptake. On a mineral area basis these effects were caused by quite low fluoride uptakes. These findings do not support reliance upon large fluoride uptakes by tooth enamel as evidence for commensurate caries reductions.