The over-the-counter tooth whitening industry is booming thanks to millions of Americans who want increasingly whiter and brighter smiles

But UAB prosthodontist Mike McCracken, D.M.D., said a quick trip to the dentist before you whiten is a bright decision.

"People should have their teeth cleaned and examined by a dentist before using any teeth bleaching product. In some cases, darkening teeth can signal more than a cosmetic problem. People can have a variety of diseases they may not be aware of. Big cavities, periodontal disease, some oral cancers and some medications can cause staining or darkening of the teeth."

Whitening is most effective for teeth that have become discolored due to yellowing from age, tobacco, red wine, coffee or tea.