Synergistic antibiofilm activity of methylene blue and silver nanoparticle-mediated photothermal therapy against Enterococcus faecalis biofilm

Biofilm formation by Enterococcus faecalis (E. faecalis) in root canals is a significant challenge in endodontic therapy, often leading to persistent infections and treatment failures. This research paper investigates the antibiofilm efficacy of methylene blue mediated photothermal treatment (MB-PTT), as compared to the sole effect of diode laser, PTT, and sodium hypochlorite (NaOCl) on E. faecalis biofilms. 45 maxillary central incisors were decoronated, prepared and infected by E faecalis for seven days. Forty samples were randomly allocated as follows; GI; irrigated with 2.6% NaOCl, GII; irradiated with 660 nm diode laser (250 mW) for 180 s. GIII; Silver nanoparticles (AgNPs) with diode laser application at same parameters (AgNPs-PTT), GIV: accompanied MB and AgNPs-PTT, while 5 samples were kept as control for biofilm formation. The antibiofilm effect was demonstrated both by bacterial colonies counting (CFU/ml) and scanning electron microscope images. The results highlight the potential of all experimental treatment modalities (P < 0.01), However complete absence of detactable bacterial colonies was only evident when MB was coupled with AgNPs-PTT. Accompanied MB with PTT is a promising approach with effective antibiofilm activity against E. faecalis biofilms.