Journal of Dentistry
Volume 37, Issue 3 , Pages 185-190, March 2009

Effect of home bleaching systems on enamel nanohardness and elastic modulus☆

  • Shereen S. Azer

      Affiliations

    • Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, OH, USA
    • Corresponding Author InformationCorresponding author at: Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, 305 West 12th Avenue, #191, P.O. Box 182357, Columbus, OH 43218-2357, USA. Tel.: +1 614 292 7467; fax: +1 614 292 9422.
    • ,
  • Camilo Machado

      Affiliations

    • Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, OH, USA
    • ,
  • Eliana Sanchez

      Affiliations

    • Division of Primary Care, The Ohio State University College of Dentistry, Columbus, OH, USA
    • ,
  • Robert Rashid

      Affiliations

    • Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, OH, USA

Received 25 September 2008; received in revised form 10 November 2008; accepted 11 November 2008.

Abstract 

Objectives

The purpose of this study was to evaluate the nanohardness and elastic modulus of human enamel after treatment with tray and strip bleaching systems.

Methods

Fifty-five human enamel samples were exposed to five different bleaching agents. Nanoindentations were made before and after bleaching treatments following the manufacturer's directions using a Nanoindenter XP (MTS Systems Corporation, Oak Ridge, TN, USA). Nanohardness and elastic modulus measurements were obtained and the results were statistically analyzed using a repeated measures analysis of variance with a post-hoc Tukey–Kramer multiple comparison test.

Results

Nanohardness and elastic modulus measurements showed decrease of mean values for each group except the control which remained the same. There were significant differences due to time (before and after treatment) and material effects in nanohardness (P<0.0001) and elastic modulus (P=0.0241). Measurements after treatment showed significant decrease in nanohardness between all groups and the control group. There was a significant difference in hardness between CP and TO after treatment. Additionally, there were significant differences in elastic modulus between the control group when compared to OB and TO after treatment. While there were significant changes in the elastic modulus due to treatment for both CP and TO, there were no significant differences between any of the groups after treatment.

Conclusions

Nanohardness and elastic modulus of human enamel were significantly decreased after the application of home-bleaching systems.

Keywords: Tooth bleaching, Tooth whitening, Enamel nanohardness, Enamel elastic modulus, Bleaching trays, Whitening strips

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☆ Presented at the 37th Annual Meeting of the AADR, April 2–5, 2008, Dallas, Texas.

PII: S0300-5712(08)00303-5

doi:10.1016/j.jdent.2008.11.005

Journal of Dentistry
Volume 37, Issue 3 , Pages 185-190, March 2009

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