Teeth whitening is all about peroxide

Baby boomers have become a huge target market for tooth-whitening products because teeth yellow naturally with age. This effect can be exacerbated by smoking, as well as by drinking coffee, tea and red wine. The most effective teeth-whitening agents use peroxide (hydrogen or carbamide) to bleach the deep layers of teeth where toothpaste can't reach. The whitening process usually requires daily application for up to two weeks, but light therapy and peroxide can be used in the dentist's office to speed things up and shorten the bleaching process to as little as one hour. Experts say bleaching works best for yellow stains; gray teeth, which can result from certain antibiotics, are much harder to whiten.

Many of the reviews represented in our list of sources test one sample of each type of whitening kit or service and then determine which method produces the greatest effect with the least inconvenience. We also look to research abstracts presented at the annual General Session of the International Association for Dental Research (IADR), where dental scientists test specific whitening products (primarily Crest strips) against one another. (Some of these studies are sponsored by tooth-whitener manufacturers.) We find it interesting that the results almost always favor the manufacturer funding the study. That said, the findings do show that the effectiveness of any tooth whitening product depends largely upon the percentage of peroxide it contains combined with the length of time the product is in contact with teeth. This is the same conclusion drawn by other experts and reviewers.


Do whitening toothpastes work?

Store shelves are filled with so-called teeth-whitening toothpastes (*Est. $3 to $7), which usually cost more than regular toothpaste. However, most reviewers say that whitening toothpastes are less than impressive and that you can achieve the same result by brushing for the recommended two minutes with regular toothpaste. This is because peroxide and time are needed to have a whitening effect on teeth. Many whitening toothpastes only contain abrasives or chemical polishing agents that clean the surface of teeth, just like ordinary toothpaste; those that do contain peroxide aren't in contact with your teeth long enough to have much of an effect. Most reviewers suggest you're better off brushing well with ordinary toothpaste and putting those extra dollars toward a true bleaching product.

Our report on toothpaste covers products that best clean surface stains, which reviews say is about all you can expect from toothpaste. We find that whether a toothpaste says "whitening" on the tube makes no difference in its performance.


Teeth-whitening side effects and safety

Many users of whitening products experience temporary tooth and gum pain, which in some cases can be severe. Reviews on Amazon.com, TeethWhiteningReviews.com and Drugstore.com often mention pain and sensitivity. A 2006 study published in the Cochrane Database of Systematic Reviews examines data from 25 separate trials on whitening products. The most common side effects are mild or moderate tooth sensitivity and gum irritation. Tooth sensitivity corresponds to the concentration of peroxide; higher percentages of peroxide are apt to cause more irritation.

Tooth sensitivity may help guard against the overuse of whitening products. Consumers may be more apt to remove a product at the instructed time if their teeth or gums begin to ache. Overuse of whitening products can be detrimental. In an article on WebMD.com, Van Haywood, DMD, a professor in the department of oral rehabilitation in the School of Dentistry at the Medical College of Georgia, says that with extreme whitener use, teeth may become transparent.

When used properly, however, almost all data on tooth whitening attests to its safety. A 2006 review published in the Journal of Esthetic and Restorative Dentistry finds no correlation between hydrogen peroxide tooth-whitening products and oral cancer. Many studies at a 2007 session International Association for Dental Research (IADR) examine whether whitening can damage the structure of the tooth, including the enamel. One study shows that the three products tested (NiteWhite ACP, Opalescence PF and Tres White) decrease enamel hardness and density. Most studies show no harmful effects, although long-term data are not presented. Data from a report presented at a 2005 Materials Research Society meeting suggest that whitening can reduce the hardness of tooth enamel. In testing on extracted teeth, a carbamide peroxide solution of 10 percent reduces enamel hardness by 22 percent. A 35 percent carbamide solution reduces enamel hardness by 82 percent. Researchers note, however, that results may differ in a live environment where saliva is present. There is little evidence that occasional whitening treatments cause damage, but a few studies do note that some people find teeth-whitening psychologically addictive.

Some people simply shouldn't undergo tooth whitening, according to a WebMD.com article.. Bleaching is not recommended in children younger than 16 because the pulp chamber, or nerve of the tooth, is enlarged until this age. Whitening procedures could irritate the pulp or cause it to become sensitive. Pregnant or lactating women should also forgo tooth whitening. For the most part, people who have gum disease or teeth with worn enamel are similarly discouraged. Additionally, cavities should be treated before you undergo any whitening regimens.

Experts say to remember the following when choosing a tooth whitener:

  • The American Dental Association recommends discussing the options with your dentist who can determine if you are a good candidate for teeth whitening. It's best to choose a dentist-supervised whitening plan.
  • Bleaching effectiveness is directly related to the percent of peroxide and length of time it's in contact with your teeth. Over-the-counter tooth-whitening products generally contain no more than 10 percent peroxide. Professional teeth-whitening processes can use up to 43 percent peroxide.
  • Bleaching works best for yellow teeth. If you have gray or brown teeth, a whitener won't be as effective.
  • Crowns, fillings and dental veneers are not affected by lightening products. This is something to keep in mind if you have a prominent crown or bridge.
  • Have your teeth professionally cleaned before beginning a whitening treatment. To achieve the best results, you'll want to make sure you've removed surface stains before you begin the teeth-whitening process.
  • Use desensitizing toothpaste before and after whitening. This can help to reduce sensitizing effects. For more information, see our separate report on toothpaste.

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