In vitro action of various bleaching agents on the microhardness of human dentin.

The authors verified a decrease in human dentin microhardness after application of the following bleaching agents for 72 hours: sodium perborate+water, sodium perborate + 3% hydrogen peroxide, sodium perborate + 30% hydrogen peroxide, Endoperox (crystallized hydrogen peroxide), Proxigel (carbimide peroxide), and 30% hydrogen peroxide. Sodium perborate+water and sodium perborate + 3% hydrogen peroxide caused less of a decrease in dentin microhardness than Endoperox, Proxigel and 30% hydrogen peroxide which caused the greatest decreases in dentin microhardness. Sodium perborate + 30% hydrogen peroxide fell into a statistically intermediate position.