Effect of Root Canal Irrigants on Fiber Post Bonding Using Self-adhesive Composite Cements

Purpose: To evaluate the effect of different irrigation solutions on the bonding of self-adhesive composite cements to the root canal during fiber-post cementation. Materials and Methods: One hundred twenty single-rooted human teeth were endodontically treated. The post spaces were prepared and specimens were randomly divided into ten groups, according to the combination of the factors: post space irrigation (distilled water, 2.5% NaOCl, 17% EDTA, 26% polyacrylic acid, and 17% EDTA + 2.5% NaOCl) and self-adhesive composite cement (RelyX U200 [3M Oral Care] and Multilink Speed [Ivoclar Vivadent]). The proportion of open dentinal tubules was evaluated by SEM. After fiber post cementation, six slices were obtained from each root (coronal, middle, and apical thirds) for evaluation of push-out bond strength (BS), nanoleakage (NL), and Vickers microhardness (VHN) of the composite cement. Data from open dentinal tubules were submitted to Kruskal-Wallis and Student-Newman-Keuls tests (α = 0.05). Data from BS, NL, and VHN were evaluated by two-way ANOVA and Tukey's test (α = 0.05). Results: Irrigation with EDTA, polyacrylic acid, and EDTA + NaOCl increased the proportion of open dentinal tubules. For RelyX U200, NaOCl, distilled water and EDTA resulted in the highest BS and VHN values, while for Multi- link Speed, these values were higher only for distilled water. Both composite cements presented lower BS and VHN with polyacrylic acid. NL did not differ between experimental groups (p > 0.05). Conclusion: For both composite cements tested, distilled water showed better results in push-out and microhardness tests. Keywords: adhesive cementation, bond strength, endodontic fiber posts, indentation, nanoleakage, self-adhesive luting