CaF2 formed on dentine by APF-gel application and its retention

Calcium fluoride (CaF₂) formed on dentine by professional fluoride (F) application could be retained for a longer time as a F reservoir if the patient used F-dentifrice, but this hypothesis has not been tested. Objective: This study (Ethical Committee Approval 039/2006) aimed to evaluate the retention of CaF₂ on root dentine pre-treated with acidulated phosphate fluoride gel (APF-gel) and subsequently subjected in situ to a high cariogenic challenge under daily use of F-dentifrice. Methods: Twelve adult volunteers wore palatal appliances, containing 2 bovine root dentine slabs, which were subjected during 2 experimental phases of 7 days each to a high cariogenic challenge (plaque accumulation and 20% sucrose exposure 8x/day) and to the following treatment groups: APF + non-F dentifrice (NFD) and APF + F dentifrice (FD; 1100 ppm F as NaF). The dentifrices were used 3 x/day and the dentine slabs were pre-treated with APF-gel 1.23% F (pH = 3.6-3.9) for 4 min. On the 8^th day of each phase, F concentrations as CaF₂ and fluorapatite (FA) were determined in dentine slabs. As control, APF-gel was applied on 2 dentine slabs per volunteer, which were not submitted to the in situ experiment (APF group). Results: The results (mean ± sd; n=12) of CaF₂ and FA (µg F/cm²) for APF, APF+NFD and APF+FD groups were respectively: 54.5±15.0a; 5.0±3.5b; 11.4±5.9c and 9.8±2.0a; 21.0±4.3b; 24.0±5.1b. Distinct letters denote significant statistical difference among the groups (p<0.05). Conclusion: The data suggest that F-dentifrice may increase the retention time of CaF₂ formed on dentine by APF-gel application, even under high cariogenic challenge, but the use of F-dentifrice does not affect FA concentration, which in fact increased in both in situ conditions studied. (Supported by FAPESP 05/03090-4).