In situ remineralisation of enamel and dentin after the use of an amine fluoride mouthrinse in addition to twice daily brushings with amine fluoride toothpaste

It is often claimed that 3 fluoride moments a day significantly reduce the caries risk compared to 2 daily fluoride moments. However, previous research is not conclusive. Therefore, the aim of this study was to compare the effect on lesion progression of 2 versus 3 fluoride moments a day. A double-blind, randomized, cross-over in situ experiment was designed. The experiment comprised 2 in situ periods of 3 weeks with a washout period of 3 weeks in between. Sixteen participants wore an enamel and a dentine specimen with a preformed lesion placed buccally in their partial prosthesis. The participants brushed twice a day with a 1,400 ppm F (amine fluoride) toothpaste and rinsed once a day with either 250 ppm F (amine F/NaF) or a placebo rinse. At the end of the experiment the specimens were retrieved for fluoride analysis and the assessment of integrated mineral loss with transversal microradiography. The fluoride analysis showed a statistically significant increase in structurally bound fluoride in dentine, but not in enamel, when comparing the fluoride mouthrinse group with the placebo rinse group. The amounts of loosely bound, KOH-soluble fluoride were not different between both groups neither for enamel nor for dentine. In dentine IML gain was significantly (p < 0.05) higher for the fluoride mouthrinse group than for the placebo mouthrinse group. In enamel no statistically significant differences in IML gain were found. For dentine a third fluoride moment may be beneficial in enhancing remineralisation, even under the remineralising conditions as in this study.