Objective: As the biofilm fluid is the site where the de- and remineralization processes occur, this study evaluated the effects of F concentration and pH in the biofilm fluid.
Method: Volunteers (n=23, 21-40 years old) were randomly assigned to brush with CD (1,100 µg F/g), LFD (550 µg F/g) and a placebo dentifrice (PD – F free), both at pH 4.5 and 7.0, comprising 6 treatments. They were instructed to brush 3 times/day with approximately 0.5 g of dentifrice (transversal technique) and to rinse after brushing with 10 mL of tap water, following a double-blind, crossover protocol. Biofilm samples were collected on the 7thday of dentifrice use, at 1 and approximately 12 h after brushing. The fluid phase of samples was extracted, buffered with TISAB III and analyzed using microelectrode techniques. Results were analyzed by 2-way repeated measures ANOVA and Tukey’s test (p<0.05).
Result: The use of acidic LFD and CD led to higher F levels in the biofilm fluid when compared to their neutral counterparts, at both times of sample collection. For samples collected 1 h after brushing, significant differences were seen among all acidic toothpastes, while for the neutral toothpastes the only significant difference was seen between PD and CD. For samples collected 12 h after brushing, no significant differences were seen in F concentrations in the biofilm fluid, except between acidic PD and CD.
Conclusion: The ability of acidic toothpastes in increasing biofilm fluid F concentrations seems to be one of the reasons by which these formulations present higher efficacy than neutral toothpastes.