Investigations into in situ Enterococcus faecalis biofilm removal by passive and active sodium hypochlorite irrigation delivered into the lateral canal of a simulated root canal model

Abstract Aim To investigate in situ Enterococcus faecalis biofilm removal from the lateral canal of a simulated root canal system using passive or active irrigation protocols. Methodology Root canal models ( n = 43) were manufactured from transparent resin materials using 3D printing. Each canal was created with an 18 mm length, apical size 30, a .06 taper and a lateral canal of 3 mm length, with 0.3 mm diameter. Biofilms were grown in the lateral canal and apical 3 mm of the main canal for 10 days. Three models from each group were examined for residual biofilm using SEM. The other forty models were divided into four groups ( n = 10). The models were observed under a fluorescence microscope. Following 60 s of 9 mL of 2.5% Na OC l irrigation using syringe and needle, the irrigant was either left stagnant in the canal or activated using gutta‐percha, sonic or ultrasonic methods for 30 s. Images were then captured every second using an external camera. The residual biofilm percentages were measured using image analysis software. The data were analysed using generalized linear mixed models. A significance level of 0.05 was used throughout. Results The greatest level of biofilm removal was obtained with ultrasonic agitation (66.76%) followed by sonic (45.49%), manual agitation (43.97%) and passive irrigation groups (38.67%), respectively. The differences were significant between the residual biofilm in the passive irrigation and both sonic and ultrasonic groups ( P = 0.001). Conclusion Agitation resulted in better penetration of 2.5% Na OC l into the lateral canal of an artificial root canal model. Ultrasonic agitation of Na OC l improved the removal of biofilm.