The history of internal bleaching can be traced back more than a century. Chloride was first used inside the pulp chamber as an internal bleaching agent, but the results were not efficacious. In 1958, Pearson was impressed by the positive bleaching effect of 30% hydrogen peroxide on the external surface of teeth. 1 The solution was used internally on a pulpless tooth for 3 days with great success. In 1961, Spasser mixed sodium perborate and water as an internal bleaching medium and placed the mixture into the tooth, employing interval appointments. 2 Nutting and Poe furthered the work of Spasser by replacing water with 30% hydrogen peroxide to maximize.
