Influence of the final irrigation solution on the push-out bond strength of calcium silicate-based, epoxy resin-based and silicone-based endodontic sealers

The aim was to evaluate the influence of different irrigation solutions on the push-out bond strength (POBS) of three different sealers (AH Plus, BioRoot RCS, GuttaFlow2). Root canals of 180 single-rooted human teeth were instrumented with F360 up to size 45.04. All canals were irrigated with 5ml NaOCl 3% and 5ml EDTA 17%. The canals were finally irrigated with either 5ml NaOCl 3%, CHX 2%, EDTA 17%, citric acid 20% or NaCl 0.9% (n=36) with a contact time of 5min and obturated using matching gutta-percha cones according to the single-cone technique in combination with one of the sealers (n=12). After 8weeks of incubation, the roots were embedded in resin. Two slices of 1mm thickness were obtained representing the middle third of the root. Dislodgement resistance was measured and POBS was calculated. Specimens were examined under 4x magnification to determine the mode of bond failure. Statistical analysis was performed using two-way ANOVA and Student-Newman-Keuls test for POBS and Chi-square test for the mode of failure. POBS was significantly affected by the factor sealer (P<0.001) and by the interaction sealer/irrigation solution (P<0.01). AH Plus revealed significantly higher POBS than BioRoot RCS and GuttaFlow2 (P<0.05). The POBS of GutttaFlow2 was not affected by the irrigation protocol (P>0.05). The POBS of AH Plus was positively influenced by EDTA and NaOCl. EDTA had a negative effect on the POBS of BioRoot RCS. The POBS of GuttaFlow2 was not influenced by the irrigation solutions.