Effects of different irrigation agents on the bond strength of fiber posts to dentin structure

This study aims to investigate the push-out bond strengths following the cementation of fiber-reinforced posts, after passive ultrasonic activation of the post space using EDTA, MTAD, Dual Rinse, and SmearOFF final rinsing solutions, as well as to identify the types of bond failures that occur. Materials and Methods: In this study, 60 human lower premolars extracted due to periodontal reasons were used. To standardize the root lengths, the coronal portions of the teeth were removed to a distance of 14 mm from the apex using a diamond fissure bur with water cooling. The working length of the teeth was set using a #15 K-file, ensuring it was 1 mm shorter than the major apical foramen. The root canals were enlarged using M25 and M40 T-Endo MUST NiTi file systems and an Ai motor. After completing the chemomechanical shaping, the root canals were irrigated with EDTA and NaOCl, and then filled using a bioceramic-based canal sealer with a single-cone technique, leaving 5 mm of canal filling at the apices. Post spaces measuring 9 mm in length were prepared using a fiber post drill set, ensuring 5 mm of canal filling remained, and the 60 samples were randomly divided into four groups (EDTA; MTAD; Dual Rinse; SmearOFF) (n=15). Intermittent passive ultrasonic activation protocols were applied to the final rinsing solutions. Fiber-reinforced posts with a diameter of 1.3 mm were cemented into the post spaces using the self-adhesive resin cement Panavia SA Cement Universal. The samples were embedded in cold acrylic using cylindrical plastic molds to obtain cross-sections. Three sequential cross-sections, each 2.0 ± 0.1 mm thick, were obtained using a precision cutting device. Push-out tests and failure analyses were performed on the samples. The data were analyzed using IBM SPSS V23 and JAMOVI 2.3.28. The normal distribution of the data was assessed using the Shapiro-Wilk test. A two-way Robust ANOVA test from the Walrus package was employed to compare bond strengths based on irrigation solutions and regions, with Bonferroni correction applied for multiple comparisons. Results: No statistically significant difference was found based on the final rinsing solution applied (p>0.050). Although there was no statistical difference in terms of the main effect of the solution, the bond strength was highest in the EDTA group and lowest in the Dual Rinse group. Bond strength values by section were observed in the order of coronal>middle>apical. No inter-group differences were found among EDTA, MTAD, and SmearOFF (p>0.050), while in the Dual Rinse group, the bond strength in the coronal area was significantly higher than that in the apical area (p<0.050). Bond failures were predominantly of the adhesive type, while cohesive failures were observed at the lowest level. Conclusion: EDTA, Dual Rinse, MTAD, and SmearOFF solutions have demonstrated comparable effects when utilized for post-space irrigation.