title: Tissue dissolution and modifications in dentin composition by different sodium hypochlorite concentrations.
abstract: OBJECTIVE
  To determine the organic matter dissolution and changes in dentin chemical composition promoted by different concentrations of NaOCl over time.
  
  
  METHODS
  Fragments of bovine muscle tissue were weighed before and after 5, 10, and 15 min of immersion in the groups (n=10): G1- 0.9% saline solution; G2- 1% NaOCl; G3- 2.5% NaOCl; and G4- 5% NaOCl. Bovine dentin fragments were subjected to the same irrigants and absorption spectra were collected by Attenuated Total Reflectance of Fourier Transform Infrared Spectroscopy (ATR-FTIR) before and after 0,5, 1, 2, 3, 5, 8, and 10 min of immersion in the solutions. The ratios of the amide III/phosphate and carbonate/phosphate absorption bands were determined. The tissue dissolution and carbonate/phosphate ratios were submitted to the two-way analysis of variance (ANOVA) with Tukey's multiple-comparison test (α<0.05) and to the one-way analysis of variance with Tukey's (α<0.05). The amide III/phosphate ratio was analyzed by Friedman test (α<0.05) and the Kruskal-Wallis test with Dunn's post-hoc (α<0.05).
  
  
  RESULTS
  The increase in NaOCl concentration and contact time intensified the dissolution of organic matter and dentin collagen with reduction in the amide III/phosphate ratio. Significant differences between all groups (p<0.05) were observed in the dissolution of organic matter at 10 min and in the amide III/phosphate ratio between the saline solution and 5% NaOCl at 5 min. The carbonate/phosphate ratio decreased significantly in G2, G3, and G4 after 0,5 min of immersion (p<0.05), but more alterations did not occur in the subsequent periods (p>0.05). Intergroup differences were not observed in this ratio (p>0.05).
  
  
  CONCLUSIONS
  The increase in the exposure time and in the concentration of NaOCl solution lead to an increase in the tissue dissolution and dentin collagen deproteination. Furthermore, some carbonate ions are removed from the dentin inorganic phase by the NaOCl.
authors.affiliation: - Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Dentística, Endodontia e Materiais Odontológicos, Bauru, SP, Brasil.
authors.forename: Talita
authors.initials: T
authors.lastname: Tartari
authors.affiliation: - Universidade de São Paulo, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Departamento de Física, Ribeirão Preto, SP, Brasil.
authors.forename: Luciano
authors.initials: L
authors.lastname: Bachmann
authors.affiliation: - Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Dentística, Endodontia e Materiais Odontológicos, Bauru, SP, Brasil.
authors.forename: Amanda Garcia Alves
authors.initials: AG
authors.lastname: Maliza
authors.affiliation: - Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Dentística, Endodontia e Materiais Odontológicos, Bauru, SP, Brasil.
authors.forename: Flaviana Bombarda
authors.initials: FB
authors.lastname: Andrade
authors.affiliation: - Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Dentística, Endodontia e Materiais Odontológicos, Bauru, SP, Brasil.
authors.forename: Marco Antonio Hungaro
authors.initials: MA
authors.lastname: Duarte
authors.affiliation: - Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Dentística, Endodontia e Materiais Odontológicos, Bauru, SP, Brasil.
authors.forename: Clovis Monteiro
authors.initials: CM
authors.lastname: Bramante
mesh_terms: D000818:Animals; D002417:Cattle; D003094:Collagen / Q000187:drug effects; D003804:Dentin / Q000737:chemistry* / Q000187:drug effects*; D004202:Disinfectants / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007101:Immersion; D009132:Muscles / Q000187:drug effects; D012016:Reference Values; D012388:Root Canal Irrigants / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000737:chemistry*; D012995:Solubility / Q000187:drug effects; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties / Q000187:drug effects; D013997:Time Factors
chemical_list: D004202:Disinfectants; D012388:Root Canal Irrigants; D003094:Collagen; D012973:Sodium Hypochlorite