Comparative Analysis of AH Plus Bond Strength to Root Canal Dentin and Adhesive Interface Quality after Calcium Hydroxide Removal using Different Irrigation Protocols

Abstract

Introduction

To evaluate the push-out bond strength (POBS) of AH Plus sealer to root dentin and the adhesive interface quality after calcium hydroxide (Ca(OH)₂) intracanal dressing removal with different final irrigation protocols.

Method

After root canal instrumentation and irrigation, 40 root canals were filled with Ca(OH)₂ and sealed. After 14 days, the specimens were randomly distributed according to the irrigation protocols for Ca(OH)₂ removal (n = 10): G_H2O (control) - distilled water; G_NaOCl - 1% NaOCl; G_EDTA - 17% EDTA; G_{EDTA + NaOCl} - 17% EDTA + 1% NaOCl. The root canals were filled with AH Plus sealer and gutta-percha. After 7 days, the roots were sectioned into dentin slices and submitted to POBS test and analysis of the adhesive interface under scanning electron microscope. The POBS data were statistically evaluated (analysis of variance and Tukey test). The Kruskal-Wallis and Mann-Whitney tests were used to analyze the adhesive interface (α = 0.05).

Results

G_H2O, G_NaOCl, and G_{EDTA + NaOCl} had similar POBS values, with higher values on the apical third, in comparison with other thirds (P < .05). A homogeneous and free-of-gaps adhesive interface was observed for G_H2O, G_NaOCl, and G_{EDTA + NaOCl}, with difference between G_H2O and G_EDTA (P < .05). G_H2O and G_{EDTA + NaOCl} presented higher sealer tags formation (P < .05).

Conclusion

The final rinse with EDTA for Ca(OH)₂ dressing removal had a negative effect on the POBS of the filling material to root dentin. The use of EDTA followed by NaOCl had results similar to the distilled water, providing uniform and free-of-gaps adhesive interface, and a higher number of sealer tags.