Effectiveness Of Different Root Canal Disinfection Protocols On The Reduction Of Bacteria In Large Root Canals

Abstract

Introduction: The aims of this study were to evaluate the effectiveness of disinfection methods and determine the most promising irrigation protocol for regenerative endodontics in teeth with large root canals. Methods: Sterilized root samples with 0.8-mm wide apical foramen (n=94) were prepared from human mandibular premolars. Ninety-two samples were infected with E. faecalis for 21 days and biofilm formation was verified using scanning electron microscopy (n=2). The 90 infected samples were randomly assigned into 9 groups: no intervention (initial), 1.5% NaOCl irrigation (1.5N), 2.5% NaOCl irrigation (2.5N), 1.5N + intermittent passive ultrasonic irrigation (PUI), 1.5N + intermittent canal brushing with Navitip FX (NFX), 1.5N + intermittent XP-endo Finisher (XPF), 1.5N+circumferential filing (CF), 1.5N + 1-min Self-adjusting File (SAF), and 1.5N + mechanical instrumentation using #90‒110 files (MI). Subsequently, the root canal walls were shaved for microbial analysis. The mean colony forming units were determined and analyzed using one-way ANOVA. Results: The mean CFU count was lowest in the MI group (63.5 CFU/mL), followed by the NFX, XPF, SAF, 2.5N, CF, PUI, 1.5N, and initial groups. The remaining bacteria in the 1.5N group was 3.6-fold higher than that of the PUI group; 4‒5-fold higher than that of the 2.5N, CF, and SAF groups; and 22-fold and 36-fold higher than that of the XPF and NFX groups, respectively. The 2.5N and 1.5N groups with adjunctive treatments, excluding the PUI group, had significantly fewer remaining bacteria compared with the 1.5N group (P < .05). Conclusions: Performing various procedures supplemental to 1.5N improved large root canal disinfection. Adjunctive NFX most effectively reduced the number of bacteria without dentin removal.