The microtensile bond strengths of four resin core materials and fiber posts and their micromorphologic characteristics

Objective: To evaluate the morphologies of D.T. Light-Post (LP), JFP-II quartz (JQ), and JFP-II glass (JG) fiber posts and their microtensile bond strengths to light- or dual-cured resin core materials. Method and Materials: The resin core materials that were used for the core buildup included three dual-cure core materials (Clearfil DC, Rebilda DC, and Luxacore Z) and a light-cured core material (Z100). The microtensile bond strength of each group was tested, and the morphology of each post and fractured surface was evaluated using scanning electron microscopy. Two-way ANOVA and Tukey or Dunnett T3 tests were used for statistical analyses. Results: LP exhibited wider fibers and less matrix than the JFP-II posts, and JQ exhibited a similar surface texture to JG. The bond strength of the JQ group was significantly less than that of the other groups, but for each of the resin core materials that were used in this study, there were no statistical differences between JQ and JG. The results also showed that the microtensile bond strengths of the Luxacore Z/LP and Z100/JG groups were significantly higher than those of the other groups. Cohesive failure was the exclusive mode of failure in the Z100 group, and the other fractured surfaces exhibited adhesive failure. Conclusion: The bonding between fiber posts and resin core materials is affected by the fiber type, but the type of dual-cure resin has no effect on the post and core bonds for any of the three posts used in this study. Keywords: bond strength, fiber post, microtensile test, resin material