title: Effect of carbamide peroxide bleaching agents on the physical properties and chemical composition of enamel.
abstract: OBJECTIVE
  To evaluate the effect of two commercially available carbamide peroxides bleaching agents, Opalescence and Nite-White, in concentrations of 10, 15 and 16%, on enamel.
  
  
  METHODS
  Vickers hardness measurements (VH) were made at the surface and 110 microns below the surface on human enamel samples that were treated for 5 or 10 days, 6 hrs/day. Furthermore, infrared spectrophotometry (IR), Fourier transform infrared spectrophotometer (FTIR) and X-ray diffraction (XRD) measurements were performed after the VH measurements were completed.
  
  
  RESULTS
  Using a one-way ANOVA, statistically significant differences in VH could be established between surface and subsurface VH values. For all groups, including the control group, the surface VH values were statistically significantly higher than subsurface VH. IR, FTIR and XRD established a change from hydroxyapatite to primary calcium ortho phosphate [Ca(H2PO4)2] for all experimental groups except for 10% Opalescense tested for 5 or 10 days.
authors.affiliation: University of Marmara, School of Dentistry, Istanbul, Turkey. halecimilli@superonline.com
authors.forename: H
authors.initials: H
authors.lastname: Cimilli
authors.forename: C H
authors.initials: CH
authors.lastname: Pameijer
mesh_terms: D000704:Analysis of Variance; D002130:Calcium Phosphates / Q000737:chemistry; D000077463:Carbamide Peroxide; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects*; D003747:Dental Enamel Solubility / Q000187:drug effects; D004338:Drug Combinations; D017886:Durapatite / Q000737:chemistry; D006244:Hardness / Q000187:drug effects; D006801:Humans; D010545:Peroxides / Q000009:adverse effects*; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D014073:Tooth Bleaching / Q000009:adverse effects*; D014508:Urea / Q000009:adverse effects* / Q000031:analogs & derivatives; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D004338:Drug Combinations; D010545:Peroxides; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D000077463:Carbamide Peroxide; C485838:calcium phosphate, monobasic, anhydrous; D014508:Urea; D017886:Durapatite; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous