To determine the effects of fluoride and pH on enamel de- and remineralization, a study by Dr. Frank Lippert, et al used quantitative light-induced fluorescence to investigate enamel lesions under conditions designed to resemble plaque fluid. Preformed enamel lesions were exposed to partially-saturated lactic acid solutions with varying fluoride concentrations (0.0 ppm, 0.1 ppm, 0.5 ppm, 1.5 ppm, and 4.0 ppm) and pH levels (4.9, 5.2, and 5.5). The average fluorescence loss was monitored for 11 days. Then, the enamel lesions were demineralized in a partially-saturated acetic acid solution for 2 periods of 24 hours each. The lesions in the plaque fluid of a 4.0-ppm fluoride concentration and a 5.5-pH level were found to show the most remineralization after 11 days and the most demineralization after exposure to acetic acid. Increasing the fluoride concentration resulted in more remineralization regardless of the pH level, and increasing the pH level resulted in more remineralization. The lesions exposed to no fluoride showed no remineralization regardless of the pH level. The study found that fluoride had a stronger effect on remineralization and net mineral change than pH.
