The effect of pH and fluoride concentration of liquid dentifrices on caries progression.

OBJECTIVE: This randomized clinical trial evaluated the effect of pH and fluoride concentration of liquid dentifrices (LD) on caries progression and fluoride uptake in the toenails of 2-4-year-old children. MATERIALS AND METHODS: Schoolchildren living in a fluoridated area, with (A) or without (I) active caries lesions, were randomly allocated into three groups according to the LD they would use over 12 months: group 1 (n = 48-A/56-I): 550 mug fluoride (F)/g, pH 4.5; group 2 (n = 56-A/48-I) 1,100 mug F/g, pH 7.0; and group 3 (n = 52-A/55-I): 550 mug F/g, pH 7.0. The number of lesions becoming active/cavities or inactive was clinically evaluated by determining progression or regression. Additionally, white spot lesions were evaluated by the quantitative light-induced fluorescence (QLF) method in 75 children. Toenail fluoride concentration was also evaluated. Data were analyzed by ANOVA and followed by Dunn's test or ANCOVA followed by Tukey's test (p < 0.05). RESULTS: Caries net increment followed a decreasing pattern according to the dentifrice used (G1 < G2 < G3), regardless caries activity, but significant differences were detected only for caries progression and net increment (G1 < G3) for the caries-active group when evaluated through visual inspection. For the regression, the values found for the three groups were more similar, without significant differences. QLF analysis detected no significant difference between groups 1 and 2, but they performed significantly better than group 3. A significantly lower toenail fluoride concentration was observed when children used the low-fluoride dentifrices. CONCLUSION: The low-fluoride acidic LD has good potential to prevent caries and reduce fluoride intake. CLINICAL RELEVANCE: The low-F acidic dentifrice combines the desirable characteristics of caries prevention and reduced fluoride intake-for a product to be used by children, regardless their caries status.