Effect of fluoridated dentifrices on dentin erosion-abrasion in situ

Objective: This in situ/ex vivo study assessed the effect of different concentrations of fluoride in dentifrices on dentin subjected to erosion or to erosion plus abrasion. Methods: Ten volunteers took part in this crossover and double-blind study performed in 3 phases (7 days). They wore acrylic palatal appliances containing 4 bovine dentin blocks divided in two rows: erosion and erosion plus abrasion. The blocks were subjected to erosion by immersion in a cola drink (60 s, pH 2.6) 4 times daily. During this ex vivo erosion, the volunteers brushed their teeth with one of the dentifrices (Duraphat-D: 5,000 ppm F, NaF, silica; Crest-C: 1,100 ppm F, NaF, silica and placebo Duraphat-P: 22 ppm F, silica). Then, the respective dentifrice slurry (1:3) was dripped on dentin surfaces. While no treatment was performed in one row, the other row was brushed using an electric toothbrush for 30 s ex vivo. The appliances were replaced into the mouth and the volunteers rinsed with water. Dentin loss was determined by profilometry and analyzed by 2-way ANOVA/Tukey test (p<0.05). Results: For the condition erosion plus abrasion, the wear was significantly higher (3.23 ± 0.87 µm) compared to erosion alone (2.87 ± 0.67 µm). Regarding the different fluoride concentrations, the wear was significantly higher for the P (3.74 ± 0.90 µm) compared to the D (2.73 ± 0.85 µm) and C (2.69 ± 0.56 µm) dentifrices, which were not significantly different from each other. Conclusion: It can be concluded that the presence of fluoride concentrations around 1,100 ppm in dentifrices is important to minimize dentin wear by erosion and erosion+abrasion, but the protective effect is not increased along with the fluoride concentration. Supported by FAPESP (Proc 06/07260-4).