How well do over-the-counter teeth whitening products really work?

ATLANTA - Americans spend hundreds of millions of dollars each year trying to get whiter, brighter teeth.

In Atlanta, Inman Park Dentistry's Dr. Alex Rodriguez says teeth whiteners are one of the top things his patients are asking about.

"Whitening is hugely popular, always has been," Rodriguez says.  "Everybody wants white teeth."

Your dentist can do an in-office teeth bleaching procedure, send you home with a whitening kit, or you can try drugstore whiteners.

"Some of the over-the-counter stuff works well, some doesn't," Rodriguez says.  "The toothpastes don't really work that well. The mouthwashes don't really work that well."

But Rodriguez says drugstore whitening strips are pretty effective.

"Those work great," he says.  "They're real basic. They're like a little piece of tape that you put in and fold over the teeth.  It's got little drops of hydrogen peroxide gel on there, and it soaks into the teeth. Those usually stay on 20, 30 minutes or so a day."

The peroxide in the strips -- or over-the-counter trays -- will gradually lift surface stains from things like coffee or red wine.

But, only natural teeth, not tooth-colored restorations, can be whitened, and you may have some gum or tooth sensitivity, usually temporary.

Now, if you had a significant cavity, and you're trying to bleach that tooth, you're going to feel it," Rodriguez warns.  "It's going to get real sensitive. And, so I certainly caution people that they should get their teeth checked out. They should make sure everything's healthy before they try whitening."

It can take a couple of weeks of daily use to start seeing results, and you can do touch-ups.

If you want to keep stains from coming back, he says, grab a glass of water after drinking or eating.

"Swishing with water is a great way to just get some of that stuff off teeth," Rodriguez says.  "Also, sugar-free gum again after coffee, after sodas, anything that is either going to leave sugar on your teeth or leave potential staining on your teeth.  Just simple sugar-free gum, chewing it for 20 minutes, is really going to help clear a lot of that."