title: In vitro evaluation of a novel 6% hydrogen peroxide tooth whitening product.
abstract: OBJECTIVE
  The aims of this study were to evaluate the in vitro tooth whitening effects of a novel 6% hydrogen peroxide containing tooth whitener Xtra White (XW) on extrinsic stain and intrinsic tooth colour and the effects on enamel and dentine microhardness. In addition, to determine the levels of peroxide found in tooth pulp chambers after treatment with XW in vitro.
  
  
  METHODS
  Extrinsic stain changes were determined by measuring colour changes of tea stained hydroxyapatite discs after treatment with water, placebo gel, XW or Colgate Simply White (CSW). Intrinsic tooth colour changes were determined by treating extracted human teeth in vitro with a placebo gel, XW or CSW for a simulated two weeks use and measuring colour differences with a chroma meter. Teeth treated with placebo gel and XW were cross-sectioned and the subsurface enamel and dentine was polished and the microhardness determined. The peroxide concentration found in extracted tooth pulp chambers was determined spectrophotometrically.
  
  
  RESULTS
  XW gave significantly more extrinsic stain removal (p<0.0001) and an increase in tooth whiteness (p<0.05) than a placebo gel, but was not significantly different to CSW. There were no significant differences in subsurface enamel and dentine microhardness values for the placebo and XW treated teeth. The mean concentration of peroxide found in the tooth pulp chambers was 0.44 mM, which is over 3000 times below the concentration reported to cause pulpal enzyme damage.
  
  
  CONCLUSIONS
  XW has been shown to be an effective tooth whitening product in vitro with support for its safety on subsurface enamel and dentine together with its safety on tooth pulp tissue.
authors.affiliation: Unilever Oral Care, Quarry Road East, Bebington, Wirral, UK. andrew.joiner@unilever.com
authors.forename: Andrew
authors.initials: A
authors.lastname: Joiner
authors.forename: Gopal
authors.initials: G
authors.lastname: Thakker
mesh_terms: D003116:Color; D045424:Complex Mixtures; D003743:Dental Enamel / Q000187:drug effects; D003786:Dental Pulp Cavity / Q000187:drug effects; D003802:Dentifrices / Q000627:therapeutic use; D003804:Dentin / Q000187:drug effects; D017886:Durapatite; D006244:Hardness; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000627:therapeutic use*; D016877:Oxidants / Q000008:administration & dosage / Q000627:therapeutic use*; D010545:Peroxides; D010919:Placebos; D012449:Safety; D013053:Spectrophotometry; D013662:Tea; D013997:Time Factors; D014070:Tooth / Q000187:drug effects / Q000473:pathology; D014073:Tooth Bleaching; D014075:Tooth Discoloration / Q000628:therapy*
chemical_list: C475021:Colgate Simply White Clear Whitening Gel; D045424:Complex Mixtures; D003802:Dentifrices; D016877:Oxidants; D010545:Peroxides; D010919:Placebos; D013662:Tea; D017886:Durapatite; D006861:Hydrogen Peroxide