title: Antagonistic interactions between sodium hypochlorite, chlorhexidine, EDTA, and citric acid.
abstract: BACKGROUND
  Root canal irrigants play a significant role in the elimination of microorganisms, tissue dissolution, and the removal of debris and smear layer. No single solution is able to fulfill these actions completely; therefore, their association is required. The aim of this investigation was to review the antagonistic interactions occurring when sodium hypochlorite (NaOCl), chlorhexidine (CHX), EDTA, and citric acid (CA) are used together during endodontic treatment.
  
  
  METHODS
  A search was performed in the electronic database Medline (articles published through 2011; English language; and the following search terms or combinations: "interaction AND root canal irrigant or endodontic irrigant or sodium hypochlorite or chlorhexidine," "sodium hypochlorite AND EDTA or ethylenediaminetetraacetic acid or citric acid or chelating agent or chlorhexidine," and "chlorhexidine AND EDTA or ethylenediaminetetraacetic acid or citric acid or chelating agent") to identify publications that studied unwanted chemical interactions between NaOCl, CHX, and EDTA and CA.
  
  
  RESULTS
  The search identified 1,285 publications; 19 fulfilled the inclusion/exclusion criteria of the review. Their research methodology was classified as either in vitro or ex vivo.
  
  
  CONCLUSIONS
  Antagonistic interactions included the loss of free available chlorine for NaOCl when in contact with chelators, which consequently reduced the tissue dissolution capability and to a lesser extent antimicrobial activities. When CHX and NaOCl are mixed, a precipitate forms that can present detrimental consequences for endodontic treatment, including a risk of discoloration and potential leaching of unidentified chemicals into the periradicular tissues. CHX and EDTA mixtures cause a precipitate, whereas CHX and CA do not exhibit interaction.
authors.affiliation: Warwick Dentistry, The University of Warwick, Coventry, United Kingdom. grossifede@yahoo.com
authors.forename: Giampiero
authors.initials: G
authors.lastname: Rossi-Fedele
authors.forename: Esma J
authors.initials: EJ
authors.lastname: Doğramaci
authors.forename: Andrea R
authors.initials: AR
authors.lastname: Guastalli
authors.forename: Liviu
authors.initials: L
authors.lastname: Steier
authors.forename: Jose Antonio Poli
authors.initials: JA
authors.lastname: de Figueiredo
mesh_terms: D000891:Anti-Infective Agents, Local / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry*; D055598:Chemical Phenomena; D011232:Chemical Precipitation; D002710:Chlorhexidine / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry*; D003116:Color; D004336:Drug Antagonism; D004492:Edetic Acid / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D012388:Root Canal Irrigants / Q000737:chemistry*; D012973:Sodium Hypochlorite / Q000737:chemistry*; D012995:Solubility
chemical_list: D000891:Anti-Infective Agents, Local; D002614:Chelating Agents; D012388:Root Canal Irrigants; D019343:Citric Acid; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D002710:Chlorhexidine