Effect of bleaching on mercury release from amalgam fillings and antioxidant enzyme activities: a pilot study

J Esthet Restor Dent. Jan-Feb 2015;27(1):29-36. doi: 10.1111/jerd.12092. Epub 2014 Feb 15.


Objective: The aim of this pilot clinical study was to determine the mercury release from amalgam fillings and antioxidant enzyme activities (Superoxide Dismutase [SOD] and Catalase[CAT] ) in body fluids after exposure to two different vital tooth bleaching systems.

Material and methods: Twenty eight subjects with an average age of 25.6 years (18-41) having at least two but not more than four Class II amalgam fillings on each quadrant arch in the mouth participated in the study. Baseline concentrations of mercury levels in whole blood, urine, and saliva were measured by a Vapor Generation Accessory connected to an Atomic Absorption Spectrometer. Erythrocyte enzymes, SOD, and CAT activities in blood were determined kinetically. Subjects were randomly assigned to two groups of 14 volunteers. Group 1 was treated with an at-home bleaching system (Opalescence PF 35% Carbamide Peroxide, Ultradent), and Group 2 was treated with a chemically activated office bleaching system (Opalescence Xtra Boost 38% Hydrogen Peroxide, Ultradent) according to the manufacturer's recommendations. Twenty-four hours after bleaching treatments, concentrations of mercury and enzymes were remeasured.

Results: There were no significant differences on mercury levels in blood, urine, and saliva before and after bleaching treatments (p > 0.05). No differences were also found in the level of antioxidant enzyme activities (SOD and CAT) before and after treatments (p > 0.05). Mercury release did not affect the enzyme activities (p > 0.05).

Conclusion: Bleaching treatments either office or home did not affect the amount of mercury released from amalgam fillings in blood, urine, and saliva and the antioxidant-enzyme activities in blood.

Clinical significance: Bleaching treatments with the systems tested in this pilot study have no deleterious effect on the mercury release from amalgam fillings and antioxidant enzymes in body fluids.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Catalase / metabolism*
  • Dental Amalgam / chemistry*
  • Erythrocytes / enzymology
  • Female
  • Humans
  • Male
  • Mercury / metabolism*
  • Pilot Projects
  • Spectrophotometry, Atomic
  • Superoxide Dismutase / metabolism*
  • Tooth Bleaching / methods*


  • Dental Amalgam
  • Catalase
  • Superoxide Dismutase
  • Mercury