free radical method is an antioxidant assay based on electron-transferthat produces a violet solution in ethanol (10). This free radical, stable at room temperature, is reduced in the presence of an antioxidant molecule, giving rise to colorless ethanol solution. The use of the DPPH assay provides an easy and rapid way to evaluate antioxidants by spectrophotometry (10), so it can be useful to assess various products at a time. Due to the lack of evidence about which solution can be more effective as an antioxidant or even if there are other solutions with equal or more capacity to eliminate free radicals from dental surfaces after bleaching procedures, the purpose of this study was to evaluate the antioxidant activity of several agents proposed for reversion of problems caused by bleaching procedures using the DPPH free radical assay.