Evaluation of the protective effect of fluoride associated to bioadhesive polymer carbopol in the development of erosive wear

Abstract

The objective of this proposal is to evaluate the protective potential of fluoridated solutions, as well as its association with different bioadhesive film-former polymers on enamel erosive wear development. The proposal is divided in two stages. The first stage will be a in vitro study in which the association of Carbopol 980 polymer to sodium fluoride (NaF) and sodium fluoride with tin chloride (NaF + Sn) will be tested in the presence of acquired pellicle. The remineralizing and protective effect against initial erosion measured by microhardness will be investigated. Polished bovine enamel specimens will be prepared and demineralized with 0.3% citric acid (pH 2.6) for 2 min, (n=15 for each group). The specimens will be immersed in human saliva for 2 hours to allow acquired pellicle formation and then, treatment with experimental solutions for 2 min will be performed [NaF (500 ppm F), NaF + Carbopol 980, NaF + Sn (500 ppm F + 800 ppm Sn), NaF + Sn + Carbopol 980, deionized water (negative control) and comercial mouthrinse (Elmex - positive control]. A new immersion in human saliva (2 h) for remineralization and then new acid challenge will be performed. The Knoop hardness will be measured at different times: baseline, after the first acid challenge, after remineralization, and after second acid challenge. The remineralizing and protective potential will be calculated. Additionally, a new immersion in test solutions will be conducted for the measurement of alkali-soluble fluoride on enamel surface. The second stage will be an in situ study carried out with the experimental solutions that present the greatest protective potential in the previous in vitro study. For this, enamel specimens will be divided into three groups (n = 52): fluoridated solution (positive control), fluoridated solution associated with Carbopol 980, and deionized water (negative control). An in situ model with three stages will be tested. Thirteen volunteers will participate in the study after signing a free and informed consent form. In each phase, volunteers will use a palatal appliance containing 4 specimens each, which will be submitted to a cycle of erosion and remineralization for 5 days, which will consist in oral immersion extra palatal appliance in 0.3% citric acid (pH 2.6) for 2 min, 4x/day at intervals of 1 h with saliva exposure in situ between challenges. The treatment with the solutions will be carried out extra-orally, 2x/day for 1 min, 30 min exposure to saliva in situ after the first and last erosive challenge. The other two specimens will be subjected to erosion/abrasion/remineralization, with abrasion performed 2x/day for 15 sec with the active electric toothbrush, before the daily treatment with the solutions and erosion/remineralization as described. At the end of the experiment, the enamel surface loss (µm) will be evaluated by profilometry. The surface loss data of the specimens for each volunteer at each stage will be submitted to appropriate statistical analysis, considering the significance level of 5%. (AU)