Evaluation of the push-out bond strength of fiber posts in canals treated with conventional or ultrasonic preparation protocols.

Abstract

This in vitro study aimed to compare the effects of conventional and ultrasonic root canal preparation on the adhesion of glass fiber posts to root canal dentin. A total of 20 human maxillary central incisors were instrumented and then filled with gutta percha and sealant using the lateral condensation technique. The teeth were randomly divided into 2 equal groups (n = 10), gutta percha was removed, and canals were prepared using a different protocol for each group: in the conventional group, a Gates-Glidden drill, a Largo drill, and post bur kit were used; in the ultrasonic group, ultrasonic tips were operated in endo mode. Microcomputed tomography was used to confirm complete removal of the filling material, and fiber posts were cemented with self-adhesive resin cement. The apical ends of the roots were discarded, and the remaining portions were transversely sectioned into 3 segments, each 1.5 mm thick. The sections underwent push-out testing to determine bond strength, and the adhesion defects were examined with scanning electron microscopy and stereomicroscopy to determine the failure mode. Data normality was assessed using the Kolmogorov-Smirnov test, followed by analysis of variance with Tukey test for group comparisons and chi-square tests to evaluate any associations regarding failure mode. A 5% significance level was applied. Tukey tests revealed that the conventional group exhibited statistically significant lower push-out bond strengths than the ultrasonic preparation groups across all thirds; no statistically significant differences were noted among the cervical, middle, and apical thirds within the same group. There were no statistically significant differences in failure modes between the preparation groups, and adhesive failure was the most prevalent mode. The ultrasonic method effectively removed gutta percha from canals and enhanced the bond strength of fiber posts.