[Evaluation of modified micro-push-out bond strength of glass fiber posts with chemically treated resin cements].

OBJECTIVE: To evaluate the modified micro-push-out bond strengths of prefabricated glass fiber posts with silaneafter 35% phosphoric acid to resin cements. METHODS: In the study, 40 glass fiber posts were randomly divided into 2 groups (20 posts in each group) for different surface treatments. Group 1, treated with silaneafter 35% phosphoric acid; group 2, no surface treatment (Control group). Then each group was randomly divided into 2 minor groups (modified group and traditional group), with each group with 10. So the four groups were group 1M (phosphoric acid + silane-modified), group 1T (phosphoric acid + silane-traditional), group 2M (control-modified), and group 2T (control-traditional). A modified micro-push-out bond strength test method was used in modified groups. In traditional groups, the 20 extracted human, single-rooted teeth were endodontically treated. Gutta-percha was removed with #1-2 Peeso Reamers (Mani), and the post space of each specimen was enlarged with a standard drill system from the corresponding fiber post system to create a 9 mm post space with at least 4 mm of filling material in the root apex. Following post cementation according to the manufacturer's instructions, the traditional micro-push-out bond strengths were tested using a universal testing machine(0.5 mm/min). Both failure modes were examined with a stereomicroscope. The data of the four groups were statistically analyzed using the one-way ANOVA test(α= 0.05). RESULTS: The bond strengths were (18.85±1.42) MPa for group 1M, (19.39±1.35) MPa for group 1T, (11.26±1.57) MPa for group 2M, and (11.27±1.83) MPa for group 2T. The bond strength of Group 1 was significantly higher than that of group 2(P<0.05), no matter which method was used. The fracture mode 100% in group M was the destruction of the post/resin interface, compared with 65.7% in group T. CONCLUSION: In contrasted to the traditional micro-push-out test, the modified test can evaluate the bond strength of fiber post to resin cement more effectively, and 35% phosphate acid + silane treatment can improve the bonding strength.