Evaluation of bacterial reduction by contemporary irrigation activation methods against Enterococcus faecalis biofilm...

The aim of this study was to evaluate the bacterial reduction achieved under in vitro conditions by different irrigation activation methods applied with sterile physiological saline solution in an Enterococcus faecalis root canal biofilm model. Seventy single-rooted and single-canal mandibular premolar teeth were divided into seven groups (n = 10): positive and negative control groups and five experimental groups (Standard needle irrigation-SNI, EDDY, passive ultrasonic irrigation-PUI, XP-Endo Finisher, Erbium: Yttrium-Aluminum-Garnet-Er: YAG laser). On the 21st day of biofilm formation, initial samples (S1) were obtained; they were cultured on blood agar, quantified as CFU/mL, and analyzed using scanning electron microscopy. Following irrigation activation, second samples (S2) were obtained and evaluated using the same procedure. The data were analyzed using SPSS 23 software. Since the assumptions of parametric tests were not met, the Kruskal-Wallis and Bonferroni-adjusted Mann-Whitney U tests were used for intergroup comparisons, and the Wilcoxon test was used for pre- and post-procedural comparisons (p < 0.05). No significant difference was found among the groups in terms of S1 values (p = 0.272). In all experimental groups, a significant reduction in bacterial counts was detected as a result of the comparison of S1 and S2 values (p < 0.005). A significant difference was determined among the groups with respect to S2 values (p < 0.001). The EDDY group exhibited the lowest mean value and was found to be significantly different from all other groups (p < 0.001). No significant difference was observed among the PUI, XP-Endo Finisher, and Er: YAG laser groups (p > 0.001); however, each of these groups demonstrated significantly lower bacterial counts compared to the SNI group (p < 0.001). In conclusion, all evaluated methods provided a significant reduction in bacterial counts; however, EDDY was determined to be the most effective method. Further studies are required to evaluate its clinical effectiveness.