How do teeth become stained and how can I whiten them?

Most stains on teeth (extrinsic stains) or in the mineral structure of the tooth (intrinsic stains) are organic by nature. These staining substances, often called chromophores, deposit on top of and inside teeth through smoking and the consumption of foods and beverages.
The US Food and Drug Administration (FDA) makes a distinction between:

• Tooth Whitening: treatment that restores the natural shade of the tooth, removing the stains on the surface of the teeth by using cleaning and polishing agents.
• Dental Bleaching: treatment that can bleach teeth beyond their natural shade, removing pigments and stains in the dental structure by means of oxygen radicals.

Unfortunately, the terms “bleaching” and “whitening” are often used as synonyms.