Bulk-fill Resin Like Adhesive Cementation of Glass Fiber Posts

Objectives: The objective of this study was to evaluate the adhesive bond strength of glass fiber post cemented with Bulk-fill flow resin in endodontically treated teeth, varying the type of cementation.
Methods: Twenty roots of bovine incisors were selected and randomly divided into 2 groups (n = 10). After the external coating of the roots with molding material, the samples were prepared with Resin cement and Bulk-fill resin flow. The root were sectioned, resulting in two 1.0-mm thick slices from the apical, middle and coronal root regions and submitted to the push-out bond strength test. Data were analyzed using 2way ANOVA and Tukey test. To determine failure mode, two calibrated operators used a stereomicroscope at 40× magnification, with a 2,5D analysis.
Results: Regarding the bond strength, there was not a statistically significant between cementation protocol and the root thirds evaluated (p = 0,536). However, there was a statistically significant difference (p = <0,001) between the cervical, middle and apical thirds since the push out bond strength results obtained, showed significantly higher values in the cervical third when compared to the others.
Conclusions: These results might be explained by the better intimacy between the glass-fiber post and root canal walls at this third. It could also be attributed to the limited light-transmitting ability of fiber posts with increased length of root canals. As for the pattern of failure, within the bulk-fill group, the most prevalent category was “mixed, with resin cement covering partially of the post surface” at the apical third. In the cement resin group, the most frequent category of failure pattern was “adhesive between resin cement and root dentin” at middle third. Regardless of the group evaluated, there was a higher incidence of adhesive failure between resin cement and root dentin and of mixed failures, suggesting that dentin might have influenced the adhesion.