Comparative Evaluation of Conventional Syringe Irrigation, Manual Dynamic Agitation, Sonic Activation, Negative-pressure Irrigation and Ultrasonic Activation for the Elimination of Enterococcus Faecalis from Infected Root Canals: An in Vitro Study
DOI:
https://doi.org/10.48165/ajm.2026.9.02.13Keywords:
Enterococcus faecalis, root canal irrigation, ultrasonic activation, sonic activation, negative-pressure irrigationAbstract
Background: Microorganisms persisting within anatomically inaccessible areas of the root canal system can compromise endodontic treatment. Enterococcus faecalis is frequently investigated because of its ability to penetrate dentinal tubules, survive adverse conditions and persist after chemomechanical preparation. Irrigant activation may improve antibacterial effectiveness by promoting irrigant penetration and fluid exchange. Aim: To compare the effectiveness of conventional syringe irrigation, manual dynamic agitation, sonic activation, negative-pressure irrigation and ultrasonic activation in reducing E. faecalis from experimentally infected root canals. Materials and Methods: Sixty-five extracted human mandibular first premolars with single canals and closed apices were prepared to ProTaper F2, sterilised and inoculated with E. faecalis. After seven days of incubation, the specimens were randomly assigned to five groups (n=13): conventional syringe irrigation, manual dynamic agitation, sonic activation, negative-pressure irrigation and ultrasonic activation. Following irrigation, microbiological samples were collected using sterile paper points, serially diluted and cultured on blood agar. Colony-forming units per millilitre (CFU/mL) were calculated. Data were analysed using one-way analysis of variance and post-hoc pairwise comparisons at a significance level of 5%. Results: The representative baseline bacterial count was 1559.50±56.77 CFU/mL. Mean residual counts were 761.31±580.28 CFU/mL with conventional irrigation, 532.15±302.62 CFU/mL with manual dynamic agitation, 368.77±246.30 CFU/mL with sonic activation, 90.92±72.01 CFU/mL with negative-pressure irrigation and 17.77±18.63 CFU/mL with ultrasonic activation. The overall difference was statistically significant (F=12.49; pp<0.001). Ultrasonic activation produced the greatest reduction, followed by negative-pressure irrigation. Conclusion: Ultrasonic activation and negative-pressure irrigation achieved greater bacterial reduction than the other tested methods. Nevertheless, no technique consistently rendered every root canal culture-negative.
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