Bonding of Dual-cure Composite Resin to Root Canal Dentin

Objectives: This study was performed to evaluate the regional bond strength between root canal dentin and dual-cure resin core material in dependent on different bonding strategies. Methods: Twenty-four extracted premolars were decoronated and their root canals were prepared to a depth of 8 mm and a diameter of 1.5 mm. Five bonding systems were applied to the root canal dentin surfaces: 1) ED Primer II/ Photobond (PB) 2) Clearfil Liner Bond 2V Primer/Bond A (LB:BdA) 3) Clearfil Liner Bond 2V Primer/BondA+B (LB:BdAB) 4) Clearfil SE Bond Primer/Bond (SE) 5) Nano-Bond Primer/Bond (NB). After application of the bonding agent, photoirradiation was performed for 10 or 20 s from a coronal direction. The post spaces were then filled with a dual-cure composite resin (Clearfil DC Core or Build-It FR) and light-cured for 60 s from a coronal direction. After 24 hrs storage, each specimen was serially sliced into 8, 0.6 x 0.6 mm-thick beams for the μTBS test. The failure mode was observed under SEM. The bond strength data were divided into coronal and apical regions and analyzed using ANOVA and Dunnett’s T3 (α = 0.05). Results: Mean (SD) were as follows.  NS and the same superscripts within each table demonstrate no significant differences.

Conclusion: Light-cure bonding resin was effective for application in root canal dentin. Extension of photoirradiation time of the bonding agent was found to have an effect on the bond strength, which was dependent upon the type of bonding agent. Supported by grant from COE Program, FRMDRTB at TMDU.