F-Dentifrice Overcomes the Lower Resistance of Fluorotic Enamel to Caries

Objectives: The objective of this study was to assess if fluoride dentifrice (FD) could make fluorotic enamel more resistant to the caries process.
Methods: Paired enamel slabs (n=20/group) from human teeth presenting Thylstrup and Fejerskov (TF) fluorosis scores from 0 to 4 were obtained. Half of the anatomic surface of enamel slabs was isolated and used as a control (baseline) for enamel hypomineralization and fluoride concentration. The slabs were submitted into a pH-cycling model simulating simulating the process of a high cariogenic challenge and 2x/day they were treated with placebo dentifrice (PD) or FD (1,100 µg F/g, as NaF, Tandy^®). After 10 days, the area of enamel demineralization (DS) was evaluated by cross sectional microhardness, and fluoride formed (FF) was determined with ion specific electrode after enamel acid etching. The values of DS and FF found were subtracted from the baseline data. The data of net demineralization area (DDS; kg/mm² x µm) and FF (µg F/g) for TF 1 to 4 were grouped as TF1-2, and TF3-4, and TF0; they were analyzed by two-way ANOVA followed by Tukey’s test (a=5%).
Results: The effect of the factors (fluorosis and dentifrice treatments) was statistically significant for DDS and FF (p<0.05). FD was effective in reducing demineralization and increasing fluoride in enamel (p<0.05). When the treatment was made with PD, the order of demineralization was TF3-4>TF1-2>TF0 (p<0.05) but these groups did not differ when FD was used (p>0.05). In terms of FF, the groups did not differ when PD was used but the group TF3-4 presented higher concentration when the treatment was made with FD.
Conclusions: These findings suggest that the higher susceptibility of fluorotic enamel to develop carious lesions can be modified by fluoride dentifrice treatment.