title: Effects of reducing agents on birefringence dentin collagen after use of different endodontic auxiliary chemical substances.
abstract: BACKGROUND
  The aim of this study was to evaluate the effect of 10% ascorbic acid or 10% sodium ascorbate on organic matrix collagen of bovine dentin root canal walls after irrigation with 5.25% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA), or 0.9% sodium chloride.
  
  
  METHODS
  Eighty bovine incisors were randomly divided into 8 groups (n = 10): group 1, 0.9% sodium chloride (control); group 2, 5.25% NaOCl + 17% EDTA (NaOCl + EDTA); group 3, 5.25% NaOCl + 17% EDTA + 10% ascorbic acid (NaOCl + EDTA + AA); group 4, 5.25% NaOCl + 17% EDTA + 10% sodium ascorbate (NaOCl + EDTA + SA); group 5, 5.25% NaOCl (NaOCl); group 6, 17% EDTA; group 7, 10% ascorbic acid (AA); and group 8, 10% sodium ascorbate (SA). Teeth were chemomechanically prepared, submitted to histologic processing, and stained with Sirius Red dye to be analyzed under polarized light microscopy. Absorbance assay was also performed to confirm the loss of collagen.
  
  
  RESULTS
  NaOCl + EDTA and NaOCl groups presented a significantly different birefringence pattern compared with the control group (P < .05). The measurement of the optical retardations of NaOCl + EDTA + SA indicated that this group was not statistically different from the control group. Although the measurement of the optical retardations of NaOCl + EDTA + AA was statistically different from the control group, the results were significantly higher than for NaOCl + EDTA. The birefringence of EDTA, AA, and SA groups was not statistically different from that of control group. The absorbance assay of NaOCl + EDTA and NaOCl groups confirmed the loss of collagen (P < .05).
  
  
  CONCLUSIONS
  It is possible to conclude that 5.25% NaOCl, whether associated or not with 17% EDTA, causes birefringence alterations and loss of dentin collagen. These alterations reduced the ability of Sirius Red to bind with collagen fiber molecules. The reductions in the optical retardation values could be reversed by the application of either 10% ascorbic acid or 10% sodium ascorbate after 5.25% sodium hypochlorite and 17% EDTA irrigation.
authors.affiliation: Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Danna Mota
authors.initials: DM
authors.lastname: Moreira
authors.forename: Judith Pessoa
authors.initials: JP
authors.lastname: de Andrade Feitosa
authors.forename: Sérgio Roberto Peres
authors.initials: SR
authors.lastname: Line
authors.forename: Alexandre Augusto
authors.initials: AA
authors.lastname: Zaia
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D001718:Birefringence; D002417:Cattle; D003094:Collagen / Q000032:analysis / Q000737:chemistry / Q000187:drug effects*; D003786:Dental Pulp Cavity / Q000187:drug effects; D003804:Dentin / Q000737:chemistry / Q000187:drug effects*; D004492:Edetic Acid / Q000494:pharmacology; D005109:Extracellular Matrix / Q000187:drug effects; D008859:Microscopy, Polarization; D011897:Random Allocation; D019163:Reducing Agents / Q000494:pharmacology*; D012388:Root Canal Irrigants / Q000494:pharmacology*; D012973:Sodium Hypochlorite / Q000494:pharmacology
chemical_list: D019163:Reducing Agents; D012388:Root Canal Irrigants; D003094:Collagen; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D001205:Ascorbic Acid