Push-out Bond Strength of Fiber Posts to Root Canal Dentin Using a One-step Self-etching Adhesive: The Effect of Solvent Removal and Light-curing Methods

Purpose: To evaluate the effect of solvent removal and light-curing methods on the push-out bond strength of fiber posts to root canal dentin using a one-step self-etching adhesive. Materials and Methods: Eighty single-rooted, single-canal human mandibular premolars were used in this study. After removal of the crown, the pulp was extirpated and the post space was prepared. The teeth were divided into two main groups according to the solvent removal method, either using the paper point or the air-drying method. Each of the above main groups was further subdivided into 4 subgroups according to the light-curing method: group 1: both adhesive and resin cement were cured from the top of the post in the same step (cocuring) for 40 s; group 2: the adhesive was light cured for 20 s and the resin cement for 40 s; group 3: the adhesive was light cured for 40 s as was the resin cement; group 4: an intracanal tip was used to cure the adhesive inside the post space for 20 s. In groups 1 to 4, the solvent was evaporated using oil-free compressed air for 5 s from the root surface and excess adhesive was removed from inside the canal using a paper point. In groups 5 to 8, the adhesive and cement were applied and light cured as in groups 1 to 4, except the solvent was evaporated (air dried) from inside the post space using an intra-canal disposable plastic tip attached to the tip of a 3-way syringe. After 24 hours, three 2-mm-thick root slices were obtained from each root. Each slice was subjected to the push-out bond strength test at a crosshead speed of 0.5 mm/min. Factorial analysis (two-way ANOVA) was run to test the effect of solvent evaporation method, light-curing method, and their interactions on bond strength. One-way ANOVA followed by Duncan's Multiple Range Test were used to test the effect of lightcuring method on bond strength within each solvent evaporation method. Student's t-test was performed to compare the effect of solvent evaporation method on bond strength within each light-curing method. Results: Two-way ANOVA revealed that the solvent removal method had a significant effect on the bond strength of fiber post to root canal dentin. Neither the light-curing method nor the interaction between the two independent variables had a significant effect on the push-out bond strength. Conclusions: Only air drying the one-step self-etching adhesive could influence the bond strength of the fiber post to root canal dentin. Keywords: fiber post, self-etching adhesive, solvent removal method, push-out bond strength