The introduction of fibre glass post as retentive resource of endodontically treated teeth was associated with the perspective to fix it intracanal by bonding process. In order to ensure durability, their behavior bonding to the substrate must be well established. The hybrid layer is the adhesive process underlying and has limitations of mechanical and biological order, especially when the demineralized collagen matrix is not completely surrounded by the adhesive system. Proteolytic enzymes intrinsic to the dentin, such as matrix metalloproteinases (MMPs) and cysteine cathepsins (TC) contribute to the degradation of the organic layer. Thus, the use of agents capable of inhibiting it becomes a tool for the preservation of the hybrid layer. Other relevant alternative, is the use of self-etching luting cements, which besides the reduction of operative steps, also minimize the operator's effect. The aim of this study is to evaluate the effect in adhesion of cathepsins of fibre glass post cemented with a resinous luting agent conventionally or associated with chlorhexidine digluconate and associated with a specific inhibitor of cathepsin E-64 with concentrations of 5uM e 10 UM, considering different treatments and root thirds by means of bond strength (RU). A comparison to an additional group luted with self-etching cement will be done as well. Fifty bovine roots will be selected and endodontically treated, before be randomly assigned into following groups according to the luting protocol: U (U200- positive control); ARC (RelyX ARC), ARC+CHX, ARC+ 5E-64 and ARC+10E-64. After 48 hours of luting, the roots will be sliced under irrigation to obtain 1mm-thick slices. Specimens will be subjected to push-out test with a crosshead speed of 0.5mm/min. Data will be analyzed with two-way ANOVA and Tukey's tests (Pd0.05).
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