Effect of Smear Layer Removal on Bond Strength of Two Different Resin- Based Sealers; an In Vitro Study

Statement of Problem: During root canal preparation, organic pulpal materials, bacteria and blood cells in combination with inorganic dentinal debris accumulate on the canal wall, producing an amorphous irregular smear layer. The effect of smear layer on the bond strength of endodontic sealers is controversial. Objective: The aim of this in vitro study was to evaluate the bond strength of two resin-based root canal sealers to dentin, with or without the presence of smear layer. Materials and Methods: The root canal of Sixty human single rooted teeth were prepared and irrigated by saline, NaOCl, or NaOCl+EDTA. In each group, the root canals were obturated using AH Plus or EndoRez sealers. After 7 days, two horizontal slices of approximately 1.5mm thickness were obtained from the middle third of each root and the pushout bond strength of root canal fillings was assessed using the universal testing machine. Data were analysed using two-way ANOVA and Tukey tests. The significance level was set at p <0.05. Results: Regardless of sealer type, the highest bond strength was observed in group 2 (NaOCl) which was significantly different from those of group 3 (NaOCl+ EDTA) (p =0.003). Regardless of irrigation protocol, AH Plus showed higher bond strength compared to EndoRez (p =0.001). Conclusion: Within the limitations of this study, it was concluded that the experimental sealers bonded better to dentine in presence of smear layer.