What to know before you try bleaching your teeth at home

With the availability of so many over-the-counter teeth-whitening products, anyone can flash a bright smile at an affordable price.

Kits or products cost $6 to $40 and come in strips, gels or tray applicators, which work as a mold around the teeth. Teeth whitening procedures through a dentist's office can cost hundreds or thousands of dollars.

So if you choose to take the less expensive, over-the-counter route, what kind of results should you expect?

"The results vary, but they last between one to six months," said R. Clark Goodwin, a dentist in Fayetteville, N.Y.

Goodwin said many people are obsessed with white teeth because of makeover shows and marketing. He said images from television, magazines and advertising always depict people with perfect smiles.

"I hate to say it's a very superficial world, but it is very superficial," Goodwin said. "My philosophy is, we're in the days of modern medicine where it's not unheard of to live to be 90 years of age. If you're going to live to be 90, you might as well live with a nice smile."

The kits and products you buy at a drug or grocery store can be effective, affordable and easy to use, according to Goodwin.

But there are disadvantages:

• Be prepared to repeat the whitening process with kits and products you buy over the counter, since the whiteners usually don't last very long. Goodwin said a dentist can prescribe stronger chemicals that can keep your teeth white for six months to one year.

• Over-the-counter products do not work on caps, crowns, veneers, dentures or fillings.

• Most tray kits work as one-size-fits-all, which might not work with all shapes and sizes of teeth. On the other hand, a dentist customizes trays specifically for your mouth shape.

How do they work?

Carbamide peroxide and hydrogen peroxide are the two main ingredients that bleach the tooth enamel, Goodwin said. Over-the-counter products contain 10 to 22 percent of peroxide, according to the American Dental Association. Goodwin said a dentist can use products with 15 to 40 percent peroxide.

Is bleaching teeth safe?

If you follow the instructions and don't go overboard, bleaching does not harm your teeth, according to Terrence J. Thines, chief of division of dentistry at SUNY Upstate Medical University in Syracuse, N.Y.

Thines said the bleach can reduce surface stains from food, beverages or cigarettes, but not deeper blemishes within the tooth. For example, antibiotics such as tetracycline can causes permanent discoloration on the teeth that whiteners do not change.

What if you bleach too much?

Bleaching your teeth too much can cause permanent discoloration, damage to the tooth's root and gum sensitivity, according to Thines.