title: The use of NaOCl in combination with CHX produces cytotoxic product.
abstract: OBJECTIVE
  The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) yields a "precipitate potentially toxic" (PPT). The aim of this study was to evaluate the tissue response to implanted polyethylene tubes filled with PPT-soaked fibrin sponge.
  
  
  METHODS
  Forty rats received four polyethylene tubes each; each tube was filled with fibrin sponge soaked by 2.5 % NaOCl, 2.0 % CHX, PPT (2.5 % NaOCl plus 2.0 % CHX), or not soaked (control). The observation time points were 7, 15, 30, 60, and 90 days. At each time point, eight animals were killed, and the tubes and surrounding tissues were removed, fixed, and prepared for light microscopic analysis by performing glycol methacrylate embedding, serial cutting into 3-μm sections, and hematoxylin-eosin staining. Qualitative and quantitative evaluations of the reactions were performed. Results were statistically analyzed by Kruskal-Wallis test (p < 0.05).
  
  
  RESULTS
  All chemical solutions caused moderate reactions at 7 days. On day 30, PPT group was more cytotoxic than the control group and the CHX group (p < 0.05). On days 15 and 60, PPT group was more cytotoxic than the control group (p < 0.05). On day 90, there was no statistically significant difference between the different groups.
  
  
  CONCLUSIONS
  PPT is more cytotoxic than NaOCl and CHX alone, particularly in the short term.
  
  
  CONCLUSIONS
  Protocols which suggest the use of CHX and NaOCl must be revised because this mixture produces cytotoxic product.
authors.affiliation: Department of Endodontics, Araçatuba Dental School, UNESP-Universidade Estadual Paulista, R. José Bonifácio, 1193, Araçatuba, São Paulo, Brazil, lucianocintra@foa.unesp.br.
authors.forename: Luciano Tavares Angelo
authors.initials: LT
authors.lastname: Cintra
authors.forename: Simone
authors.initials: S
authors.lastname: Watanabe
authors.forename: Renata Oliveira
authors.initials: RO
authors.lastname: Samuel
authors.forename: Aguinaldo Cândido
authors.initials: AC
authors.lastname: da Silva Facundo
authors.forename: India Olinta
authors.initials: IO
authors.lastname: de Azevedo Queiroz
authors.forename: Eloi
authors.initials: E
authors.lastname: Dezan-Júnior
authors.forename: João Eduardo
authors.initials: JE
authors.lastname: Gomes-Filho
mesh_terms: D000818:Animals; D002710:Chlorhexidine / Q000008:administration & dosage*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012973:Sodium Hypochlorite / Q000008:administration & dosage*
chemical_list: D012973:Sodium Hypochlorite; D002710:Chlorhexidine
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