Antimicrobial effectiveness of different irrigation activation techniques on teeth with artificial internal root resorption and contaminated with Enterococcus faecalis: a confocal laser scanning,icroscopy analysis.

This study aimed to compare the antibacterial efficacy of standard needle irrigation (SNI), EDDY, passive ultrasonic irrigation (PUI), photon-induced photoacoustic streaming (PIPS), and shock wave enhanced emission photoacoustic streaming (SWEEPS) activation on the teeth with simulated internal root resorption (IRR) and contaminated with Enterococcus faecalis (E. faecalis) using confocal laser scanning microscopy (CLSM) analyses. A total of 79 human maxillary central incisors with a single canal were selected. The canals were accessed, and then, the roots were split in the bucco-lingual direction. Artificial IRR cavities (depth of 0.8 mm and a diameter of 1.6 mm) were prepared using round burs and 20% nitric acid in the middle region of the root halves. The root halves were reconstructed with cyanoacrylate glue, and the canals were contaminated with a culture of E. faecalis for 30 days. Root canal preparation was performed using the ProTaper Next rotary files up to X5 and 2.5% NaOCl irrigation. Teeth were randomly assigned to five groups according to the irrigation activation method (n = 15): SNI, EDDY, PUI, PIPS, and SWEEPS. The final irrigation procedures were performed using a total of 6 mL of 2.5% NaOCl for each tooth with an activation time of 3 × 30 s. The canals were stained with LIVE/DEAD BacLight dye and analyzed with CLSM to determine the percentages of dead bacteria in the biofilm. Two-way ANOVA and post hoc Tukey tests were used for statistical analysis (P < .05). None of the irrigation activation methods tested provided 100% bacterial elimination. There was no significant difference between the irrigation activation methods tested in terms of the percentage of dead bacteria (P > 0.05). In irrigation activation methods other than PIPS, there was no significant difference in the percentage of dead bacteria between the coronal, middle, and apical regions of the roots (P > 0.05). A higher percentage of dead bacteria was found in the middle region compared to the apical region in the PIPS (P < 0.05). Within the limitations of this study, SII, EDDY, PUI, PIPS, and SWEEPS have a similar antimicrobial effect on the teeth with IRR and contaminated with E. faecalis.