title: 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 gutta-percha, 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 (alpha=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 gutta-percha 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 skillful 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.
authors.affiliation: Department of Stomatology, Dental School, University of Santa Catarina, Florianópolis, SC, Brazil.
authors.forename: Cleonice Silveira
authors.initials: CS
authors.lastname: Teixeira
authors.forename: Edson
authors.initials: E
authors.lastname: Alfredo
authors.forename: Luis Henrique de Camargo
authors.initials: LH
authors.lastname: Thomé
authors.forename: Ricardo
authors.initials: R
authors.lastname: Gariba-Silva
authors.forename: Yara T Correa
authors.initials: YT
authors.lastname: Silva-Sousa
authors.forename: Manoel Damião
authors.initials: MD
authors.lastname: Sousa-Neto
mesh_terms: D000268:Adhesiveness; D001840:Dental Bonding; D003799:Dental Stress Analysis / Q000379:methods; D003804:Dentin; D017220:Dentin-Bonding Agents; D004853:Epoxy Resins; D006171:Gutta-Percha; D006801:Humans; D008855:Microscopy, Electron, Scanning; D015203:Reproducibility of Results; D012387:Root Canal Filling Materials; D033081:Shear Strength; D013314:Stress, Mechanical
chemical_list: D017220:Dentin-Bonding Agents; D004853:Epoxy Resins; D012387:Root Canal Filling Materials; C534916:epoxy resin-based root canal sealer; D006171:Gutta-Percha