INTRODUCTION: This study examined a clinically feasible protocol for improving hydrolytic stability using a 2-step silanization including a nonorganofunctional silane. METHODS: The surfaces of 24 D.T. Light-Posts (Bisco Inc, Schaumburg, IL) were polished and assigned to the following 4 groups: M: 1-step silanization with Monobond-S (MS) (Ivoclar Vivadent, Schaan, Liechtenstein); BM: 2-step silanization with 5% 1,2-bis(triethoxysilyl)ethane and then MS; and HM and HBM: 1-step and 2-step silanization, respectively, after 24% H2O2 etching. Four resin composite cylinders (RelyX Unicem; 3M ESPE, St Paul, MN) were bonded on each surface according to a microshear testing protocol. All bonded samples were stored in water at 37°C for 24 hours, and half of them were then thermocycled 5000 times before microshear testing (n = 12). The failure modes were evaluated under an optical and scanning electron microscope. Water contact angles were measured on the post surfaces before and after silanization to estimate surface hydrophobicity. The results were statistically analyzed using 2-way analysis of variance and the Tukey test. RESULTS: The bond strengths for the BM and HBM groups were significantly higher than the M and HM groups at 5000 thermocycles (P < .05), whereas no significant differences were found between the 4 groups before thermocycling (P > .05). All debonded samples showed some fractured fibers. No significant difference in the hydrophobicity was found between the 1-step and 2-step silanized post surfaces (P > .05). CONCLUSIONS: The 2-step 1,2-bis(triethoxysilyl)ethane/MS treatment has potential as a silanization procedure for enhancing the hydrolytic stability of the fiber post/resin composite interface.
INTRODUCTION: This study examined a clinically feasible protocol for improving hydrolytic stability using a 2-step silanization including a nonorganofunctional silane. METHODS: The surfaces of 24 D.T. Light-Posts (Bisco Inc, Schaumburg, IL) were polished and assigned to the following 4 groups: M: 1-step silanization with Monobond-S (MS) (Ivoclar Vivadent, Schaan, Liechtenstein); BM: 2-step silanization with 5% 1,2-bis(triethoxysilyl)ethane and then MS; and HM and HBM: 1-step and 2-step silanization, respectively, after 24% H2O2 etching. Four resin composite cylinders (RelyX Unicem; 3M ESPE, St Paul, MN) were bonded on each surface according to a microshear testing protocol. All bonded samples were stored in water at 37°C for 24 hours, and half of them were then thermocycled 5000 times before microshear testing (n = 12). The failure modes were evaluated under an optical and scanning electron microscope. Water contact angles were measured on the post surfaces before and after silanization to estimate surface hydrophobicity. The results were statistically analyzed using 2-way analysis of variance and the Tukey test. RESULTS: The bond strengths for the BM and HBM groups were significantly higher than the M and HM groups at 5000 thermocycles (P < .05), whereas no significant differences were found between the 4 groups before thermocycling (P > .05). All debonded samples showed some fractured fibers. No significant difference in the hydrophobicity was found between the 1-step and 2-step silanized post surfaces (P > .05). CONCLUSIONS: The 2-step 1,2-bis(triethoxysilyl)ethane/MS treatment has potential as a silanization procedure for enhancing the hydrolytic stability of the fiber post/resin composite interface.