title: Separate whitening effects on enamel and dentin after fourteen days.
abstract: The purpose of this study was to investigate the mechanism of action of a bleaching agent, as it relates to enamel and dentin. Twenty-six extracted human molar teeth were sectioned at the cemento-enamel junction and were randomly assigned to two groups. L*a*b* readings were taken with a spectrophotometer: on buccal surfaces of the crown, at enamel and dentin. The teeth were exposed to carbamide peroxide or placebo gel and L*a*b* scores were again recorded to determine color changes. Treatments were compared using ancova test with baseline color as the covariate. Relative to placebo, buccal surfaces exhibited the greatest Deltab* and DeltaL* color change. On buccal surfaces, the adjusted mean (SE) treatment differences were -7.8 (1.00) for Deltab* and 5.7 (0.97) for DeltaL, with groups differing significantly (p < 0.0001). On enamel surfaces, treatment differences were -3.6 (0.61) for Deltab* and 4.6 (0.80) for DeltaL* (p < 0.0001). Dentin exhibited the least color improvement. Adjusted mean (SE) treatment differences were -1.9 (0.87) for Deltab* and 2.4 (1.10) for DeltaL*, with groups differing significantly (p < 0.02) on dentin color change. The majority of color change seen on the buccal surface of tooth crowns exposed to carbamide peroxide 15% was because of the color change in enamel. As compared to enamel, dentin was less affected after 14 days.
authors.affiliation: Tufts University, School Dental Medicine, Boston, Massachusetts, USA.
authors.forename: Gerard
authors.initials: G
authors.lastname: Kugel
authors.forename: Jason
authors.initials: J
authors.lastname: Petkevis
authors.forename: Sevil
authors.initials: S
authors.lastname: Gurgan
authors.forename: Eileen
authors.initials: E
authors.lastname: Doherty
mesh_terms: D000704:Analysis of Variance; D000077463:Carbamide Peroxide; D003116:Color; D003743:Dental Enamel / Q000187:drug effects*; D003804:Dentin / Q000187:drug effects*; D004338:Drug Combinations; D006801:Humans; D016877:Oxidants / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry*; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea