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Hydrogen Peroxide Versus Sodium Hypochlorite: All a Matter of pH?


Trautmann, Erik; Attin, Thomas; Mohn, Dirk; Zehnder, Matthias (2021). Hydrogen Peroxide Versus Sodium Hypochlorite: All a Matter of pH? Journal of Endodontics, 47(2):297-302.

Abstract

Introduction: Hydrogen peroxide (H2O2) and sodium hypochlorite (NaOCl) solutions are similar in that they contain oxidizing agents with a bleaching effect. NaOCl solutions are stable at a high pH, at which they also exert increased cleansing/proteolysis. On the other hand, H2O2 solutions are natively acidic, yet gain bleaching power on organic stains when alkalized. It was investigated whether alkalizing a H2O2 solution would also let it dissolve soft tissue or increase its bleaching power on blood-stained dentin.

Methods: The stability of alkalized H2O2 solutions was assessed by iodometric titration. Soft tissue dissolution was investigated on porcine palatal mucosa. The bleaching effect (ΔL∗) after 60 minutes of exposure was monitored in blood-stained human dentin using a calibrated spectrophotometer. To compare similar molarities, 2.5% H2O2 solutions were used here, and 5.0% NaOCl was used as the positive control, whereas nonbuffered saline solution served as the negative control.

Results: Adding alkali (NaOH) to the H2O2 solutions rendered them unstable in a dose-dependent manner. A H2O2 solution of pH 11.1 was chosen for the main experiments (tissue dissolution and bleaching effect) and compared with a native counterpart (pH = 4.7). Alkalizing the H2O2 solution had no discernible effect on its soft tissue dissolution or bleaching power (P = .75 compared with the native H2O2 solution). The NaOCl solution of similar molar concentration had a considerably (P < .001) higher tissue dissolving and bleaching effect under current conditions.

Conclusions: The proteolytic/bleaching effects of NaOCl solutions are unique and cannot be achieved by altering the pH of peroxide solutions.

Keywords: Bleaching; dentin; hydrogen peroxide; tissue dissolution.

Abstract

Introduction: Hydrogen peroxide (H2O2) and sodium hypochlorite (NaOCl) solutions are similar in that they contain oxidizing agents with a bleaching effect. NaOCl solutions are stable at a high pH, at which they also exert increased cleansing/proteolysis. On the other hand, H2O2 solutions are natively acidic, yet gain bleaching power on organic stains when alkalized. It was investigated whether alkalizing a H2O2 solution would also let it dissolve soft tissue or increase its bleaching power on blood-stained dentin.

Methods: The stability of alkalized H2O2 solutions was assessed by iodometric titration. Soft tissue dissolution was investigated on porcine palatal mucosa. The bleaching effect (ΔL∗) after 60 minutes of exposure was monitored in blood-stained human dentin using a calibrated spectrophotometer. To compare similar molarities, 2.5% H2O2 solutions were used here, and 5.0% NaOCl was used as the positive control, whereas nonbuffered saline solution served as the negative control.

Results: Adding alkali (NaOH) to the H2O2 solutions rendered them unstable in a dose-dependent manner. A H2O2 solution of pH 11.1 was chosen for the main experiments (tissue dissolution and bleaching effect) and compared with a native counterpart (pH = 4.7). Alkalizing the H2O2 solution had no discernible effect on its soft tissue dissolution or bleaching power (P = .75 compared with the native H2O2 solution). The NaOCl solution of similar molar concentration had a considerably (P < .001) higher tissue dissolving and bleaching effect under current conditions.

Conclusions: The proteolytic/bleaching effects of NaOCl solutions are unique and cannot be achieved by altering the pH of peroxide solutions.

Keywords: Bleaching; dentin; hydrogen peroxide; tissue dissolution.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Dental Medicine > Clinic of Conservative and Preventive Dentistry
Dewey Decimal Classification:610 Medicine & health
Scopus Subject Areas:Health Sciences > General Dentistry
Uncontrolled Keywords:General Dentistry
Language:English
Date:1 February 2021
Deposited On:30 Nov 2021 12:54
Last Modified:26 Apr 2024 01:36
Publisher:Elsevier
ISSN:0099-2399
OA Status:Hybrid
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1016/j.joen.2020.10.016
PubMed ID:33129899
  • Content: Published Version
  • Language: English
  • Licence: Creative Commons: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)