title: Influence of the dentinal wall on the pH of sodium hypochlorite during root canal irrigation.
abstract: BACKGROUND
  The purpose of this study was to evaluate the influence of dentin on the pH levels of different concentrations of sodium hypochlorite (NaOCl) solutions over time and to evaluate if preconditioning of dentin with 17% EDTA or agitation of the NaOCl solution influences these pH levels.
  
  
  METHODS
  A novel clinically representative model that scales with the ratio of the irrigant volume to the dentin surface area of a human root canal was used. Three standardized bovine dentin bars (2 × 2 × 10 mm) were placed in a plastic test tube. A total of 150 tubes were distributed in 29 groups. In the first experiment, the pH of various NaOCl solutions, with different concentrations (3%, 6%, and 9%) and starting pH levels (5 and 12), was monitored during exposure to dentin between 10 and 300 seconds. In a second experiment, the effect of agitation (45 Hz) and pretreatment of dentin with 17% EDTA on the pH levels of various NaOCl solutions was studied after 30 seconds of exposure to dentin. The short-term chemical stability of the tested solutions was assessed for both the concentration and the pH.
  
  
  RESULTS
  The exposure time (P < .001) and concentration of the NaOCl solution (P < .011) significantly influence the pH level after exposure to dentin. However, the change in pH is too small to induce a change in the irrigant antimicrobial/tissue dissolution capacity.
  
  
  CONCLUSIONS
  Agitation of the irrigant and preconditioning of the dentin did not alter the pH (P > .05). Both the pH 5 and pH 12 solutions were chemically stable for 1 hour.
authors.affiliation: Department of Cariology, Endodontology and Pedodontology, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University, Amsterdam, The Netherlands. Electronic address: r.macedo@acta.nl.
authors.forename: Ricardo Gomes
authors.initials: RG
authors.lastname: Macedo
authors.affiliation: Department of Cariology, Endodontology and Pedodontology, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University, Amsterdam, The Netherlands.
authors.forename: Noemi Pascual
authors.initials: NP
authors.lastname: Herrero
authors.affiliation: Department of Cariology, Endodontology and Pedodontology, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University, Amsterdam, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Wesselink
authors.affiliation: Physics of Fluids Group, University of Twente, Enschede, The Netherlands; MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands; MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.
authors.forename: Michel
authors.initials: M
authors.lastname: Versluis
authors.affiliation: Center for Dentistry and Oral Hygiene, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Luc
authors.initials: L
authors.lastname: van der Sluis
mesh_terms: D000818:Animals; D002021:Buffers; D002417:Cattle; D003804:Dentin / Q000187:drug effects / Q000502:physiology*; D004492:Edetic Acid / Q000008:administration & dosage / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D023421:Models, Animal; D012388:Root Canal Irrigants / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D018915:Root Canal Preparation / Q000379:methods*; D012973:Sodium Hypochlorite / Q000008:administration & dosage / Q000737:chemistry*; D007507:Therapeutic Irrigation / Q000379:methods*; D013997:Time Factors
chemical_list: D002021:Buffers; D012388:Root Canal Irrigants; D004492:Edetic Acid; D012973:Sodium Hypochlorite
keywords: Agitation; EDTA; buffer; dentin; hypochlorite; hypochlorous acid; pH; stability