Effect of endodontic irrigating solutions on the micro push-out bond strength of a fibre glass dowel

Abstract

Purpose: To evaluate the effect of different endodontic irrigating solutions on the micro push-out bond strength of a fiber glass dowel. Material and Methods: Seventy 16-mm long root segments of bovine incisors were prepared and randomly assigned to 7 groups (n=10) according to the type of irrigating solution used prior to the cementation of the intra-radicular fiber glass dowels: G1: 5.25% NaOCl + 17% EDTA; G2: 5.25% NaOCl; G3: 17% EDTA; G4: 2% chlorhexidine gel; G5: 70% alcohol; G6: 11.5% polyacrylic acid; and G7: saline (control). After treatment of intracanal dentin, the glass fibre dowels were cemented with self-adhesive resin cement (RelyX Unicem). Six slices with the thickness of 1.00 ± 0.05 mm were obtained from each tooth at the coronal, middle and apical root thirds (2 slices per third) using a low-speed saw. Micro push-out tests were performed at a crosshead speed of 0.5mm/min and the data (MPa) were analyzed statistically by ANOVA and Tukey's and Dunnett's tests. Results: There were statistically significant differences (p<0.0001) among the irrigating solutions, but no significant difference (p=0.0591) was found among the root thirds. G5 presented the highest bond strength mean of all groups (p<0.0001). The use of 70% alcohol increased the adhesion values by 53% compared to the group control. Conclusion: The use of 70% alcohol increased the bond strength of the fiber glass dowel to the dentin walls. However, the push-out bond strength between the dowel and the root dentin was not affected by the root third (coronal, middle and apical).