title: Effects of the hydroxyl radical and hydrogen peroxide on tooth bleaching.
abstract: The mechanisms of bleaching of discolored coronal teeth using hydrogen peroxide (H2O2) were investigated. In a scanning-electron-microscopy study, the intertubular dentin and peritubular dentin were dissolved by high concentrations of H2O2, which is used for bleaching. The X-ray diffraction study showed that hydroxyapatite was not influenced by H2O2. In an electron-spin-resonance study, more hydroxyl radical (* OH) was detected as the H2O2 concentration was increased. When amino acids that are core components of dentin proteins, such as proline and alanine, were added to H2O2, the generation of * OH decreased, but there was no change when glycine was added. A nuclear-magnetic-resonance study showed that proline was degraded completely by H2O2, the structure of alanine changed slightly, and glycine was not affected by H2O2. It is suggested that H2O2 and * OH do not influence the inorganic tissue of dentin but attack the organic component of dentin. These facts suggest that * OH has the main role in tooth bleaching with H2O2.
authors.affiliation: Department of Endodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Kawamoto
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Tsujimoto
mesh_terms: D000409:Alanine / Q000494:pharmacology; D003804:Dentin / Q000187:drug effects / Q000648:ultrastructure; D017886:Durapatite / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005998:Glycine / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D017665:Hydroxyl Radical / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D016877:Oxidants / Q000494:pharmacology*; D011392:Proline / Q000494:pharmacology; D014073:Tooth Bleaching; D014075:Tooth Discoloration / Q000188:drug therapy / Q000473:pathology; D014961:X-Ray Diffraction
chemical_list: D016877:Oxidants; D017665:Hydroxyl Radical; D017886:Durapatite; D011392:Proline; D006861:Hydrogen Peroxide; D000409:Alanine; D005998:Glycine