title: Tooth bleaching increases dentinal protease activity.
abstract: Hydrogen peroxide is an oxidative agent commonly used for dental bleaching procedures. The structural and biochemical responses of enamel, dentin, and pulp tissues to the in vivo bleaching of human (n = 20) premolars were investigated in this study. Atomic force microscopy (AFM) was used to observe enamel nanostructure. The chemical composition of enamel and dentin was analyzed by infrared spectroscopy (FTIR). The enzymatic activities of dental cathepsin B and matrix metalloproteinases (MMPs) were monitored with fluorogenic substrates. The amount of collagen in dentin was measured by emission of collagen autofluorescence with confocal fluorescence microscopy. The presence of Reactive Oxygen Species (ROS) in the pulp was evaluated with a fluorogenic 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) probe. Vital bleaching of teeth significantly altered all tested parameters: AFM images revealed a corrosion of surface enamel nanostructure; FTIR analysis showed a loss of carbonate and proteins from enamel and dentin, along with an increase in the proteolytic activity of cathepsin-B and MMPs; and there was a reduction in the autofluorescence of collagen and an increase in both cathepsin-B activity and ROS in pulp tissues. Together, these results indicate that 35% hydrogen peroxide used in clinical bleaching protocols dramatically alters the structural and biochemical properties of dental hard and soft pulp tissue.
authors.affiliation: Centro Interdisciplinar de Investigação Bioquímica, UMC, Mogi das Cruzes, Brazil.
authors.forename: C
authors.initials: C
authors.lastname: Sato
authors.forename: F A
authors.initials: FA
authors.lastname: Rodrigues
authors.forename: D M
authors.initials: DM
authors.lastname: Garcia
authors.forename: C M P
authors.initials: CM
authors.lastname: Vidal
authors.forename: D H
authors.initials: DH
authors.lastname: Pashley
authors.forename: L
authors.initials: L
authors.lastname: Tjäderhane
authors.forename: M R
authors.initials: MR
authors.lastname: Carrilho
authors.forename: F D
authors.initials: FD
authors.lastname: Nascimento
authors.forename: I L S
authors.initials: IL
authors.lastname: Tersariol
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000737:chemistry / Q000187:drug effects; D002254:Carbonates / Q000032:analysis; D002401:Cathepsin B / Q000032:analysis; D002863:Chromogenic Compounds; D003094:Collagen / Q000032:analysis; D057056:Cysteine Proteases / Q000032:analysis / Q000187:drug effects*; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects; D003782:Dental Pulp / Q000737:chemistry / Q000187:drug effects; D003804:Dentin / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology*; D005260:Female; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008297:Male; D020782:Matrix Metalloproteinases / Q000032:analysis / Q000187:drug effects*; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D049329:Nanostructures / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000032:analysis; D017550:Spectroscopy, Fourier Transform Infrared; D058205:Tooth Bleaching Agents / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D002254:Carbonates; D002863:Chromogenic Compounds; D005452:Fluoresceins; D005456:Fluorescent Dyes; D017382:Reactive Oxygen Species; D058205:Tooth Bleaching Agents; C029569:diacetyldichlorofluorescein; D003094:Collagen; D006861:Hydrogen Peroxide; D057056:Cysteine Proteases; C533912:CTSB protein, human; D002401:Cathepsin B; D020782:Matrix Metalloproteinases