Methods: Two hundred and twelve children aged 2-4 years old, with or without active caries lesions were randomly allocated into 3 groups differing according to the type of dentifrice used over 12 months: G1 (n=39-Active/38-Inactive): 550µgF/g-pH4.5; G2 (n=33-Active/35-Inactive): 1100gF/g-pH7.0; G3 (n=33-Active/34-Inactive): 550µgF/g-pH7.0. Clinical examination was performed at baseline and after 12 months of study, using the diagnostic criteria for caries activity (active, inactive) and surface integrity of the lesion. The number of lesions becoming active/cavities or inactive were evaluated, determining whether the lesions had progressed or regressed, respectively. The net increment (progression - regression) was also recorded for each child. Plaque samples were collected 5 and 60 minutes after the last use of the dentifrices, 6 months after the study had begun. Data were analyzed by ANOVA and Bonferroni tests or Kruskal-Wallis and Dunn tests (p<0.05). In all cases, the level of significance was set at 5%.
Results: Despite a numerical difference in caries increment after 12 months (G3>G2>G1), no significant differences were detected among the groups. Fluoride concentrations in toenails were significantly lower for children that used the liquid dentifrices with low fluoride concentration (p<0.05). The reduction of pH was able to enhance the uptake of fluoride in plaque, although the differences among the dentifrices or times did not reach statistical significance. Plaque F levels did not decrease along time.
Conclusions: It can be concluded that a low fluoride and low pH dentifrice can be effective for controlling dental caries without increasing the risk of dental fluorosis in young children.