title: Pigmentation susceptibility of teeth after bleaching with 2 systems: an in vitro study.
abstract: OBJECTIVE
  To determine the susceptibility of teeth to darken after bleaching with 35% hydrogen peroxide and 16%carbamideperoxide.
  
  
  METHODS
  Thirty-eight premolars were covered with varnish and the mesiobuccal facets polished up to 0.04 microm, leaving a flat surface. Thirty-six of these premolars were then randomly assigned to 3 groups and the shade of the polished surfaces recorded using a Vita shade guide set in a value disposition. According to the manufacturers'instructions, 12 samples were bleached with 35% hydrogen peroxide (in-office group) and 12 samples with 16%carbamide peroxide (at-home group). The 12 samples in the control group were not bleached. Two days later, the shades of the bleached teeth were recorded; all samples were immersed in silver nitrate 50% for 4 hours,rinsed, and fixed (using a dithioxamidesolution) for 24 hours. Polished surfaces were cleaned and the samples' shade recorded and analyzed using ANOVA. The remaining 2 premolars were bleached the same as those in the test group and analyzed using atomic force microscopy.
  
  
  RESULTS
  The mean shade values were 6.2, 3.7, and 10.9 for in-office samples; 8.8, 1.7, and 6.1 for at-home samples; and 7.8 and 9.4 for the control group. After pigmentation, the at-home group had a lighter shade than the in-office group (P=or<.001). Atomic force microscopy showed no significant surface differences.
  
  
  CONCLUSIONS
  While all the samples were susceptible to pigmentation, this tendency was greater following application of 35% hydrogen peroxide
authors.forename: Victor
authors.initials: V
authors.lastname: Setien
authors.forename: Susan
authors.initials: S
authors.lastname: Roshan
authors.forename: Cynthia
authors.initials: C
authors.lastname: Cala
authors.forename: Robert
authors.initials: R
authors.lastname: Ramirez
mesh_terms: D000293:Adolescent; D001641:Bicuspid; D000077463:Carbamide Peroxide; D003743:Dental Enamel / Q000187:drug effects*; D004338:Drug Combinations; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D018625:Microscopy, Atomic Force; D016877:Oxidants / Q000494:pharmacology*; D010545:Peroxides / Q000494:pharmacology; D012008:Recurrence; D016622:Silver Staining; D013499:Surface Properties; D014073:Tooth Bleaching; D014075:Tooth Discoloration; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology; D055815:Young Adult
chemical_list: D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide