Abstract
Ionic fluoride and HPO 2-4 concentrations were determined in partially-decalcified enamels before and after exposure to NaF or MFP toothpastes, to determine whether fluoride uptake could be attributed to reactions with HPO2- 4. Acid phosphate concentrations did not alter upon exposure to fluoride, even though large uptake of fluoride did occur. Infra-red spectroscopy showed HPO2-4 in artificially decalcified enamel to be adsorbed rather than present as a discrete secondary orthophosphate.