Investigation of an alternative to enhance the protection of the acquired salivary pellicle against dental erosion by the association of film-forming polymers and sodium fluoride

Abstract

The present study proposes to investigate the effect of solutions containing film-forming polymers, associated or not with sodium fluoride (NaF), in the modification of the acquired salivary pellicle (AP) against dental erosion. This study will be carried out in 3 phases: 2 in vitro and 1 in situ. In step 1, the optimal concentrations and pH of the polymers to be studied will be determined in vitro (Carbopol, Gantrez, sodium linear polyphosphate - LPP, propylene glycol alginate - PGA, and Chitosan). For this, hydroxyapatite crystals will be pre-treated with solutions containing these polymers and their combinations with NaF. Distilled water will be the negative control, and a NaF solution associated with stannous chloride will be the positive control. The pH stabilization method (pH-stat) will be used to determine the hydroxyapatite dissolution. In step 2, these solutions, with the determined concentrations and pH, will be evaluated in vitro for their ability to enhance the protection of the AP against dental erosion, using an erosive cycling model of 5 cycles. Specimens of bovine enamel will be incubated in clarified human saliva for 1 min, treated with the experimental solutions for 1 min, to modify the AP, and will remain for another 28 min in saliva. Then, the erosive challenge will be carried out with 1% citric acid (pH = 3.6) for 3 min. The reflection intensity of the enamel and the percentage of surface microhardness change (%SMC) will be evaluated after the first and second cycles, and surface loss will be evaluated at the end of the cycling, by optical profilometry. The most promising solution will be then selected for phase 3, in situ, that will be compared to the control solutions and NaF, totalizing 4 experimental groups. Fifteen volunteers will use a removable device containing 4 specimens of bovine enamel, which will be subjected to a similar erosive cycling of five days. The %SMC will be evaluated on 2 of the specimens after the second cycle, and surface loss on the other two, by the end of the five cycles. The data obtained will be analyzed with the appropriate statistics tests. (AU)