Effectiveness of low concentration of sodium hypochlorite activated by Er,Cr:YSGG laser against Enterococcus faecalis biofilm

Lasers Med Sci. 2019 Mar;34(2):247-254. doi: 10.1007/s10103-018-2578-6. Epub 2018 Jul 6.

Abstract

Bacteria living in biofilms exhibit altered growth phenotypes, while the biofilm provides benefits, the foremost of which is a certain protection against both immune system and killing effect by antimicrobials. Laser-activated irrigation (LAI) and passive ultrasonic irrigation (PUI) have been proposed as alternative methods for cleaning and disinfecting the root canal, as an adjuvant to conventional chemo-mechanical preparation in order to improve debridement and disinfection. Nevertheless, the potential antibacterial effect of LAI using 0.5% of sodium hypochlorite (NaOCl) has received little attention. Glass Pasteur pipettes were used to mimic single-tooth root canal and to build Enterococcus faecalis biofilm. Several irrigants and treatments were assayed for 60 s including (I) Saline, (II) NaOCl 0.5%, (III) NaOCl 5%, (IV) Er,Cr:YSGG, (V) Saline + LAI, (VI) NaOCl 0.5% + LAI, (VII) Saline + PUI, and (VIII) NaOCl 0.5% + PUI. Bacterial reduction was measured by counting the colony-forming units (CFUs). Additionally, AFM visualization and measurement of nano-roughness parameters were used to evaluate LAI effect on bacteria. NaOCl 5% unpowered and NaOCl 0.5% + LAI were capable of eliminating all bacteria, whereas non-activated saline solution and NaOCl 0.5% failed to eliminate E. faecalis. Lower efficiencies were achieved by PUI. Surface analysis by AFM revealed apparent alterations in NaOCl + LAI-treated cells. The Er,Cr:YSGG laser-activated irrigation (LAI) increased the bactericidal efficiency of 0.5% NaOCl against E. faecalis biofilm.

Keywords: Cavitation; Enterococcus faecalis; Er,Cr:YSGG laser; Laser-activated irrigation; Root canal disinfection; Sodium hypochlorite.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Biofilms / drug effects*
  • Dental Pulp Cavity / microbiology
  • Enterococcus faecalis / drug effects
  • Enterococcus faecalis / physiology*
  • Humans
  • Imaging, Three-Dimensional
  • Lasers, Solid-State*
  • Root Canal Irrigants / pharmacology
  • Sodium Hypochlorite / pharmacology*
  • Ultrasonics

Substances

  • Anti-Bacterial Agents
  • Root Canal Irrigants
  • Sodium Hypochlorite