Purpose: To evaluate the push-out bond strengths of prefabricated glass-fiber posts (Beijing Oya Biomaterials) with polydopamine functionalized to root dentin using two different resin cements (Paracore and RelyX Unicem) in different root regions (cervical, middle, and apical).
Materials and methods: Forty extracted human, single-rooted teeth were endodontically treated and a 9-mm post space was prepared in each tooth with post drills provided by the manufacturer. Specimens were then randomly assigned into four groups (n = 10 per group), depending on the adhesive system and post surface treatment used: group IA (Paracore + polydopamine); group IB (Paracore + control); group IIA (RelyX Unicem + polydopamine); group IIB (RelyX Unicem + control). Following post cementation, the specimens were stored in distilled water at 37°C for 7 days. The push-out test was performed using a universal testing machine (0.5 mm/ min), and the failure modes were examined with a stereomicroscope. Data were statistically analyzed using twoway ANOVA (p = 0.05).
Results: Bond strengths (mean ± SD) were: 7.909 ± 3.166 MPa (group IA), 4.675 ± 2.170 MPa (group IB), 8.186 ± 2.766 MPa (group IIA), 4.723 ± 2.084 MPa (group IIB). The bond strength of polydopamine groups was significantly higher than one of the control groups (p < 0.0001). No significant difference was found in the micro push-out bond strengths between the two resin cement groups or the root regions (p > 0.05). Stereomicroscopic analysis showed a higher percentage of adhesive than cohesive failures in all groups.
Conclusion: Surface polydopamine functionalization was confirmed to be a reliable method for improving the bond strength of resin luting agents to fiber posts. The bond strength of Paracore to fiber posts was not significantly different from that of RelyX Unicem, and considering its convenient application, Paracore can be recommended.