title: In vitro peroxide penetration into the pulp chamber from newer bleaching products.
abstract: OBJECTIVE
  To investigate peroxide penetration from newer bleaching products into the pulp chamber.
  
  
  METHODS
  Fifty extracted human maxillary central incisor teeth were separated into five groups (n = 10). All the teeth were sectioned 3 mm apical to the cemento-enamel junction; the intracoronal pulp tissue was removed, and the pulp chamber filled with acetate buffer. Buccal crown surfaces of teeth in the experimental groups were subjected to either a whitening strip (containing 5.3% hydrogen peroxide-G1) or one of three paint-on liquid whiteners (containing 19% sodium percarbonate peroxide-G2, 18% carbamide peroxide-G3 and 8.7% hydrogen peroxide-G4). The teeth in the control group (G5) were exposed only to distilled water. The acetate buffer solution in each tooth was then transferred to a glass test tube after 30 min and leuco-crystal violet and enzyme horseradish peroxidase were added, producing a blue solution. The optical density of the resultant blue colour in the tubes was measured by a UV-visible spectrophotometer at a wavelength of 596 nm. The values were converted into microgram equivalents of HP using a spectrophotometric calibration curve. Data were analysed statistically using the Kruskal-Wallis Analysis of Variance and the Mann-Whitney U-test.
  
  
  RESULTS
  Statistically significant differences were found between all of the groups (P < 0.05). Pulpal peroxide was not observed in the control group. The amount of hydrogen peroxide (microg) found in the pulp chamber of G1 (0.726 +/- 0.024) > G4 (0.443 +/- 0.017) > G3 (0.231 +/- 0.011) > G2 (0.175 +/- 0.012).
  
  
  CONCLUSIONS
  The peroxides from the whitening strip and paint-on whiteners penetrated into the pulp chamber to varying degrees.
authors: Department of Conservative Dentistry, Faculty of Dentistry, University of Ankara, Ankara, Turkey. ogokay@dentistry.ankara.edu.tr
authors: O
authors: O
authors: Gökay
authors: A
authors: A
authors: Müjdeci
authors: E
authors: E
authors: Algin
mesh_terms: D000077463:Carbamide Peroxide; D002254:Carbonates / Q000493:pharmacokinetics; D003786:Dental Pulp Cavity / Q000378:metabolism*; D004338:Drug Combinations; D005456:Fluorescent Dyes; D005840:Gentian Violet; D006735:Horseradish Peroxidase; D006801:Humans; D006861:Hydrogen Peroxide / Q000493:pharmacokinetics; D016877:Oxidants / Q000493:pharmacokinetics*; D010545:Peroxides / Q000493:pharmacokinetics; D013056:Spectrophotometry, Ultraviolet; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000031:analogs & derivatives / Q000493:pharmacokinetics
chemical_list: D002254:Carbonates; D004338:Drug Combinations; D005456:Fluorescent Dyes; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; C475159:leucocrystal violet; D014508:Urea; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D005840:Gentian Violet; C034738:sodium percarbonate