Tensile bond strengths and adhesive interfaces of ten dentin bonding systems

Tensile bond strength measurements and scanning electron microscopic observations have been performed to evaluate the adhesive properties of new dentin bonding systems. To date, however, it was impossible to compare previously reported data among researchers, because there was no standardization of in vitro test methods. There have also been few reports about the correlation among tensile bond strengths (TBS) and morphological features of the adhesive interfaces of recent systems. Therefore, the purpose of this study was to investigate the relationship between TBS to bovine dentin, following the guidelines documented by the International Organization for Standardization (ISO), and the morphology of resin/dentin interfaces of nine commercially available and one experimental bonding systems. The nine recent bonding systems used in this study showed significantly higher mean TBS (ranging from 25.0 to 14.8 MPa) than did a system (PhB) marketed ten years ago (9.3 MPa). However, morphological features of the resin/dentin interface varied among the systems, and no statistically significant correlation was found between TBS and width of the hybrid layer (p = 0.62). In order to evaluate the quality of the resin/dentin interface, quantitative analyses are needed to clarify the saturation and polymerization of resin in the hybrid layer.