Proteolytic activity and bond strength of root dentin-cement interfaces produced in the presence of cross-linkers

Abstract

Cross-linkers are natural or synthetically produced substances that improve the number of collagen inter- and intra-molecular bonds as well as the number of inter collagen fibril bonds. Among these substances are glutaraldehyde (GA), protocianidine (PA) and carbodiimide (1-Etil-3-[3-dimetilaminopropil] carbodiimide hydrochloride or EDC). By increasing the strength of collagen fibrils these substances can turn them less susceptible to degradation, improving mechanical properties and stability of adhesive interfaces. However, besides the several studies demonstrating this effect on coronary dentin, there are few studies about the use of cross-linkers on radicular dentin. Therefore, the aim of this study will be to evaluate the effects of three different cross-linkers on the proteolytic activity of radicular dentin and on the dentin bond strength of cement-dentin interface after adhesive cementation of radicular posts. Roots containing one radicular canal will be obtained from sound premolars (n=48). These roots will be endodontically treated and will be randomly distributed in 4 experimental groups (n=12) according to the dentin treatment after etching with phosphoric acid: G1: deionized water (control); G2: 0.5 mol/L EDC; G3: 5% PA and G4: 5% GD. The canal will be prepared for a fiber post cementation with resin cement. After 24 hours, the roots will be sectioned into three 2mm-thick disks (specimens), obtained the cervical, mid and apical region. These specimens will be subjected to push out test and dentin bond strength results will be obtained. Using the same specimens, after the mechanical test, the proteolytic activity of the dentin will be evaluated by the EnzCheck assay by confocal microscopy. Statistical tests will be defined after checking the distribution of the data and homoscedasticity. All tests will be considered at 5% level of significance.