Effect of fluoridated dentifrices on enamel erosion-abrasion in situ

Objective: This in situ/ex vivo study assessed the effect of different concentrations of fluoride in dentifrices on enamel 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 enamel 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 enamel 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. Enamel 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 compared to erosion alone. There were no significant differences among the dentifrices regarding enamel wear. Conclusion: It is concluded that the highly concentrated fluoride dentifrice did not have a protective effect on enamel erosion and erosion plus abrasion. Supported by FAPESP (Proc 06/04628-0).