Bleaching and non-bleaching products are the two basic kinds of whitening products available today. Non-bleaching products normally use abrasives or chemicals and only remove surface stains on teeth. Bleaching products work with a chemical called peroxide and can brighten your teeth several shades. Peroxide is available in different strengths; therefore results may vary from product to product. The higher strength peroxide is usually dispensed by dental offices, where as over the counter bleaching systems have lesser strength.
Another process employs the use of a special gel that is placed inside a flexible device you wear around your teeth for a certain period of time. After you remove the device, you must use a second bleaching agent, followed by a special light to activate the chemical action. Mildly stained teeth usually only require one session of bleaching.