To evaluate the impact of saliva on the bleaching potential of hydrogen peroxide.
Method:
Test dye - A lissamine green B dye solution was added to pooled human saliva in a container. A 1% H2O2 dentifrice or a regular fluoride dentifrice was added to separate containers. The ratios of dye/saliva and dentifrice were selected to prepare a 1:1 (w/w) and a 1:2 (w/w) slurry when mixed. Containers were equilibrated at 37ᵒC. To start each test the dye/saliva was mixed with the dentifrice. After a 1 minute mixing time, the bleaching was stopped with the addition of acid. The toothpaste solids were removed by centrifugation, and the absorbance spectrum of each sample was measured. Bound food stains - Saliva coated hydroxyapatite disks were soaked in a coffee, tea, and wine solution for 3 hrs. Baseline L*, a*, and b* values were measured with a spectrophotometer. Each disk was soaked in a 37ºC dentifrice slurry made from pooled human saliva for 2 min and rinsed with water. L*, a*, and b* values were measured after treatment. Analysis of variance was used to compare the mean ΔW* values with p<0.05 indicating significant differences.
Result:
Test dye - The absorbance at 633 nm was present in the samples treated with regular fluoride dentifrice and not in the samples treated with 1% H2O2 dentifrice. This was true for both the 1:1 and 1:2 slurries. Bound Food Stains – The change in whitening index for 1% H2O2dentifrice was -12.3 ± 3.4 while the change for regular fluoride dentifrice was -1.7 ± 2.9. The p-value between products was 0.015.
Conclusion:
In-vitro testing demonstrated that saliva does not impact the ability of a dentifrice containing 1% H2O2 to bleach both colored dyes or common food stains.