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Reduction of dual-species biofilm after sonic- or ultrasonic-activated irrigation protocols: A laboratory study

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  • Daniela Hoedke, Charité-Universitätsmedizin Berlin
  • ,
  • Namira Kaulika, Charité-Universitätsmedizin Berlin
  • ,
  • Henrik Dommisch, Charité-Universitätsmedizin Berlin, University of Washington
  • ,
  • Sebastian Schlafer
  • Hagay Shemesh, University of Amsterdam
  • ,
  • Kerstin Bitter, Charité-Universitätsmedizin Berlin

AIM: To evaluate the antibacterial effect of sonic- and ultrasonic-activated irrigation on bacterial reduction of a dual-species biofilm in root canals compared to nonactivated irrigation in a laboratory study.

METHODOLOGY: Two hundred and forty extracted human single-rooted maxillary anterior teeth were divided into two main groups (G, n = 120) according to the initial preparation size of the root canal (G1: size 25, 0.06 taper, G2: size 40, 0.06 taper). Root canals were inoculated with Enterococcus faecalis and Streptococcus oralis. After 5 days, G1 received combined instrumentation (up to size 40, 0.06 taper) and irrigation/activation, whereas G2 received solely irrigation/activation protocols. In both groups, irrigation was performed with sodium hypochlorite (NaOCl 1%) or physiological saline (NaCl 0.9%), using nonactivated syringe irrigation, sonic activation (2 x 30 s) or ultrasonic activation (2 x 30 s). Logarithmic reduction factors (LRFs) of colony-forming units were analysed separately for dentine-adherent and planktonic bacteria immediately after irrigation/activation protocols (time-point 1) or after 5 days of further incubation (time-point 2) by analysis of variance (anova) and post hoc tests (Tukey's HSD, t-test). The significance level was set at 0.05.

RESULTS: In G1 subgroups (combined instrumentation with irrigation/activation), LRFs were significantly affected by the applied irrigation solution (p < .0001), but not by the activation method (p > .05; anova). In G2 subgroups (solely irrigation/activation), both, irrigant solution and activation, significantly affected LRFs (p < .0001, anova). Sonic activation resulted in significantly higher LRFs than ultrasonic activation (p < .0001) which had significantly greater reductions than nonactivated irrigation (p < .05; Tukey's HSD). At T2, strong bacterial regrowth was observed in all groups; however, a significant bacterial reduction was detected for factors instrumentation, irrigant solution and activation (p < .0001; anova). Similar LRFs were found for dentine-adherent and planktonic bacterial cells in all groups (r = 0.91 at T1, r = 0.8 at T2).

CONCLUSIONS: In this laboratory study on extracted maxillary anterior teeth high-frequency sonic activation resulted in a greater bacterial reduction compared to ultrasonic activation in groups receiving solely irrigation/activation protocols; however, irrigation using NaOCl and ultrasonic activation also contributed significantly to bacterial reduction compared to the control groups.

Original languageEnglish
JournalInternational Endodontic Journal
Pages (from-to)2219-2228
Number of pages10
Publication statusPublished - Dec 2021

    Research areas

  • antibacterial effectiveness, nonactivated irrigation, root canal disinfection, sonic activation, ultrasonic activation, BACTERIA, ROOT, AGITATION TECHNIQUES, ENTEROCOCCUS-FAECALIS, TEETH, SODIUM-HYPOCHLORITE, REMOVAL, DENTINAL TUBULES, ANTIBACTERIAL EFFICACY, APICAL PERIODONTITIS

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