title: Spectrophotometric evaluation of peroxide penetration into the pulp chamber from whitening strips and gel: An in vitro study.
abstract: OBJECTIVE
  To investigate pulp chamber penetration of different concentration of hydrogen peroxide.
  
  
  METHODS
  Fifty extracted human maxillary central incisor teeth were taken and grouped into five (n = 10). All teeth were cut approximately 3 mm apical to the cemento-enamel junction. Pulp was removed and the pulp chamber filled with acetate buffer. Buccal crown surfaces of teeth in the experimental groups were subjected to whitening strip and paint on whitener gel. Control group teeth were exposed to distilled water. The acetate buffer solution in each tooth was then transferred to a glass test tube after 30 min. Leuco-crystal violet dye and enzyme horse radish peroxidase were added. The optical density of resultant blue color in the tubes was measured by UV-visible spectrophotometer. The values were converted into microgram equivalents of hydrogen peroxide.
  
  
  RESULTS
  The results were evaluated statistically using nonparametric Mann-Whitney U test. Whitening strip showed the lowest pulpal peroxide penetration whereas paint on whitener gel showed highest pulpal peroxide penetration.
  
  
  CONCLUSIONS
  This study demonstrate that peroxide is readily penetrate into the pulp chamber of teeth.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, King George's Medical University, Lucknow, India.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Bharti
authors.forename: Kk
authors.initials: K
authors.lastname: Wadhwani
keywords: Bleaching gel; peroxide; peroxide penetration; whitening strips