There are many different methods available for bleaching teeth. All of the teeth may be bleached at once, or some of the teeth may be bleached. In fact, a single tooth may be bleached to closely match the surrounding teeth in a process called selective bleaching.

Bleaching can be either external or internal. During external bleaching, chemicals are placed on the surface of the tooth. Options for external bleaching include:

• In-office bleaching. A dentist applies a 15 percent to 35 percent hydrogen peroxide gel or paste to the teeth. Currently, all of these bleaching agents have the American Dental Association Seal of Acceptance. In-office bleaching can be expensive but it provides the fastest results. It often can be completed in about one hour, although in some cases multiple treatments may be needed. Some dentists may use light, heat or a laser as well. It is believed that light or heat speeds up the bleaching process, but some studies refute these claims. The American Dental Association (ADA) has not recognized the use of lasers or light with the seal of acceptance, because studies demonstrating the effectiveness of the procedure have not yet been completed.
  
  
• At-home dentist-supervised bleaching. Patients use a mouthpiece molded for their teeth to apply the bleaching agent at home. The dentist provides the custom fit mouthpiece, bleaching agent, instructions for use and monitors the process with regular appointments. Currently, all of the bleaching agents used in this process that have the ADA Seal of Acceptance use a 10 percent carbamide peroxide gel. The mouthpiece is lightweight enough to be worn comfortably and is often thin enough to talk or work while wearing it.
  
  
• Over-the-counter products. Many over-the-counter whitening products are also available. However, the ADA recommends that patients consult their dentists about the use of over-the-counter products. Over-the-counter mouthpieces are not custom-fitted and may cause leaking and potential swallowing of the bleaching agent. This can irritate the gums and reduce the bleaching effectiveness. Overuse can damage the teeth, gums and mouth.

Some products are available that do not actually bleach the teeth, but can remove some surface stains. One widely used example is over-the-counter whitening toothpaste. Mild abrasives are present in nearly all toothpastes to help remove some surface stains. “Whitening” toothpastes remove more stains through the use of chemicals or polishing agents. However, toothpaste can only remove some surface stains.