title: An atomic force microscopy study on the effect of bleaching agents on enamel surface.
abstract: OBJECTIVE
  The aim of the present study was to evaluate the effect of three peroxide-containing bleaching agents, Opalescence, Nite White and a 30% hydrogen peroxide solution, on enamel surfaces using Atomic Force Microscopy (AFM).
  
  
  METHODS
  Fifteen non-carious human incisors (ten maxillary and five mandibular, extracted for periodontal reasons) were used. The teeth were divided randomly into three groups of five, according to the bleaching agents. The labial surface of each tooth was imaged by AFM before and after treatment. Each bleaching agent was applied for a total of 28 h (in individual 4 h treatments). The specimens were examined only after 28 h of treatment.
  
  
  RESULTS
  On comparing the AFM images of untreated and treated enamel, surface alterations were observed after 28 h of treatment with Opalescence, Nite White and 30% hydrogen peroxide solution. Several grooves present in the enamel surface of untreated teeth became deeper after the bleaching procedure. The depths of the grooves increased in each case. The increase in the depth of grooves was more pronounced in the case of the 30% H2O2 solution.
  
  
  CONCLUSIONS
  Home-use bleaching agents are capable of causing enamel surface alterations. It is hypothesized that the peroxide-containing bleaching agents affect the organic phase of enamel. Peroxides can affect not only the surface but also the inner structure of enamel. As a result of its low molecular weight, hydrogen peroxide can penetrate into the enamel. Thus, inner oxidative effects are more likely to occur in the subsurface enamel where more organic material is present and oxidation is capable of altering the outer enamel and the surface.
authors.affiliation: School of Dentistry, University Medical School of Debrecen, Hungary. hegedus@fogaszat.dote.hu
authors.forename: C
authors.initials: C
authors.lastname: Hegedüs
authors.forename: T
authors.initials: T
authors.lastname: Bistey
authors.forename: E
authors.initials: E
authors.lastname: Flóra-Nagy
authors.forename: G
authors.initials: G
authors.lastname: Keszthelyi
authors.forename: A
authors.initials: A
authors.lastname: Jenei
mesh_terms: D000180:Acrylic Resins; D000077463:Carbamide Peroxide; D003743:Dental Enamel / Q000187:drug effects* / Q000648:ultrastructure; D004337:Drug Carriers; D004338:Drug Combinations; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use*; D007180:Incisor; D018625:Microscopy, Atomic Force; D008970:Molecular Weight; D016877:Oxidants / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use*; D010084:Oxidation-Reduction; D010545:Peroxides / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use*; D011145:Polyvinyls; D013997:Time Factors; D014073:Tooth Bleaching; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000627:therapeutic use
chemical_list: D000180:Acrylic Resins; D004337:Drug Carriers; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D011145:Polyvinyls; C006912:carboxypolymethylene; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide