Application of on-demand aqueous chlorine dioxide solution for non-surgical root canal treatment

Oral biofilms contribute to apical periodontitis, a major cause of tooth loss. This study evaluated the potential of an on-demand aqueous chlorine dioxide solution, "matching transformation system" (MA-T), as a safer alternative to conventional root canal irrigants. The antibacterial activity of MA-T was assessed against mono-species biofilms (Enterococcus faecalis, Parvimonas micra, Fusobacterium nucleatum), polymicrobial biofilms derived from human supragingival plaque, and an in vitro infected root canal model using E. faecalis. Antibacterial efficacy was evaluated using viable cell counting and confocal laser scanning microscopy (CLSM) to quantify the reduction in bacterial load. Biofilm mass was assessed by crystal violet (CV) staining. Cytotoxicity was evaluated by treating rat osteoblasts and human periodontal ligament fibroblasts with MA-T or NaOCl, followed by assessment of ATP levels and morphological integrity. MA-T eradicated planktonic bacteria, inhibited biofilm formation, and significantly reduced viable bacteria in established biofilms without affecting the total amount of biofilm biomass time-dependently. The infected root canal model showed a substantial decrease in bacterial load. Compared with NaOCl, MA-T-treated cells retained higher ATP levels and normal morphology. MA-T could be a promising root canal irrigant offering effective disinfection and superior biocompatibility, making it a potential alternative to traditional root canal irrigants as NaOCl.