Purpose: To evaluate the effect of a combination of fluoride dentifrice and acidulated phosphate fluoride (APF) on enamel with incipient caries lesions.
Materials and methods: Bovine dental enamel blocks with artificial caries lesions were divided into four treatment groups and submitted to a pH-cycling model: (1) Placebo non-fluoridated dentifrice (PD); (2) Fluoridated dentifrice (FD), 1,100 ppm F; (3) APF (12,300 ppm F, pH 3.5) + PD; 4) APF+FD. APF was applied to enamel blocks of groups APF+PD and APF+FD before the pH-cycling regimen and all of them were exposed to dentifrice during the cycling.
Results: The results showed that 61-81% of the fluoride previously deposited in enamel by APF was released to the media during the pH-cycling. The final concentration of fluoride in enamel in the group APF+PD was lower than that before the cycling (P < 0.05), but in the group APF+FD the reduction was not significant (P> 0.05). FD treatment was significantly more efficient than PD in rehardening the enamel surface and increasing the hardness of the caries lesions. APF+PD treatment was not more efficient than PD in increasing enamel hardness and an additive effect of APF+FD was not observed.