title: Stabilizing sodium hypochlorite at high pH: effects on soft tissue and dentin.
abstract: BACKGROUND
  When sodium hypochlorite solutions react with tissue, their pH drops and tissue sorption decreases. We studied whether stabilizing a NaOCl solution at a high pH would increase its soft-tissue dissolution capacity and effects on the dentin matrix compared with a standard NaOCl solution of the same concentration and similar initial pH.
  
  
  METHODS
  NaOCl solutions were prepared by mixing (1:1) a 10% stock solution with water (standard) or 2 mol/L NaOH (stabilized). Physiological saline and 1 mol/L NaOH served as the controls. Chlorine content and alkaline capacity of NaOCl solutions were determined. Standardized porcine palatal soft-tissue specimens and human root dentin bars were exposed to test and control solutions. Weight loss percentage was assessed in the soft-tissue dissolution assay. Three-point bending tests were performed on the root dentin bars to determine the modulus of elasticity and flexural strength. Values between groups were compared using one-way analysis of variance with the Bonferroni correction for multiple testing (α < .05).
  
  
  RESULTS
  Both solutions contained 5% NaOCl. One milliliter of the standard and the stabilized solution consumed 4.0 mL and 13.7 mL of a 0.1-mol/L HCl solution before they reached a pH level of 7.5, respectively. The stabilized NaOCl dissolved significantly more soft tissue than the standard solution, and the pH remained high. It also caused a higher loss in elastic modulus and flexure strength (P < .05) than the control solutions, whereas the standard solution did not.
  
  
  CONCLUSIONS
  NaOH-stabilized NaOCl solutions have a higher alkaline capacity and are thus more proteolytic than standard counterparts.
authors.affiliation: Division of Preventive Dentistry, University of Zürich Center of Dental Medicine, Switzerland.
authors.forename: Holger
authors.initials: H
authors.lastname: Jungbluth
authors.forename: Monika
authors.initials: M
authors.lastname: Marending
authors.forename: Gustavo
authors.initials: G
authors.lastname: De-Deus
authors.forename: Beatrice
authors.initials: B
authors.lastname: Sener
authors.forename: Matthias
authors.initials: M
authors.lastname: Zehnder
mesh_terms: D000818:Animals; D002424:Caustics / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D002713:Chlorine / Q000032:analysis; D003804:Dentin / Q000187:drug effects*; D003808:Dentin Solubility / Q000187:drug effects; D055119:Elastic Modulus; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009061:Mouth Mucosa / Q000187:drug effects; D010159:Palate / Q000187:drug effects*; D018583:Pliability; D012388:Root Canal Irrigants / Q000737:chemistry* / Q000494:pharmacology; D012965:Sodium Chloride / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000737:chemistry* / Q000494:pharmacology; D012995:Solubility; D013314:Stress, Mechanical; D013552:Swine; D014092:Tooth Root / Q000187:drug effects; D014867:Water / Q000737:chemistry
chemical_list: D002424:Caustics; D012388:Root Canal Irrigants; D014867:Water; D012965:Sodium Chloride; D002713:Chlorine; D012972:Sodium Hydroxide; D012973:Sodium Hypochlorite