Enamel fluoride uptake of a novel water-based fluoride lacquer
Objective: Aim of the in-situ-study was to evaluate fluoride retention in sound and demineralised enamel after application of the novel water-based fluoride (0.15% F) lacquer Mirafluorid (Hager & Werken, Germany) compared to the resin-based varnish (2.23% F) Duraphat (Colgate, USA). Methods: Each five enamel specimens were prepared from 60 bovine incisors. In 150 of these specimens incipient lesions were produced with acidic hydroxyethylcellulose (pH: 4.8; 72 h), 150 specimens were not demineralised. The samples were equally allotted to three groups (A: Mirafluorid, B. Duraphat, C: control). Each 80 specimens (40 demineralised, 40 sound) were varnished with either Mirafluorid or Duraphat or remained unfluoridated (controls). The other specimens were used for measuring base-line fluoride content of the respective tooth. Each six specimens (3 demineralised, 3 sound) were fixed in intraoral appliances worn for five days by 10 volunteers in three series (A-C). During the experiment, the samples were brushed twice daily with a fluoridated toothpaste. KOH-soluble and structurally bound fluoride (0-30µm and 31-60µm depth) were determined immediately, one day, three days and five days after fluoridation. Fluoride uptake was calculated as compared to baseline-content and statistically analysed (Wilcoxon-test). Results: Immediately after fluoridation, uptake of KOH-soluble and structurally bound fluoride was similar for Mirafluorid compared to Duraphat in both demineralised and sound enamel. However, at day 1, 3 and 5 statistically significantly higher amounts of KOH-soluble and structurally bound fluoride were found in the samples treated with Duraphat. Moreover, as compared to the controls (C), fluoride uptake in the Mirafluorid samples was significantly higher for KOH-soluble fluoride and fluoride in the 1st enamel layer (0-30µm), but not in the 2nd layer. Conclusion: The novel fluoride lacquer Mirafluorid deposits less KOH-soluble and structurally bound fluoride on both demineralized and sound enamel compared to Duraphat under in-situ-conditions.