Abstract
It has been recommended that fluoride dentifrice (FD) should be used twice a day to control enamel caries, but higher frequencies have not been experimentally assessed. Besides, dentin is considered more susceptible to caries than enamel, and the effect of FD frequency of use for controlling root caries may be different from that necessary to control coronary caries. The present study will evaluate the effect of frequency of FD (0, 1, 2, or 3x/day) on enamel and dentin demineralization, under conditions of biofilm accumulation and high sucrose exposure. An in situ, crossed, double-blind study, split mouth regarding to dental substrates tested, will be conducted during 4 phases of 14 days each. Sixteen volunteers will wear palatal devices containing dental slabs, four of enamel and four of root dentin, of known surface hardness. The treatments will be: G1 = Brushing with fluoride placebo dentifrice (PD) 3x/day (after the main meals); G2 = Brushing with FD 1x/day, in the morning before sucrose exposures, and 2 brushings with PD after lunch and after the last sucrose exposure; G3 = Brushing with FD 2x/day (in the morning, before the first cariogenic challenge, and at night after the last challenge) and one brushing with PD after lunch. G4 = Brushing with FD 3x/day (in the morning, before sucrose exposures, after lunch, and at night after the last exposure). It will be used a FD NaF/SiO2-based containing 1,100 ppm F and its placebo, and 20% sucrose solution will be dripped extra-orally on slabs 8 times a day. At the end of each phase, the biofilms formed on the dental slabs will be collected separately for analysis of fluoride concentration in the fluid and in solids part. Enamel and dentin demineralization will be estimated by percentage of microhardness loss and by cross-sectional microhardness of the blocks. Fluoride uptake by enamel and dentin will also be determined. These response variables will be statistically assessed at 5%. It is expected that the present study contributes for the knowledge on the importance of FD frequency of use for enamel caries control, and also to generate new evidences on the effect for root caries control. (AU)
|