Artificial enamel dental caries treated with different topical fluoride regimes: an in situ study

To evaluate whether the topical fluoride application (acidulated phosphate fluoride, APF) at high concentration has an additional effect on the control of enamel lesions compared to fluoride dentifrice (FD; low concentration). The frequency of APF treatment on the arrestment of caries lesions and the amount of fluoride deposited on enamel after application of high and low fluoride concentrations were also evaluated.

Five subjects wore partial dentures with in vitro demineralized blocks during 35 days. All specimens (5p/subject) were brushed three times daily for 1 min with FD (1100 ppmF). Besides the FD treatment, four specimens were submitted to APF gel topical applications (12,300 ppmF) on weekly intervals (one to four applications). The enamel blocks were analyzed at baseline, after demineralization and after intraoral procedures regarding: surface roughness (SR), clinical aspects (brightness and texture), surface microhardness (SMH) and enamel fluoride content. Friedman's test was used to compare SMH and SR among the treatments. Analysis of variance, followed by Tukey's studentized range test, was used to evaluate fluoride content and SR among the groups. The significance level used was 5%.

Changes in surface brightness, texture and SR were not detected. FD+3 APF and FD+4 APF were the only treatments capable of increasing SMH values and fluoride content compared to demineralized blocks (p < 0.001), although no differences could be observed within the treatments.

This study showed that > or = 3 APF in addition to FD enhance enamel rehardening and produce a larger reservoir of fluoride.