The Influence of a Touch-cure System on the Micro-tensile Bond Strength of Self-etch Adhesives to Root Canal Dentin

<p> Purpose: Based on the concept of minimal intervention dentistry and developments in adhesive technology, direct resin composite build-up restorations are increasingly performed for endodontically treated teeth. The adhesive systems and dual-cure resin composites use a touch-cure system which contains a special accelerator to promote chemical polymerization. This accelerator enhances the polymerization of the adhesive in deeper areas where light energy is attenuated, such as post cavities. The purpose of this study was to evaluate the influence of the touch-cure system on the micro-tensile bond strength of selected self-etch adhesive systems to root canal dentin.</p><p> Methods: One two-step self-etch adhesive system, Clearfil SE Bond 2 (SE2) with/without Clearfil DC Activator (DCA), and one one-step self-etch adhesive system, Clearfil Universal Bond QuickER (UBQ), were applied to a root canal post cavity (depth 8 mm, diameter 1.5 mm) according to the manufacturer’s instructions followed by a dual-cure resin composite build-up (Clearfil DC Automix ONE). After immersion of the specimens in water for 24 hours, micro-tensile bond strengths in coronal and apical regions were evaluated. The micro-tensile bond strengths were statistically analyzed using a two-way ANOVA and Student’s t-test with Bonferroni correction (α=0.05).</p><p> Results: Pretesting failures of specimens were not observed in this study. Micro-tensile bond strengths in the apical region were significantly lower than those in the coronal region in all adhesive systems. In the coronal region, a significant difference was seen only between SE2+DCA and UBQ, while there was no significant difference among all tested adhesive systems in the apical region.</p><p> Conclusion: Within the limitations of this study, the effect of the touch-cure system on micro-tensile bond strength to root canal dentin was found in neither the one-step nor the two-step self-etch adhesive system.</p>