Adhesive Durability Inside the Root Canal Using Self-adhesive Resin Cements for Luting Fiber Posts

Objectives: The aim of the study was to investigate the effects of various self-adhesive resin cements on the push-out bond strengths and nanoleakage expression at the luting interfaces of fiber posts immediately and after one year of aging. Methods and Materials: One hundred forty-four extracted human anterior teeth were endodontically treated. After post space preparation, fiber posts were luted using five commercially available self-adhesive resin (SAR) cements and a core build-up material applied with a self-etch adhesive (BF: Bifix SE/Rebilda Post, VOCO; CSA: Clearfil SA Cement/Rely X Fiber Post, 3M ESPE; RX: RelyX Unicem 2/Rely X Fiber Post, 3M ESPE; SPC: Speed Cem/FRC Postec, Ivoclar Vivadent; SMC: Smart Cem/X Post, Dentsply; RB: Rebilda DC-Futur-abond/Rebilda Post; n=22). For each group, half of the specimens were subjected to thermocycling (TC) (5 degrees C-55 degrees C, 10,000 cycles) and stored humid for one year at 37 degrees C. Push-out bond strength data of six slices (thickness 1 mm) per root and nanoleakage expression of representative specimens were evaluated after 24 hours (baseline) and after TC and storage for one year (aging), respectively. Results: Bond strength differed significantly among resin cements (p<0.0005) and the location inside the root canal (p<0.0005), but not by aging (p =0.390; repeated-measures analysis of variance). SMC (14.6 +/- 5.8 MPa) and RX (14.1 +/- 6.8 MPa) revealed significantly higher bond strength compared to BF (10.6 +/- 5.4 MPa) and RB (10.0 +/- 4.6 MPa) but differed not significantly from SPC (12.8 +/- 4.8) MPa; CSA (6.1 +/- 4.6 MPa) revealed significantly lower bond strength compared to all other investigated materials (p<0.05; Tukey Honestly Significantly Different). Qualitative nanoleakage analysis revealed more silver deposits at the interface in all groups after aging. For CSA, a large amount of silver deposits inside the cement was also observed at baseline and after aging. Conclusions: Fiber post luting using SAR cements demonstrated reliable bond strengths. Product-specific differences and initial degradation effects could be demonstrated.