Adhesion of an endodontic sealer to dentin and gutta-percha: shear and push-out bond strength measurements and SEM analysis

Abstract

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and guttapercha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Student's t-test (α=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to guttapercha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.

Fracture mechanics analysis of vertical root fracture from condensation of gutta-percha

“…Stress analyses of VRF generally consider a fully connected interface. Motivated by the small shear strength of sealers (Gesi et al, 2005;Teixeira et al, 2009), we use instead a separated interface, as previously done by Rundquist and Versluis (2006) and Versluis et al (2006). The stress transfer at the interface is modeled using a built-in contact algorithm assuming Coulomb's friction law with friction coefficient m. The FEM mesh is refined until the solution converges.…”

An Alternative Adhesive Strategy to Optimize Bonding to Root Dentin

“…The shear-bond strength test has proven to be a feasible and reproducible method that provides homogenous results with considerably low variability in bond strength when compared with the push-out test (22). Therefore, in this study, the shear-bond strength test was used.…”

Influence of root dentin treatment on the push-out bond strength of fibre-reinforced posts

“…6,7 The cementation of an intracanal retainer has a direct influence on the stability and longevity of restorations in endodontically treated teeth. 8 Adhesiveness of the luting agent is influenced by moisture inside the canal, gutta-percha solvents and polymerization shrinkage. 9,10,11 Self-adhesive resin cements have lower contraction stress than conventional resin cements.…”