title: Chemical analysis of enamel and dentin following the application of three different at-home bleaching systems.
abstract: OBJECTIVE
  To determine the change in the chemical composition of enamel and dentin as well as to evaluate the differences in surface texture of the same dental hard tissues following three at-home bleaching systems in vitro.
  
  
  METHODS
  Sixty extracted intact human anterior teeth were used in this study. Thirty teeth were used as samples for enamel, and the buccal surfaces of the remaining 30 teeth were abraded and used as dentin samples. Prior to bleaching treatments, calcium (Ca), phosphorus (P), potassium (K), sodium (Na), magnesium (Mg), fluoride (F), and oxygen (O) levels of each sample were measured using an energy dispersive spectrometer. The teeth were then randomly allocated into three groups according to the bleaching system used, as follows: GI, 10% carbamide peroxide (CP); GII, 20% CP; GIII, and 35% CP. Following the bleaching treatments, Ca, P, K, Na, Mg, F, and O measurements were repeated. The surface configurations were examined using scanning electron microscopy (SEM). The data were analyzed using Wilcoxon signed rank and Kruskal-Wallis tests followed by the Dunn test.
  
  
  RESULTS
  All three bleaching systems tested caused similar changes in the chemical composition of enamel and dentin. Bleaching systems decreased Ca and K, while F and O levels increased in enamel. In dentin, Ca, P, and K levels decreased; however, Na, F, and O levels increased. SEM observations revealed no deleterious effect on enamel and dentin.
  
  
  CONCLUSIONS
  The use of home bleaching agents could affect the chemical composition of dental hard tissues, whereas the change in the chemical composition of enamel and dentin was not affected by the CP concentration of the bleaching systems used.
authors.affiliation: Department of restorative Dentistry, Hacette University, School of Dentistry, Sihhiye, Ankara, Turkey. fyalcin@hacettepe.edu.tr
authors.forename: F Y
authors.initials: FY
authors.lastname: Cakir
authors.forename: Y
authors.initials: Y
authors.lastname: Korkmaz
authors.forename: E
authors.initials: E
authors.lastname: Firat
authors.forename: S S
authors.initials: SS
authors.lastname: Oztas
authors.forename: S
authors.initials: S
authors.lastname: Gurgan
mesh_terms: D002118:Calcium / Q000032:analysis; D000077463:Carbamide Peroxide; D003743:Dental Enamel / Q000737:chemistry* / Q000648:ultrastructure; D003804:Dentin / Q000737:chemistry* / Q000648:ultrastructure; D005459:Fluorides / Q000032:analysis; D006801:Humans; D006813:Humidity; D008274:Magnesium / Q000032:analysis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000032:analysis; D010545:Peroxides / Q000008:administration & dosage*; D010758:Phosphorus / Q000032:analysis; D011188:Potassium / Q000032:analysis; D012964:Sodium / Q000032:analysis; D013052:Spectrometry, X-Ray Emission; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000008:administration & dosage*; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives*; D014867:Water / Q000737:chemistry
chemical_list: D010545:Peroxides; D058205:Tooth Bleaching Agents; D014867:Water; D010758:Phosphorus; D000077463:Carbamide Peroxide; D014508:Urea; D012964:Sodium; D008274:Magnesium; D005459:Fluorides; D011188:Potassium; D010100:Oxygen; D002118:Calcium