title: The effect of 16 percent carbamide peroxide on enamel staining susceptibility.
abstract: BACKGROUND
  Recently, vital bleaching by carbamide peroxide has become more popular; therefore, it is necessary to study the effect of this agent on enamel and dentin.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the effect of a 16 percent carbamide peroxide bleaching gel, Vivastyle, on enamel staining susceptibility.
  
  
  METHODS
  Thirty bovine specimens were selected and randomly divided into two groups of 15. The experimental group was subjected to Vivastyle gel and then was immersed in coffee for half an hour daily for three weeks. The control group was only immersed in coffee. The teeth were evaluated using a colorimeter to measure L*, a*, b* of each tooth. Value (black to white) is denoted as L*, wheres chroma (a* b*) is denoted as red (+a*), green (_a*), yellow (+b*), and blue (_b*). Total color differences between two colors (deltaE) were calculated using the following formula: deltaE = [(deltaL*)2 + (deltaa*)2+(deltab*)2]: deltaE1.Bleached, AE2: bleached and immersed in coffee, deltaE3: immersed in coffee.
  
  
  RESULTS
  Mean differences were: deltaE1 = 9.478, deltaE2 = 13.808 and deltaE3 = 7.230. Paired comparison by use of Duncan test showed there was a significant difference between deltaE1 and deltaE2 (P0.000); and t test showed there was no significant difference between deltaE3 and deltaE1. (P0.08 > 0.05), but deltaE3 showed a significant difference with deltaE2(P0.000).
  
  
  CONCLUSIONS
  After vital bleaching, the enamel staining susceptibility significantly increased.
authors.affiliation: Department of Operative Dentistry, Dental School and Dental Research Center of Mashhad University of Medical Sciences, Mashhad, Iran. dr_marjaneh@yahoo.com
authors.forename: Marjaneh
authors.initials: M
authors.lastname: Ghavamnasiri
authors.forename: Maryam
authors.initials: M
authors.lastname: Bidar
authors.forename: Arezou Habibi
authors.initials: AH
authors.lastname: Rad
authors.forename: M Sadegh
authors.initials: MS
authors.lastname: Namazikhah
mesh_terms: D000818:Animals; D000077463:Carbamide Peroxide; D002417:Cattle; D003069:Coffee / Q000009:adverse effects; D003743:Dental Enamel / Q000187:drug effects*; D004338:Drug Combinations; D006861:Hydrogen Peroxide / Q000009:adverse effects*; D010545:Peroxides / Q000009:adverse effects*; D014073:Tooth Bleaching / Q000009:adverse effects*; D014075:Tooth Discoloration / Q000139:chemically induced*; D014508:Urea / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D003069:Coffee; D004338:Drug Combinations; D010545:Peroxides; C500417:Vivastyle; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide