title: Antibacterial and Toxic Effect of Hydrogen Peroxide Combined with Different Concentrations of Chlorhexidine in Comparison with Sodium Hypochlorite.
abstract: BACKGROUND
  Hydrogen peroxide (H2O2) has been suggested to be used in sequence or in combination with chlorhexidine (CHX) to enhance the antibacterial activity against Enterococcus faecalis, but there is no research in the literature on the safety and effectiveness of this irrigation protocol.
  
  
  OBJECTIVE
  This study aimed to assess the cytocompatibility and antibacterial activity of different concentrations of CHX combined with H2O2in comparison with the activity of 5.25 and 2.5% sodium hypochlorite (NaOCl).
  
  
  METHODS
  Different concentrations of H2O2 (10, 5, 3 and 1%) were exposed to the PDL cells. Then, the solution with minimal cytotoxicity was selected (3% H2O2). The cytocompatibility and antibacterial activity of 0.1, 0.2, 1 and 2% CHX combined with 3% H2O2 were evaluated and compared with 5.25 and 2.5% NaOCl. The differences in the mean viability of PDL cells were evaluated by one-way ANOVA. Kruskal-Wallis and post-hoc Dunn's tests were adopted to compare the antibacterial activity of the solutions against E.faecalis.
  
  
  RESULTS
  The viability of PDL cells was lower when treated with 5.25 or 2.5% NaOCl than all combinations of CHX and H2O2.There was no significant difference in the antibacterial activity of the solutions against E.faecalis, except for the 0.1% CHX + 3% H2O2 combination, which had significantly lower efficacy than other groups.
  
  
  CONCLUSIONS
  All combinations of CHX and H2O2 (used in this study)except 0.1% CHX + 3% H2O2 were efficient irrigants against planktonic E.faecalis and had a better cytocompatibility with PDL cells than 5.25 and 2.5% NaOCl.
authors.affiliation: Dept. of Endodontics, School of Dentistry, Shiraz University of Medical Sciences; Shiraz, Iran.
authors.forename: Hosein
authors.initials: H
authors.lastname: Mirhadi
authors.affiliation: Dept. of Endodontics, School of Dentistry, Shiraz University of Medical Sciences; Shiraz, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Abbaszadegan
authors.affiliation: Dept. of Oral and Maxillofacial Pathology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Ranjbar
authors.affiliation: Dept. of Endodontics, School of Dentistry, Shiraz University of Medical Sciences; Shiraz, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Azar
authors.affiliation: Dept. of Pathology and Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Bita
authors.initials: B
authors.lastname: Geramizadeh
authors.affiliation: Dept. of Oral and Maxillofacial Pathology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Shima
authors.initials: S
authors.lastname: Torabi
authors.affiliation: Dept. of Oral Medicine, School of Dentistry, Shiraz University of Medical Sciences; Shiraz, Iran.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Sadat Aleyasin
authors.affiliation: Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Gholami
keywords: Chlorhexidine; Cytotoxicity; Hydrogen peroxide; Periodontal ligament cells; Sodium hypochlorite