Antibiotic-Modified Epoxy Resin Endodontic Sealers: Influence on Polymer-Dentin Interfacial Bond Strength, Microstructural Morphology, and Antimicrobial Performance

Abstract This article assesses the effect of incorporating triple antibiotic medicament (TAM) and amoxicillin into an epoxy resin-based sealer on pushout bond strength (PBS) to root canal dentin and antibacterial efficacy against Enterococcus faecalis. Forty-five extracted human mandibular premolars were selected based on predefined inclusion criteria: single, straight, circular root canals free of calcification. Crowns were removed at the cementoenamel junction, and root canal preparation was completed to an apical size of F3. Specimens were randomly divided into three groups according to the sealer formulation employed (n = 15): group 1 (AH Plus; control), group 2 (AH Plus + amoxicillin), and group 3 (AH Plus + TAM). Antibacterial efficacy, PBS, and failure modes were evaluated via agar diffusion test, universal testing machine, and stereomicroscope, respectively. Sealer-dentin interfacial morphology was examined using scanning electron microscopy. Data were analyzed using one-way analysis of variance and Tukey's post hoc test (p < 0.05). Group 3 (AH Plus + TAM) recorded the largest zone of inhibition (4.993 ± 1.7 mm) and the highest PBS (10.23 ± 0.12 MPa). Group 1 demonstrated the smallest inhibition zone (3.433 ± 0.9 mm) and the lowest PBS (7.25 ± 0.21 MPa). No significant difference in bond strength was observed between groups 1 and 2 (p > 0.05). Under in vitro conditions, TAM incorporation into AH Plus sealer significantly improved both antimicrobial activity against E. faecalis and PBS to root canal dentin.