Have you heard the urban legend about what happens to a tooth when you leave it in a glass of Coke overnight?

Even if you don't have a theory -- and we'll tell you later if it's true -- you've probably heard or read some other recycled testimonial about the acidic powers of soda. It cleans car battery terminals. It wipes out the most stubborn blood and oil stains. It has the power to dissolve Satan on contact.

Urban legend Web site Snopes.com has devoted a broad and hilarious category to the topic.

Just because soda can't remove house paint doesn't mean we should drink as much as we do, however. According to a study by the American Dental Association, about one in every four beverages Americans consume is a soft drink. And the acid these drinks contain is far from harmless.

What Else Softens Teeth?

Most carbonated beverages contain phosphoric and citric acids that can harm the tooth's enamel. But soda isn't the only culprit.

"Anything that has a high acid content that's overused or abused or placed improperly in the mouth can cause tooth erosion," says Dr. Charles Perle of the Academy of General Dentistry.

Other enamel enemies include orange juice, tea, coffee, citrus fruits, pickles, wine and even yogurt. Sports drinks are also harmful. In fact, Perle says, most sports drinks have three to 11 times the acid content of soda.

The enamal is the hard outer coating of the tooth. Check out more about how teeth are made.

If that isn't enough to break your habit of gargling with Dr. Pepper every night before bed, chew on this: Enamel erosion is irreversible, Perle says.

"Your natural saliva will restore the enamel, but it takes a longer time. The acid in the soda works faster," he says.

While carbonated beverages are more damaging, you might want to reconsider your coffee consumption.

"Coffee's not as bad, but it depends. Are you putting a lot of sugar in it? If there's a lot of sugar, you're doing it again," Perle explains. "Sugar is high in acid."

Chugging, Food, Straws Protect

Fortunately, the preventive measures are relatively simple. If you drink coffee or tea, try to avoid constant sipping.

"We're talking about nursing it throughout the day," Perle says. "If you sip on a high-acid drink all day long, it's going to cause more problems than if you just drink it."

You should also try to consume the high-acid drinks with food. "Because when you're having food, and you're chewing, your saliva is active" and can help combat the acid, Perle explains.

Perle also suggests keeping soda and other cold drinks off the teeth by using a straw.

"If you take a straw and put it in the back of your mouth, keep it off your teeth, you're not going to damage your mouth," he says.

Water Is Best Defense

Drinking water is the best alternative, Perle says, but if you're not willing to make the switch, consider rinsing with it after consuming acidic foods or beverages.

And contrary to intuition, be sure to wait 20 to 30 minutes before brushing your teeth.

"The acid in the soda -- or even just eating a lot of fruit -- can cause a breakdown in the enamel structure," he says. "If people brush their teeth, the enamel is soft, and (brushing) can cause more problems."

Sugarless gum can be helpful after an acidic drink, too.

"If you're going to drink soda and you can't rinse your mouth out, you can chew sugarless gum to get the saliva flowing and get that soda off your teeth," Perle says.

He is quick to point out that despite all the warnings, a daily cup of herbal tea or can of pop won't ruin your teeth.

"I think the most important thing is overconsumption. You have to be careful of that," he says.

As for what actually happens when a tooth -- or a nail or a steak -- takes a soak in Coke, Snopes has the truth: "Much of the item will dissolve eventually, but after a day or two, you'll still have most of the tooth, a nail and one very soggy T-bone."