title: Effectiveness of EDTA and Modified Salt Solution to Detach and Kill Cells from Enterococcus faecalis Biofilm.
abstract: BACKGROUND
  Disruption of the matrix of endodontic biofilms will aid in their removal from a root canal. Therefore, the aim of this study was to investigate the efficacy of EDTA and a modified salt solution (MSS) to detach bacteria from biofilms.
  
  
  METHODS
  Forty-eight-hour-old Enterococcus faecalis biofilms were grown on glass coverslips and then treated for 1 hour by immersion in 17% EDTA or MSS. Phosphate-buffered saline served as a negative control. Then, residual biofilm cells on the substrate and the detached cells in the supernatant were collected. Viability was verified by the colony-forming unit (CFU) counting method. Propidium monoazide (PMA) treatment in conjunction with quantitative polymerase chain reaction (qPCR) was also performed to detect the presence of E. faecalis 16S ribonucleic RNA genes. Data were analyzed using 1-way analysis of variance and Tukey or Kruskal-Wallis and Dunn tests. The Pearson R test evaluated the correlation between results from CFU and PMA (α = 5%).
  
  
  RESULTS
  qPCR showed that EDTA detached 99% of biofilm cells, and MSS detached 94% of biofilm cells (both P < .001). In contrast to EDTA, MSS was highly antimicrobial. The treatment promoted an ample log 7 reduction of the attached cells (P < .001), and almost no live cells were detected in the supernatant (P < .001). Positive correlations between CFU and qPCR with PMA were observed (r = 0.959 and r = 0.729).
  
  
  CONCLUSIONS
  EDTA detached cells in biofilms with a minor antimicrobial effect. Besides a great antimicrobial effect, MSS also detached biofilm cells. These dispersals of biofilms give insights into new endodontic biofilm removal strategies.
authors.affiliation: Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherlands; Department of Endodontics, School of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil. Electronic address: dealmeidajosiane@hotmail.com.
authors.forename: Josiane
authors.initials: J
authors.lastname: de Almeida
authors.affiliation: Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: Michel
authors.initials: M
authors.lastname: Hoogenkamp
authors.affiliation: Department of Endodontics, School of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil.
authors.forename: Wilson T
authors.initials: WT
authors.lastname: Felippe
authors.affiliation: Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: Wim
authors.initials: W
authors.lastname: Crielaard
authors.affiliation: Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherlands; Department of Endodontics, Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: Suzette V
authors.initials: SV
authors.lastname: van der Waal
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D003786:Dental Pulp Cavity / Q000382:microbiology; D004492:Edetic Acid / Q000494:pharmacology*; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000502:physiology; D050296:Microbial Viability / Q000187:drug effects; D060888:Real-Time Polymerase Chain Reaction; D012388:Root Canal Irrigants / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*; D013011:Sorbic Acid / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; D012388:Root Canal Irrigants; D012965:Sodium Chloride; D004492:Edetic Acid; D013011:Sorbic Acid
keywords: Biofilm detachment; EDTA; Enterococcus faecalis; biofilm disruption; disinfection; modified salt solution; propidium monoazide; quantitative polymerase chain reaction