Reaction kinetics of sodium ascorbate and dental bleaching gel

Freire, Andrea; Souza, Evelise M.; de Menezes Caldas, Danilo Biazzetto; Rosa, Edvaldo Antônio Ribeiro; Bordin, Cynthia França Wolanski; de Carvalho, Ricardo Marins; Vieira, Sergio

doi:10.1016/j.jdent.2009.07.008

« Previous Next »Journal of Dentistry
Volume 37, Issue 12 , Pages 932-936, December 2009

Reaction kinetics of sodium ascorbate and dental bleaching gel

Andrea Freire
- School of Dentistry, Pontifical Catholic University of Parana, Curitiba, Parana, Brazil
- Corresponding author at: Programa de Pos-graduação em Odontologia, R. Imaculada Conceição, 1155, Prado Velho, Curitiba, PR 80215-901, Brazil. Tel.: +55 41 3271 1637; fax: +55 41 3271 1405.
Evelise M. Souza
- School of Dentistry, Pontifical Catholic University of Parana, Curitiba, Parana, Brazil
Danilo Biazzetto de Menezes Caldas
- School of Dentistry, Pontifical Catholic University of Parana, Curitiba, Parana, Brazil
Edvaldo Antônio Ribeiro Rosa
- School of Dentistry, Pontifical Catholic University of Parana, Curitiba, Parana, Brazil
Cynthia França Wolanski Bordin
- School of Pharmacy, Pontifical Catholic University of Parana, Curitiba, Parana, Brazil
Ricardo Marins de Carvalho
- College of Dentistry, University of Florida, Gainesville, Florida, USA
Sergio Vieira
- School of Dentistry, Pontifical Catholic University of Parana, Curitiba, Parana, Brazil

Received 25 March 2009; received in revised form 27 July 2009; accepted 28 July 2009. published online 05 August 2009.

Abstract

Objective

The aim of this study was to establish the reaction kinetics of 35% hydrogen peroxide and sodium ascorbate and to determine the mass of antioxidant required to neutralize the bleaching gel.

Methods

The method used to quantify sodium ascorbate was based on the United States Pharmacopeia (1995)²⁶. Oxidation–reduction titration was used to confirm the concentration of hydrogen peroxide and sodium ascorbate and to determine the reaction kinetics between them.

Results

The results indicated a direct correlation between the mass of hydrogen peroxide and that of the antioxidant agent. In addition, 5min of contact was sufficient to neutralize the hydrogen peroxide used.

Conclusion

This in vitro study showed that the amount of sodium ascorbate required for reduction of hydrogen peroxide is directly related to the concentration of the latter. In addition, the reaction kinetics between oxidant and antioxidant showed that a longer application time for sodium ascorbate does not influence the effectiveness of the reaction and that 5min is sufficiently long for this antioxidant to exert an antioxidant effect.

Keywords: Dental bleaching, Hydrogen peroxide, Sodium ascorbate, Antioxidant