PURPOSE: The objective of this study was to verify the influence of resin cement polymerization mode and early cyclic loading on the bond strength of porcelain-dentin specimens. MATERIALS AND METHODS: Two cementation systems, Choice/One-Step and RelyX ARC/Single Bond, were tested. Porcelain truncated cones were bonded into cavities prepared in sections of bovine root dentin. Each system was tested with the resin cement in dual-cure and self-cure mode (with and without photoactivation, respectively). Half of the specimens were load cycled 15 minutes after cement mixing (60 N, 20 times). The other half were not submitted to mechanical loading (control). After 24-hour storage in distilled water (37 degrees C), the extrusion shear test was performed. Data were analyzed by three-way ANOVA. RESULTS: With both systems, some specimens built with the cement in self-cure mode debonded during cyclic loading (RelyX ARC/Single Bond 47%; Choice/One-Step 13%). No significant system effects were detected. Mean bond strength under the dual-cure mode (13.4 MPa, SD 3.6) was significantly higher than the corresponding mean for the self-cured specimens (5.7 MPa, SD 2.6). No reduction in bond strength was observed for the specimens that survived the early cyclic loading. CONCLUSION: Resin cements in dual-cure mode presented higher bond strengths than self-cured materials. Early load cycling caused debonding of some self-cured specimens. However, the bond strength of the survivor specimens was not affected by load cycling.
PURPOSE: The objective of this study was to verify the influence of resin cement polymerization mode and early cyclic loading on the bond strength of porcelain-dentin specimens. MATERIALS AND METHODS: Two cementation systems, Choice/One-Step and RelyX ARC/Single Bond, were tested. Porcelain truncated cones were bonded into cavities prepared in sections of bovine root dentin. Each system was tested with the resin cement in dual-cure and self-cure mode (with and without photoactivation, respectively). Half of the specimens were load cycled 15 minutes after cement mixing (60 N, 20 times). The other half were not submitted to mechanical loading (control). After 24-hour storage in distilled water (37 degrees C), the extrusion shear test was performed. Data were analyzed by three-way ANOVA. RESULTS: With both systems, some specimens built with the cement in self-cure mode debonded during cyclic loading (RelyX ARC/Single Bond 47%; Choice/One-Step 13%). No significant system effects were detected. Mean bond strength under the dual-cure mode (13.4 MPa, SD 3.6) was significantly higher than the corresponding mean for the self-cured specimens (5.7 MPa, SD 2.6). No reduction in bond strength was observed for the specimens that survived the early cyclic loading. CONCLUSION: Resin cements in dual-cure mode presented higher bond strengths than self-cured materials. Early load cycling caused debonding of some self-cured specimens. However, the bond strength of the survivor specimens was not affected by load cycling.