title: Effects of fluoride or nanohydroxiapatite on roughness and gloss of bleached teeth.
abstract: OBJECTIVE
  The aim of this study was to describe roughness and gloss alterations of enamel after treatment with 38% hydrogen peroxide (HP) and after polishing with 2% neutral sodium fluoride (SF) or a dental tooth paste containing nanohydroxiapatite particles (nHA) using power spectral density (PSD) description, roughness parameters (Ra, RMS, and Z range) and gloss analysis.
  
  
  METHODS
  An atomic force microscope (AFM) and a spectrophotometer were used to analyze eighteen specimens of upper incisors. After initial analyses, all specimens were bleached with 38% HP for 135 min. The specimens were analyzed after bleaching. Nine specimens were polished with SF (Group Fluor) and the other nine specimens were polished with nHA (Group nHA), then all specimens were analyzed after polishing. Roughness and gloss were analyzed with ANOVA and Tukey's t-test.
  
  
  RESULTS
  No statistical difference was found for Ra and RMS among initial, after bleaching and after polishing in both groups. For Z range, Group nHA showed a significant decrease after polishing. Bleaching with 38% HP did not increase the PSD in the spatial frequency of the visible light spectrum range in both groups. After polishing, nHA group showed a decrease in PSD for all morphological wavelengths. Gloss did not show statistical difference after bleaching in both groups. Gloss showed significant increase after polishing with nHA.
  
  
  CONCLUSIONS
  bleaching treatment with 38% HP didn't alter enamel surface roughness or gloss. PSD analyses were very suitable to identifying the morphological changes on the surfaces.
authors.affiliation: Departamento de Dentística, Faculdade de Odontologia da Universidade de São Paulo, SP, Brazil. anacarolfreitas@usp.br
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Pedreira De Freitas
authors.forename: Sérgio Brossi
authors.initials: SB
authors.lastname: Botta
authors.forename: Fernanda De Sá
authors.initials: Fde S
authors.lastname: Teixeira
authors.forename: Maria Cecília Barbosa Silveira
authors.initials: MC
authors.lastname: Salvadori
authors.forename: Narciso
authors.initials: N
authors.lastname: Garone-Netto
mesh_terms: D017886:Durapatite / Q000378:metabolism*; D005459:Fluorides / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D013053:Spectrophotometry; D013499:Surface Properties; D014070:Tooth / Q000187:drug effects* / Q000502:physiology*; D058205:Tooth Bleaching Agents / Q000378:metabolism*
chemical_list: D058205:Tooth Bleaching Agents; D017886:Durapatite; D006861:Hydrogen Peroxide; D005459:Fluorides