title: Endodontic chelators induce nitric oxide expression by murine-cultured macrophages.
abstract: BACKGROUND
  Endodontic chelators may extrude to apical tissues during instrumentation activating cellular events on periapical tissues. This study assessed in vitro the expression of nitric oxide (NO) concentrations by murine peritoneal macrophages after contact with MTAD (Dentsply/Tulsa, Tulsa, OK), Tetraclean (Ogna Laboratori Farmaceutici, Muggio, Italy), Smear Clear (Sybron Endo, Orange, CA), and EDTA (Biodinâmica, Ibiporã, PR, Brazil).
  
  
  METHODS
  Macrophage cells were obtained from Swiss mice after peritoneal lavage. Chelators were diluted in distilled water obtaining 12 concentrations, and MTT assay identified the concentrations, per group, displaying the highest cell viability (analysis of variance, p < 0.01). Selected concentrations were tested for NO expression using Griess reaction. Culture medium and lipopolysaccharide (LPS) were used as controls.
  
  
  RESULTS
  Analysis of variance and Tukey tests showed that all chelators displayed elevated NO concentrations compared with the negative control (p < 0.01). MTAD induced the lowest NO expression, followed by Tetraclean, EDTA, and Smear Clear. No difference was observed between MTAD and Tetraclean (p > 0.01), Tetraclean and EDTA (p > 0.01), and EDTA and Smear Clear (p > 0.01). LPS ranked similar to both EDTA and Smear Clear (p > 0.01).
  
  
  CONCLUSIONS
  The tested endodontic chelators displayed severe proinflammatory effects on murine-cultured macrophages. Citric acid-based solutions induce lower NO release than EDTA-based irrigants.
authors.affiliation: Department of Semiology and Clinics, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil. ferpappen@yahoo.com.br
authors.forename: Fernanda Geraldes
authors.initials: FG
authors.lastname: Pappen
authors.forename: Erick Miranda
authors.initials: EM
authors.lastname: Souza
authors.forename: Luciano
authors.initials: L
authors.lastname: Giardino
authors.forename: Iracilda Zepponi
authors.initials: IZ
authors.lastname: Carlos
authors.forename: Mario Roberto
authors.initials: MR
authors.lastname: Leonardo
authors.forename: Renato
authors.initials: R
authors.lastname: de Toledo Leonardo
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002614:Chelating Agents / Q000633:toxicity*; D019343:Citric Acid / Q000633:toxicity; D004492:Edetic Acid / Q000633:toxicity; D018836:Inflammation Mediators / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis*; D012388:Root Canal Irrigants / Q000633:toxicity*
chemical_list: D002614:Chelating Agents; D018836:Inflammation Mediators; D012388:Root Canal Irrigants; D019343:Citric Acid; D009569:Nitric Oxide; D004492:Edetic Acid