Tooth whiteners use either carbamide peroxide or hydrogen peroxide to bleach the tooth surface. Carbamide peroxide breaks down into hydrogen peroxide and urea when in the mouth, and the hydrogen peroxide whitens the teeth.
When dentists perform a tooth whitening procedure, they use either carbamide peroxide or hydrogen peroxide, which they tailor to the specific patient. They clean the teeth, fill any cavities and make sure that the patient's gums are healthy. Dentists then use 15 to 35 percent peroxide gels. Some dentists couple that with a high-intensity light to make the process a bit faster. After that, the dentist cleans the teeth with pumice and applies hydrogen peroxide gel on the teeth for several minutes.
For an at-home procedure, dentists make molds of patients' mouths and give them a tray to fill with whitening gel and wear for about two hours per day. Over-the-counter whitening trays and strips use a type of hydrogen peroxide gel similar to the professional kind.
In both procedures, reactions due to sensitivity can occur. With the over-the-counter treatment, if sensitivity reactions occur, the patient should reduce use of the whitening product to every other day. Before trying any tooth-whitening procedure, patients should contact a dentist to make sure they are healthy enough for the procedure.