Comparative Evaluation of Photoactivated Disinfection and an Antioxidant in Modulating the Push-out Bond Strength of AH Plus Sealer: An in vitro Study

Abstract

Background: Photoactivated disinfection (PAD) using Indocyanine Green (ICG) as a photosensitiser activated by a near-infrared diode laser generates reactive oxygen species (ROS) that provide robust antimicrobial activity within the root canal system. However, residual ROS can inhibit polymerisation of resin-based sealers, thereby compromising the sealer–dentine interfacial bond. Ascorbic acid (AA), a potent biocompatible antioxidant, has the potential to neutralise these free radicals and restore dentine redox balance. Objective: The present study aimed to evaluate and compare the push-out bond strength of AH Plus sealer following PAD alone and PAD combined with 10% ascorbic acid application. Materials and Methods: Sixty extracted, single-rooted human maxillary anterior teeth were prepared using ProTaper Gold rotary files and divided into three groups (n = 20 each): Group 1 (Control) – conventional obturation with Gutta-Percha and AH Plus sealer; Group 2 (PAD) – ICG-mediated photoactivated disinfection with an 810-nm diode laser followed by obturation; Group 3 (PAD + AA) – PAD protocol as in Group 2, followed by 10% ascorbic acid irrigation for 10 minutes before obturation. After 7 days of incubation, 1-mm-thick mid-root discs were subjected to push-out bond strength testing using a Universal Testing Machine (UTM). Data were analysed using one-way ANOVA and post hoc Tukey HSD test. Results: Mean push-out bond strength values were as follows: Group 1 – 0.0119 MPa (SD ± 0.00185); Group 2 – 0.0244 MPa (SD ± 0.00676); Group 3 – 0.0503 MPa (SD ± 0.01272). One-way ANOVA revealed statistically significant differences among groups (F = 74.99; p < 0.0001). Post hoc Tukey HSD confirmed significant pairwise differences between all groups (p < 0.05). Conclusion: PAD using ICG and a diode laser significantly improves push-out bond strength of AH Plus sealer compared with conventional obturation. The addition of 10% ascorbic acid following PAD significantly further enhances bond strength by neutralising residual ROS and restoring dentine redox balance. This combined protocol may offer a clinically relevant approach to disinfection while supporting sealer–dentine adhesion under the tested in vitro conditions.