Effect of Bonding Agents on Bond Strength of Prosthodontic Composite

Objectives: The object of the current study was to evaluate the repair bond strengths between layers of a highly loaded prosthodontic composite material when combined with silane primers and unfilled resin bonding agents. Methods: Disk specimens were prepared with the dentin portion of the composite material (Estenia, DA3, Kuraray) and abraded with a silicon-carbide rotary cutting instrument. The specimens were conditioned with varying combinations of silane primer (Clearfil Porcelain Bond Activator, Clearfil Porcelain Bond Activator+Clearfil Mega Bond-Primer, and unprimed) and bonding agent (Modeling Liquid, Stain Diluent, and no-bonding agent). After placing the enamel portion of the same brand of composite material (Estenia, E1) on each surface of the dentin material, the specimens were light-exposed, and either wet- or dry-stored at 37ûC for 24 hours. Shear bond strengths were determined and the results were analyzed by analysis of variances (ANOVA) and post-hoc tests (P < 0.05). Results: Average bond strength varied from 49.6 to 31.3 MPa in the dry-stored groups and from 48.3 to 31.0 MPa in the wet-stored groups. Of the combinations tested, the unprimed and Modeling Liquid and the Clearfil Porcelain Bond Activator+ Clearfil Mega Bond-Primer and Modeling Liquid showed the greatest bond strengths for dry and wet conditions, respectively. The groups with no bonding agent generally resulted in a poor repair bond strength. Conclusions: The use of specific combinations of silane primer and bonding agent is recommended for achieving reliable bond strength between layers of Estenia composite.