This peroxide offers about 25% of the strength of more standard hydrogen peroxide and is slower to take effect. Interestingly, once on the teeth, carbamide peroxide breaks down into hydrogen peroxide. Disadvantages of Teeth WhiteningTeeth whitening is generally very safe, but there are some risks associated with teeth whitening, especially if you intend to do the whitening yourself at home. However, there are still possible problems that can occur when whitening your teeth in a dentist's office (although this is rare). The main potential problems associated with teeth whitening are sensitivity and possible irritation of the gums. In the dentist's office, major problems can occur due to highly concentrated bleach, which can cause pain in the front teeth. Some people are also at greater risk of developing sensitivity in this area. If you have experienced previous gum recession, leaking restorations, or cracks in your teeth, you are at greater risk of developing sensitivity from teeth whitening. If you experience sensitivity from teeth whitening, you will be relieved to know that it usually doesn't last more than a day or two. In this situation, dentists also often recommend a toothpaste containing potassium nitrate. The best teeth whitener