Effect of 4% HF etching intervals on microtensile bond strength of fiber posts to resin composite cores

Abstract

Objective: This study investigated the effect of different etching intervals of 4% HF on the microtensile bond strength of fiber posts to the resin composite cores. Materials and methods: Forty fiber posts were randomly divided into 5 groups. The posts of groups 1-4 were treated with 4% hydrofluoric acid (HF) for 15,30,45 and 60 sec, respectively and silanized for 60 sec. The posts of group 5 were silanized for 60 sec and served as the control group. After surface treatment, two posts from each group were randomly selected to examine the post surface using a SEM. The remaining posts were core built up with Multicore flow using a cylindrical plastic matrix as a mold. The posts and resin composite cores were sectioned into stick specimens and subjected to microtensile bond strength test. The microtensile bond strength was analyzed using One-way ANOVA and Dunnett T 3 at 0.05 significance level. The fracture mode was examined using an SEM and analyzed using Kruskal-Wallis. Results: The microtensile bond strength of all experimental groups was significantly higher than those obtained from the control group (p<0.05). Among the experimental groups, the microtensile bond strength of group 1 was higher than those of groups 3 and 4. The fracture modes of the experimental groups were adhesive and cohesive failure while the posts in the control group revealed adhesive failure. Statistical analysis showed that the experimental groups demonstrated a significant difference from the control group (p<0.05). Conclusion: Etching the fiber posts with 4% HF increased the microtensile bond strength of the fiber posts to the resin composite cores. The etching interval of 15 sec showed significantly higher microtensile bond strength compared to the groups of 45 and 60 sec.