History about teeth whitening
Egyptians used to crush together mint, rock salt, pepper, and iris flowers to use for whitening teeth. Greeks and Romans crushed things such as bones and oyster shells and mixed them with cleansing powders. Some added charcoal or bark for flavor. The Chinese and Indians were making toothpaste with similar materials, but they added mints, salts, and Ginseng for better taste (sounds better than bark or charcoal, right?).
Modern teeth whitening provides better results and less damage to tooth enamel than some techniques of past history. The best whitening systems available have a buffer in the gel that protects the tooth enamel from damage.