title: Is It Necessary to Prepare the Enamel before Dental Bleaching?
abstract: 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 (n= 10) and in color change (n= 10). After 24 h, bleaching with 35% hydrogen peroxide was performed for 45 min. Microhardness and color changes (using parameters ΔE, ΔL, Δa, and Δb) were assessed before and after bleaching. The data were analyzed by two-way ANOVA and Tukey's test (p< 0.05). 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.
authors.affiliation: Department of Dentistry I, Federal University of Maranhão (UFMA), São Luís, MA, Brazil.
authors.forename: Andréa Dias Neves
authors.identifier: 0000-0003-4303-6399
authors.initials: AD
authors.lastname: Lago
authors.affiliation: Special Laboratory of Lasers in Dentistry (LELO), Department of Operative Dentistry, School of Dentistry, University of São Paulo (USP), São Paulo, SP, Brazil; Department of Operative Dentistry, School of Dentistry, University of São Paulo (USP), São Paulo, SP, Brazil.
authors.forename: Patrícia Moreira
authors.identifier: 0000-0001-9508-6369
authors.initials: PM
authors.lastname: de Freitas
authors.affiliation: Department of Dentistry I, Federal University of Maranhão (UFMA), São Luís, MA, Brazil.
authors.forename: Erika Michele Dos Santos
authors.initials: EM
authors.lastname: Araújo
authors.affiliation: Department of Operative Dentistry, School of Dentistry, University of São Paulo (USP), São Paulo, SP, Brazil.
authors.forename: Adriana Bona
authors.identifier: 0000-0002-4167-2079
authors.initials: AB
authors.lastname: Matos
authors.affiliation: Department of Operative Dentistry, School of Dentistry, University of São Paulo (USP), São Paulo, SP, Brazil.
authors.forename: Narciso
authors.initials: N
authors.lastname: Garone-Netto