Nanotechnology-based electrochemical approach for effective root canal irrigation

Root canal treatment (RCT) is an endodontic procedure to preserve an infected/inflamed tooth and retain its function. Root canal irrigation is the most crucial step in RCT for cleaning the root canal space. Achieving total disinfection in root canal space is still a significant challenge in dentistry. We developed a novel irrigation approach combining electrochemistry and nanotechnology to eliminate root canal bacteria effectively. Cytotoxicity of the optimized irrigation technique was evaluated using Enterococcus faecalis, and cytocompatibility was evaluated with three different human cell lines (MG63, gingival fibroblast and osteoblasts differentiated from stem cells). A potential of -5 V was applied using an electrochemical set-up to these cells with two different solutions, 0.9 % saline (control) and 5 μg/mL ZnO NPs in 0.9 % saline over various periods (60, 120, and 180 s). E. faecalis biofilms were treated in vitro and viable colony-forming units (CFU) were determined. The morphology of pre- and post-treated cells was examined using SEM and TEM. Morphological changes such as cell membrane rupture or cell lysis were observed in SEM and TEM images of all treatment groups. The optimal ZnO NPs concentration was determined to be 5 μg/mL based on - viability assays of test human cell lines. More than 90 % cell viability was noted with 60s treatment time in all cell lines. Significantly reduced bacterial viability was observed in treatment groups when compared to the non-electrochemically treated groups, indicating effective bacterial eradication.