Bond strength of total-etch dentin adhesive systems on peripheral and central dentinal tissue: A microtensile bond strength test

Abstract

Objective: The purpose of this study was to evaluate the microtensile bond strength (μ TBS) of four total-etch adhesives [Excite (EB), Prime & Bond NT (PBNT), Single Bond (SB), and One Coat Bond (OCB)] by comparing them to five self-etching adhesives (Clearfil SE Bond (CSEB), Xeno III (X III), Prompt L-Pop (PLP), AQ Bond (AQB), and Tyrian/One Step plus (TOSP)] at different dentinal areas. In addition the interface between the adhesive resins and dentin was examined using scanning electron microscopy (SEM). Methods and Materials: Superficial occlusal dentin of extracted human molars was exposed and finished with wet 800-grit silicon carbide paper. A block of composite resin was then bonded to the molar samples with the above adhesives according to the manufacturers' instructions. After 24 hours in water at 37°C, the specimens were sectioned into 1 mm thick slices and divided into two regional subgroups according to their relationship to pulp tissue using visual criteria: pulp center and pulp periphery. The slices were then trimmed for the microtensile bond test and subjected to a tensile force and crosshead speed of 1 mm/min. Two-way analysis of variance was performed for statistical analyses. In addition the bond strengths for nine adhesive systems for each dentinal area were compared using the Post-Hoc test. The resin-dentin interfaces for each adhesive system were observed under a SEM. Results: Mean μ TBS ranged from (25.2 MPa) for TOSP to (48.9 MPa) for PBNT. The bond strengths of total-etch adhesive systems were not significantly different, and were higher than self-etch adhesive systems, except for CSEB (p<0.05). No significant regional difference was observed for all of the nine adhesive systems (p>0.05). SEM observation showed there is not a standard hybridization for adhesive systems. Conclusion: Different dentinal areas may not exhibit as great an influence on bond strengths using new adhesive systems.