Since dentin is more susceptible to caries than enamel, dentin demineralization may be influenced more by application of additional fluoride. Authors of a study published in the Journal of Dental Research hypothesized that a combination of professional fluoride, applied as acidulated phosphate fluoride (APF), and the use of 1,100-ppm-fluoride dentifrice (FD) would provide additional protection for dentin compared with 1,100-ppm-fluoride alone. The study involved 12 adult volunteers who wore palatal appliances containing root dentin slabs. During 4 experimental phases of 7 days each the slabs were subjected to biofilm accumulation and sucrose exposure 8 times per day. The volunteers were randomly assigned to the following treatments: placebo dentifrice (PD); 1,100-ppm-FD; APF + PD; and APF + FD. APF gel (1.23% fluoride) was applied to the slabs once at the beginning of the experimental phase, and the dentifrices were used 3 times per day. The study found that APF and FD increased fluoride concentration in biofilm fluid and reduced root dentin demineralization, presenting an additive effect. Analysis of the data suggests that the combination of APF gel application and daily regular use of FD may provide additional protection against root caries compared with the dentifrice alone.
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