Factors involved in the intraoral retention of fluoride after the use of fluoridated dentifrices

Abstract

This study aims to evaluate the influence of pH and viscosity of fluoridated dentifrices on intraoral fluoride (F) retention in children from a fluoridated community. During the first phase, it will be determined F and calcium (Ca) concentrations in saliva, dental biofilm and biofilm fluid after 14 days of using dentifrices containing 0, 550 and 1,100 ppm F (NaF), buffered at pH 4.5 and 7.0, accounting for 6 possible combinations. Children (n=25) will receive dental prophylaxis before the beginning of each experimental period, and they will brush their teeth with a F-free dentifrice for 2 weeks (wash-out). During each experimental period children will be randomly assigned to brush twice daily with one of the dentifrices, following a double-blind, crossover design. Saliva and biofilm samples will be collected on the 14th day after starting using the dentifrices, 1 and 12 h after the last toothbrushing. This will be repeated for 5 additional weeks, in order to follow the crossover protocol. The influence of the dentifrice's viscosity on F and Ca concentrations in saliva, dental biofilms and biofilm fluid will be evaluated in the second phase, following the same protocol described for the first phase. The products will be manufactured in 3 different viscosities (low, medium and high), buffered at pH 4.5. Saliva and biofilm fluid samples will be analyzed for F with the F inverted electrode (samples immersed in mineral oil) after buffering with TISAB III. F in whole biofilm will be analyzed, after HCl extraction, as described for saliva and biofilm fluid. Ca will be analyzed by spectrometry (Arsenazo III). The data will be analyzed regarding distribution (normality and homogeneity) before determining the appropriate statistical tests. If parametric analysis is possible, data will be analyzed by ANOVA (repeated measures) and Tukey's test. Otherwise, Kruskall-Wallis' and Dunn's tests will be used. Linear regression analysis will be performed to verify the relationship between F and Ca concentration in the samples. A 5% significance level will be selected.