Compounds For A Whiter Smile
Bleaching agents for whitening teeth date to at least the early 1900's. Today, the most common bleaching agent in toothpaste is a compound called carbamide peroxide, which in the mouth forms hydrogen peroxide. The hydrogen peroxide in turn breaks down into water and oxygen. The free oxygen is a powerful bleaching agent because it combines with materials in the stains and lightens their color. A few brands of toothpaste contain a different type of bleaching agent, citric acid, which is found in lemons and other citrus fruits and acts as a mild bleach.
Toothpastes do not contain enough bleaching agents to lighten heavy stains beyond the normal effect of abrasives, however. Products called home tooth bleaching kits claim to offer stronger whitening power. But according to the American Dental Association (ADA), these products may be dangerous due to their high peroxide content. In 1989, the ADA warned that the regular use of home bleaching kits may temporarily damage the soft tissues of the mouth, delay healing of already damaged tissue, or damage tooth pulp by traveling down tubules in the enamel to the pulp. None of these kits had received approval from the ADA as of mid-1993.