Do-it-yourself bleaching kits can cause problems.

• Position: Teeth - Dental care - Brief Article

People who want to brighten their smiles are opting for over-the-counter bleaching kits instead of visiting their dentist's office. While generally safe, these products have the potential to cause an infection or nerve damage, warns David McFadden, associate professor of oral and maxillofacial surgery, The University of Texas Southwestern Medical Center at Dallas. He suggests consulting a dentist so preexisting conditions can be diagnosed and treated before starting any type of bleaching regimen. "If a person has deep cavities, the bleach could have an unimpeded route to the blood vessels, nerves, and bone that are found at the root of the tooth. It can potentially cause a bad toothache or precipitate an infection."

People with active periodontal disease may also notice soft-tissue shrinkage. "This is not gum recession, but many patients perceive this as a negative side effect. In actuality, bleaching provides short-term improvement," he explains. "The effervescent action of the bleach helps keep the teeth cleaner."

The color of one's teeth is determined by genetics. Dentin, a hard yellow substance that surrounds the pulp, shows through the enamel, so most teeth appear slightly yellowish. Other factors that affect tooth color are aging, tetracycline medications, overfluoridated water, and chromogenic agents found in coffee, tea, and carbonated drinks.

"Many over-the-counter bleaching agents are weak and will not create a drastic change in tooth color," McFadden indicates. "And since the bleaching trays are not custom-fitted to your teeth, the uneven...