Facts About Bleaching Teeth

Tooth bleaching is a popular cosmetic procedure used in modern dentistry that can be done in-office or with take-home bleaching kits. Bleaching kits also can be purchased at the drug store without a trip to the dentist's office. Which method of bleaching is most effective, and how is it done?

Tooth Bleaching and Whitening

The U.S. Food and Drug Administration (FDA) permits the term "bleaching" to be used only when teeth are rendered lighter than their natural color. The use of hydrogen peroxide and carbamide peroxide achieve this effect. "Whitening" methods return the teeth to their prior color. Toothpastes often promote themselves as "whitening" agents. While they may clean the teeth and remove surface debris, they do not have any bleaching properties.

What Causes Tooth Stains?

Teeth become darker over time due the presence of one of two types of stains, extrinsic and intrinsic. Extrinsic staining occurs after prolonged consumption of dark-colored liquids such as red wine and coffee, tobacco use, and everyday wear. Intrinsic stains form on the inside of the teeth and are the result of aging, trauma, exposure to drugs such as tetracycline while the teeth were still growing and excessive fluoride ingestion. Additional factors include an individual's natural tooth color--the color of the teeth that they were born with--and the translucency and thickness of their teeth. Both extrinsic and intrinsic stains can be removed by bleaching.

In-Office Dental Bleaching

The quickest method of teeth bleaching is achieved through an in-office visit, where a gel containing high levels of peroxide is applied to the teeth. First, the teeth are thoroughly cleaned and examined to ensure optimal results. The gums are protected with a dental dam and the gel applied to the teeth (sometimes a dentist will use laser treatment in conjunction with gel treatment). This procedure typically takes about 15 to 20 minutes. Teeth become noticeably whiter after this procedure, although in the case of stubborn staining, a second bleaching procedure may be required. The effects of in-office bleaching last anywhere from six months to a year, after which the procedure may need to be repeated.

Take-home Bleaching Kits

A less expensive option of teeth bleaching is the take-home kit that is prescribed by a dental professional. The kit contains a custom-made tray that fits over all of the teeth, as well as peroxide gel that is lower in concentration than that used in the in-office procedure. The gel is applied to the tray and worn for anywhere from an hour to overnight.

Over-the-Counter Bleaching Kits

Over-the-counter teeth bleaching kits such as Crest Tooth Whitening Strip and Colgate Simply White are the least expensive and most convenient method of whitening the teeth. In some kits, a gel, which consists of carbamide peroxide, is applied to the teeth using a "one-size-fits-all" tray. Alternately, strips or paint-on tools may be used to apply the peroxide to the teeth. The carbamide peroxide in these over-the-counter products is significantly weaker than the hydrogen peroxide used in in-office dental treatments. Therefore, this method is considered to be the least effective.

Does Bleaching Always Work?

Teeth that have "grayed" because of certain drug use are extremely difficult to bleach. Additionally, bleaching only affects natural tooth surfaces. Bonds, veneers, crowns and bridges will not bleach or whiten.

Resources

• Your Dentistry Guide