title: Depletion Rate of Hydrogen Peroxide from Sodium Perborate Bleaching Agent.
abstract: BACKGROUND
  Internal bleaching of discolored teeth uses sodium perborate reacting with water to form the active agent, hydrogen peroxide (H2O2). Sodium perborate is replaced at varying time intervals depending on clinician preference and until esthetically acceptable results are achieved, but this is done without scientific basis. This study measured the depletion rate of hydrogen peroxide from sodium perborate as a bleaching agent.
  
  
  METHODS
  Two sodium perborate bleaching products (Odontobleach [Australian Dental Manufacturing, Kenmore Hills, Queensland, Australia] and Endosure Perborate Micro [Dentalife, Ringwood, Victoria, Australia]) and distilled deionized water mixtures at ratios of 25 μg/mL, 50 μg/mL, and 100 μg/mL were placed into sealed microtubes and incubated at 37°C. H2O2concentrations were measured at 23 time points over 4 weeks. Quantification of H2O2concentrations was obtained using a ferrothiocyanate oxidation reduction reaction followed by spectrophotometry readings.
  
  
  RESULTS
  The H2O2concentration rapidly peaked within 27 hours and reached a plateau by about 3 days (75 hours). Low levels of H2O2were evident beyond 3 days and for at least 28 days. No significant differences were found between the 2 sodium perborate products. There was also no significant difference in the depletion rate between the different ratios.
  
  
  CONCLUSIONS
  Based on the chemistry of H2O2depletion, the minimum replacement interval for the bleaching agent is 3 days. Frequent replacements of the perborate clinically may be unnecessary because of the continued presence of low H2O2levels for at least 28 days. Although these data cannot be extrapolated to the clinical situation, they set a baseline for further studies to address the many clinical variables influencing internal bleaching.
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Liliann
authors.initials: L
authors.lastname: Tran
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Orth
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia. Electronic address: parashos@unimelb.edu.au.
authors.forename: Peter
authors.initials: P
authors.lastname: Parashos
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Ying
authors.initials: Y
authors.lastname: Tao
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Calvin W J
authors.initials: CW
authors.lastname: Tee
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Vineet Thenalil
authors.initials: VT
authors.lastname: Thomas
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Georgina
authors.initials: G
authors.lastname: Towers
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Diem Thuy
authors.initials: DT
authors.lastname: Truong
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Vinen
authors.affiliation: Melbourne Dental School, Oral Health Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Reynolds
mesh_terms: D057886:Bleaching Agents / Q000737:chemistry*; D001881:Borates / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000032:analysis / Q000737:chemistry*; D013053:Spectrophotometry; D014073:Tooth Bleaching
chemical_list: D057886:Bleaching Agents; D001881:Borates; D006861:Hydrogen Peroxide; C027707:sodium perborate
keywords: Hydrogen peroxide depletion; internal bleaching; intracoronal bleaching; sodium perborate; walking bleach