Effect of resin cements on the bond strength of three types of glass fiber post systems to intraradicular dentin.

Abstract

Rehabilitating teeth after root canal treatment often requires the use of glass fiber posts (GFPs) to retain the final restorations, so the choice of resin cement is critical for bond strength (BS) and treatment success.

Aim: The aim of this study was to evaluate the effect of different GFP systems on BS to intraradicular dentin using two dual-curing resin cement types.

Materials and method: Thirty bovine incisors with wide canals were filled endodontically with gutta-percha and epoxy resin sealer. Initially, the canal filling was removed, and 4 mm of the apical seal was left intact. The teeth were divided into three groups according to the GFPs used: AP (anatomical posts - prefabricated GFP (Reforpost #2, Angelus®) relined with composite resin (Filtek Z350, 3M ESPE); SPLENDOR (Splendor SAP, Angelus®), and milled CAD/CAM (FiberCAD, Angelus®). Posts were fixed with conventional (RelyX Ultimate, 3M ESPE) or self-adhesive resin cement (RC) (RelyX U200, 3M ESPE), following the manufacturer's instructions. After 48 h, the roots were sectioned into thirds and subjected to pushout BS testing using a universal testing machine. BS data were analyzed using Wilcoxon and Mann- Whitney U tests. Failure modes were assessed with Fisher's Exact test (α=0.05).

Results: In the apical and middle root sections, BS was similar in the AP and Splendor groups, both of which performed better than the milled CAD/CAM group (p≤0.05). In the cervical section, BS was significantly higher for the anatomical posts than for Splendor and milled CAD/CAM posts. Self-adhesive RC promoted statistically lower BS compared to conventional RC for the milled CAD/CAM post in the cervical and middle thirds (p≤0.05). Self-adhesive RC provided statistically higher bond strength than conventional RC for the anatomical post in the apical third (p≤0.05). No significant difference in failure modes was observed between resin cements and different root sections (p>0.05).

Conclusion: The BS of the GFP system was affected by resin cement type and root section, with composite resin-relined anatomically shaped posts generally performing better.