Model-dependent antimicrobial performance of endodontic sealers: An in vitro comparison of planktonic and multispecies biofilm assays.

Abstract

Objectives: To evaluate the antibacterial effects of tricalcium silicate cement-based sealers and epoxy resin-based sealer with planktonic versus multispecies biofilm assays at 0, 28, and 90 days. The physicochemical properties of the tested sealers were also assessed.

Methods: Four root canal sealers were investigated: AH Plus Jet and AH Plus Bioceramic (Dentsply Sirona, Tulsa, OK, USA), BioRoot RCS, and BioRoot Flow (Septodont, Saint-Maur-des-Fossés, France). Film thickness, flow, radiopacity and solubility were assessed in accordance with ISO 6876:2012. Hydration characteristics and functional groups were analysed using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Antibacterial activity was evaluated using a direct contact test (DCT) against planktonically grown Enterococcus faecalis and Fusobacterium nucleatum, as well as a multispecies biofilm assay incorporating E. faecalis, F. nucleatum, Streptococcus oralis, and Porphyromonas gingivalis. Bacterial viability was determined on material aged for 0, 28, and 90 days. Morphological evaluation of sealers and biofilms was performed using scanning electron microscopy (SEM). Data were analysed using one-way and two-way ANOVA with Tukey post hoc tests.

Results: All sealers met the ISO 6876:2012 requirements for setting time, flow, film thickness and radiopacity, but the hydraulic sealers exhibited higher solubility than AH Plus (P < 0.001). Progressive Ca (OH)₂ formation, particularly in BioRoot RCS, was confirmed by XRD and FT-IR over time. In planktonic assays, tricalcium silicate sealers demonstrated significant antibacterial activity against both bacterial species (P < 0.001), whereas AH Plus resin- based sealer showed limited inhibition. However, the multispecies biofilm assay revealed greater bacterial tolerance and reduced antimicrobial effects for all sealers.

Conclusion: Tricalcium silicate sealers exhibited strong antibacterial activity against planktonic bacteria, however, their antimicrobial effects were diminished against multispecies biofilms. These findings highlight the importance of using biofilm-based assays to evaluate the clinically relevant antimicrobial performance of endodontic sealers, aligning laboratory evaluations with the clinical challenges encountered in root canal infections.