Fluoride Uptake after APF Gel Application and its Retention after Cariogenic Challenge and Fluoridated Dentifrice Use

Acidulated phosphate fluoride (APF) application has been suggested for a high caries risk individuals. It forms a high amount of fluoride (F) in enamel, but the retention of the products formed under situations of high cariogenic challenge and fluoridated dentifrice (FD) use is not known. Objective: To evaluate the retention of F formed in enamel by APF application under high cariogenic challenge conditions and FD use. Methods: Volunteers (n=16), using a palatal acrylic appliance containing four bovine enamel blocks, were submitted to the following treatments: 1- APF gel + non-fluoridated dentifrice (APF+PD) and 2- APF+FD. APF gel was applied during 4 minutes to the enamel before the experimental period. Dentifrices (a slurry 1:3, w/w) and 20% sucrose solution were dripped onto the blocks 3x/day and 8x/day, respectively. After two-14-day phases, fluoride concentration in enamel was determined by removing three enamel layers using acid etching. F concentration was also evaluated in blocks without APF application (control group) and with APF application (APF group), but that were not submitted to cariogenic challenge. Results: F concentration (µg/g) at 10,3 ± 0,3 µm from enamel surface for the groups Control, APF, APF+PD and APF+FD was respectively: 944.6 ± 581.6a; 10505.2 ± 2775.0bc; 8901.4 ± 3900.0b; 11305.0 ± 2964.2c (p<0.05, for different letters). The F concentration in the other layers did not show statistical difference when compared with the control. Conclusion: The high F concentration found in enamel after APF application was maintained after the cariogenic challenge, but a higher F concentration was observed when fluoridated dentifrice was used, suggesting that the combination APF+FD can be relevant in terms of anticariogenic effect. (Supported by FAPESP Proc. 99/12080-0)