Bleaching is a safe procedure that does not tend to cause serious problems. According to the American Academy of General Dentistry (AAGD), it is successful in 90 percent of patients. There is typically at least a two-shade improvement, measured by a dentist’s tooth shade guide. The rate of success depends on many factors, including the types of stains present, patient compliance with treatment and the type of product used. Discolorations caused by excessive fluoride and the antibiotic tetracycline may not be as responsive to bleaching. Artificial materials, such as crowns and veneers, are not affected by bleaching. The roots of the teeth, which may be exposed due to receding gums, are also not affected by bleaching.

Side effects of bleaching include tooth sensitivity and gum (gingiva) irritation. They tend to go away when the treatment is completed. However, a prescription gel may be recommended to help reduce tooth sensitivity. When over-the-counter bleaching agents are used without the supervision of a dentist, there is the risk of overuse. Overuse can cause irreversible damage to the teeth and/or gums.

Bleaching is not for all patients. People who are allergic to peroxide should not have their teeth bleached, because the bleaching agent contains peroxide. Women who are pregnant or breastfeeding should postpone treatment until delivery and after any breastfeeding is complete. It is not known how the bleaching agents may affect a fetus or breastfeeding infant. It is also recommended that children under the age of 16 avoid bleaching. Children are likely to experience much more tooth sensitivity because the pulp of the tooth has not fully matured. Bleaching may not be appropriate for people with sensitive teeth, gum disease or worn tooth enamel.