Effect of application of acidulated phosphate fluoride and use of fluoridated dentifrice in demineralization of dentine exposed to a high cariogenic challenge

Abstract

The association of acidulated phosphate fluoride and use of fluoridated dentifrice has not been tested yet for prevention and control of caries of root dentine, which might be important, since there is a increasing prevalence of such lesions, particularly in elderly population. Thus, the objective of this study is to evaluate in situ the effect of association of application of acidulated phosphate fluoride and fluoridated dentifrice on biochemical and microbiological composition of biofilm and demineralization of root dentine caries under a high cariogenic challenge. For this, an in situ crossed study will be conducted and 12 adult volunteers will wear a intra-oral palatal appliance containing 6 blocks of sound bovine dentine, which will be submitted to 4 groups of treatment: (1) Non-fluoridated dentifrice; (2) Fluoridated dentifrice (1100 ppm of F as NaF); (3) Topical F application + non-fluoridated dentifrice; (4) Topical F application + fluoridated dentifrice. The topical F application with acidulated phosphate fluoride will be performed on the first day of the experimental phase and in the anterior part of the appliance 2 dentine blocks will be placed, which will be removed soon after for determination of loosely bound F and firmly bound F. The volunteers will brush the teeth and appliance 3 x/day with the dentifrices designed for each phase. 20% Sucrose solution will be dripped over the blocks 8 x/day. At the end of each experimental phase, the acidogenicity of the biofilm will be determined and the biofilm will be collected for biochemical and microbiological analyses. The microhardness surface of the dentine blocks will also be analysed before and after the treatments, for determination of the percentage of surface hardness loss. The biochemical analysis will consist of the determination of fluoride, calcium, and inorganic phosphorus in the fluid and whole biofilm. The microbiological analysis will consist of the counts of total microorganisms, total streptococci, mutans streptococci and lactobacilus. (AU)