Effects of solvents on the adhesion of glass fiber posts to root canal dentin: An in vitro study

Purpose: This study compared the effects of solvents (chloroform, orange oil, turpentine, eucalyptol, Endosolv R) and irrigants (5.25% sodium hypochlorite [NaOCl], distilled water) on the adhesion of glass fiber posts luted with dual-cure resin cement to root canal dentin, testing the hypothesis that solvents and NaOCl would impair bond strength. Methods: In this in vitro study, 128 extracted human mandibular premolars were prepared, filled, and retreated using NiTi files with assigned solvents/irrigants. Post spaces were prepared, and glass fiber posts were cemented with dual-cure resin. Push-out bond strength (MPa) was measured on 1-mm-thick root slices using a universal testing machine. Data were analyzed via ANOVA and Tukey tests (p<0.05). Results: Turpentine significantly reduced bond strength compared to control and other solvents (p<0.05). NaOCl also decreased bond strength (p<0.05), while Endosolv R, chloroform, eucalyptol, and orange oil showed values comparable to the control. The highest bond strength was observed with eucalyptol. Conclusion: Turpentine and NaOCl adversely affected glass fiber post adhesion, likely due to solvent penetration or oxygen radical interference. Clinicians should avoid turpentine during retreatment and consider antioxidants with NaOCl. Further research on solvent-dentin interactions is warranted to optimize post-retreatment outcomes. © 2025, Turkish Endodontic Society. All rights reserved.