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International Journal of Dentistry
Volume 2017 (2017), Article ID 5063521, 6 pages
Research Article

Is It Necessary to Prepare the Enamel before Dental Bleaching?

1Department of Dentistry I, Federal University of Maranhão (UFMA), São Luís, MA, Brazil
2Special Laboratory of Lasers in Dentistry (LELO), Department of Operative Dentistry, School of Dentistry, University of São Paulo (USP), São Paulo, SP, Brazil
3Department of Operative Dentistry, School of Dentistry, University of São Paulo (USP), São Paulo, SP, Brazil

Correspondence should be addressed to Andréa Dias Neves Lago

Received 26 September 2016; Revised 13 December 2016; Accepted 15 January 2017; Published 9 February 2017

Academic Editor: Carlos A. Munoz-Viveros

Copyright © 2017 Andréa Dias Neves Lago et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this in vitro study was to assess the influence of distinct surface treatments on the microhardness and color of enamel that will be bleached. Surface treatments are tested, accordingly: G1, no treatment; G2, 2% sodium fluoride; G3, casein phosphopeptide paste; G4, 2% fluoride+Nd:YAG laser. Forty blocks from bovine teeth composed the sample that were tested in Knoop microhardness () and in color change (). After 24 h, bleaching with 35% hydrogen peroxide was performed for 45 min. Microhardness and color changes (using parameters , , , and ) were assessed before and after bleaching. The data were analyzed by two-way ANOVA and Tukey’s test (). Despite all surface treatments, a reduction of enamel microhardness occurred immediately after bleaching in all groups, being greater in G1. Enamel color changed in all groups. Immediately after bleaching, there was a decrease on enamel microhardness. However, after 7 days, some of those specimens previously treated before bleaching significantly recovered their initial microhardness without influencing the esthetic results of bleaching.