Adhesion of endodontic sealers to dentin and gutta- percha offers clues into their interaction with the wall of the root canal and the filling material. In this in vitro study, four classes of endodontic sealers (Kerr, a ZOE-based sealer; Sealapex, a calcium hydroxide-based sealer; AH 26, an epoxy resinbased system; and Ketac-Endo, a glass-ionomer based sealer) were compared for their ability to bond to dentin or gutta-percha. Flat coronal dentin or gutta-percha surfaces were created by using a diamond-impregnated saw blade. Aluminum cylinders (ca. 5-mm diameter) were stabilized on the substrates with small amounts of wax and then filled with one of the sealers. After setting in 100% humidity for 24 h, their tensile bond strengths were measured. Controls were the unfilled cylinders stabilized with wax. The bond strengths and modes of failure were measured. The results were statistically analyzed by using a two-way ANOVA (materials versus substrates) and Student-Newman- Keuls test at α = 0.05. The results indicated that sealant bond strengths to dentin (from lowest to highest mean ± SD, n = 10) were: Kerr 0.13 ± 0.02; Sealapex 0.30 ± 0.08; Ketac-Endo 0.80 ± 0.24; AH 26 2.06 ± 0.53 MPa. The latter two were significantly different (p < 0.05) from the first two sealers and from themselves. The sealant bond strength to gutta-percha (from lowest to highest mean ± SD, n = 10) were: Ketac- Endo 0.19 ± 0.01; Sealapex 0.22 ± 0.01; Kerr 1.07 ± 0.19; AH 26 2.93 ± 0.29 MPa. AH 26 gave the significantly highest bonds to gutta-percha.
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