The adhesion between fibre posts and composite resin cores: the evaluation of microtensile bond strength following various surface chemical treatments to posts

Aim To evaluate the influence of various surface treatments to fibre posts on the microtensile bond strength with different composite resins. Methodology A total of 110 fibre posts were randomly divided into five groups, according to the surface pre-treatment performed. Group 1: immersion in 24% H2O2 for 10 min and silanization for 60 s; group 2: immersion in 10% H2O2 for 20 min and silanization for 60 s; group 3: immersion in 4% hydrofluoric acid gel for 60 s and silanization for 60 s; group 4: silanization of the post surface for 60 s and application of the bonding agent G-Bond; group 5: silanization of the post surface for 60 s (control group). After treatment, two posts were randomly selected from each group to evaluate the morphological aspect of the post surface with scanning electron microscopy. The remaining posts in each group were divided into five subgroups of five posts each, which differed in the type of composite resin used for the core build-up. Post-core strength were calculated and the differences among experimental groups were analysed with two-way ANOVA and the Tukey test (alpha = 0.05). Results The post-core strengths achieved in groups 1 and 2 were significantly higher (P < 0.05), than those of groups 3, 4 and 5. The post-core strength in the control group was significantly lower (P < 0.05) than all other groups. Conclusions Hydrogen peroxide and hydrofluoric acid both modified the surface morphology of fibre posts and with silane, significantly enhanced the interfacial strength between them and core materials.