Effect of 10% sodium ascorbate as an antioxidant on the push-out bond strength of fiber posts following photoactivated disinfection of root canal space: An in vitro study

Abstract Context: The clinical longevity of fiber post restorations depends on the adhesive interface between radicular dentin and resin luting cement. Photoactivated disinfection (PAD) using Indocyanine Green (ICG) and an 810 nm diode laser generates reactive oxygen species (ROS) that may persist in dentinal tubules, impairing resin polymerization and bond strength. Sodium ascorbate may neutralize residual ROS and restore bonding potential. Aims: To evaluate the push-out bond strength and failure modes of fiber posts among three groups: conventional irrigation (control), PAD alone, and PAD followed by 10% sodium ascorbate. Materials and Methods: After institutional ethics approval (approval no. SDMCDS IEC No. 2024/PG/CONS/105), 30 extracted maxillary central incisors meeting predefined inclusion/exclusion criteria were instrumented, obturated and randomly allocated (computer-generated randomization) to three groups (n = 10 each): Group A, conventional sodium hypochlorite/ethylenediaminetetraacetic acid/saline irrigation; Group B, irrigation followed by ICG-mediated PAD; Group C, PAD followed by 10% sodium ascorbate for 10 minutes. Standardized glass fiber posts were luted with RelyX U200 and subjected to push-out testing; failure modes were assessed under stereomicroscopy at 25 × magnification by a single trained evaluator. Statistical Analysis: Data were analyzed using SPSS v25.0 (IBM Corp., Armonk, NY, USA). Normality was assessed with the Shapiro–Wilk test; one-way analysis of variance with Tukey Honestly Significant Difference (HSD) post hoc test was applied (α = 0.05). Results: Group C showed significantly higher push-out bond strength (3.37 ± 0.62 MPa) than Group B (1.41 ± 0.57 MPa) and Group A (0.88 ± 0.45 MPa) (P < 0.001), while Groups A and B were statistically comparable ( P = 0.091). Mixed failure was the predominant mode in Group C (70%), whereas dentin–cement adhesive failure predominated in Group A (50%). Conclusions: 10% sodium ascorbate following PAD significantly improves fiber post push-out bond strength and promotes favorable mixed failure patterns, representing a clinically viable adjunct to postspace protocols involving oxidative disinfection.