Methodological proposal for evaluation of adhesion of root canal sealers to gutta‐percha

Abstract

To compare the bond strength of an epoxy resin-based sealer and two calcium silicate-based sealers (CSS) to gutta-percha discs using a new method. Round discs of gutta-percha (n=60), measuring 10mm in diameter and 2mm in thickness, were placed on a glass plate and a drop of each sealer (AH Plus, EndoSequence BC Sealer and EndoSeal MTA) was placed on their surface. Another identical disc was placed onto the first one and a standardized weight (0.0981N) applied over them using a specially developed apparatus. Ten samples prepared for each sealer were submitted to a microshear bond strength test accomplished by a specially designed set-up coupled to a universal testing machine. The Kruskal-Wallis test followed by a post hoc procedure was used to compare groups considering the preliminary analysis of the raw data had indicated the nonadherence to a Gaussian distribution (Shapiro-Wilk, p<.05). Alpha error was set at 5%. Overall, no premature failure occurred. All sealers had some degree of adhesiveness to gutta-percha discs but with a significant difference amongst them (Kruskal-Wallis, p=.019). The epoxy resin-based sealer (AH Plus) had significantly higher median shear bond strength values (1.43MPa; 1.40-1.83) compared to EndoSeal MTA (0.53MPa; 0.46-0.73) (p=.021) and EndoSequence BC Sealer (0.45MPa; 0.34-0.46) (p=.023), whilst the lowest median value was observed with EndoSequence BC Sealer (0.45MPa; 0.34-0.46) (p<.05). CSS sealers had weaker bonding to gutta-percha when compared to the epoxy resin-based AH Plus sealer. The proposed methodology is an innovative and reproducible method for testing the bond strength of root canal sealers to gutta-percha.