Photodynamic Therapy With Resveratrol and an Nd:YAG Laser for Enterococcus faecalis Elimination

Background/Aim: Enterococcus faecalis is the leading cause of endodontic treatment failures. Despite various conventional disinfection approaches, microorganisms often persist in root canals. Photodynamic therapy (PDT) is an adjunct antimicrobial strategy employing a nontoxic photosensitizer (PS) and light source. This study evaluated the antimicrobial effect of PDT using an Nd:YAG laser and resveratrol (RSV) with or without pigment, and confirmed that RSV is nontoxic as a PS. Materials and Methods: We employed laser irradiation at a 3W output power, using RSV and red pigment as the PS, on an E. faecalis bacterial solution. Subsequently, colony -forming units were quantified. The impact of RSV on osteoblasts was measured using an MTT assay. Results: E. faecalis counts declined after laser irradiation. The combined application of laser irradiation with RSV, red pigment, or both showed a reduction compared to no irradiation and control groups without RSV and red pigment. The 50% cytotoxic concentration against osteoblast cells from mice incubated with RSV for 48 h was 162 ,uM. The value with RSV and laser was 201 ,uM and that with RSV and red pigment was 199 ,uM. The value with RSV, laser and red pigment was 357 ,uM. Conclusion: The combination of Nd:YAG laser irradiation and RSV as the PS with pigment was efficacious for E. faecalis elimination without inducing any toxic effects on osteoblasts. This combination holds potential as a root canal irrigation strategy.