15 Myths and Facts About Cavities

You've probably been told since you were a kid to do everything you can to avoid cavities. But if you're like most of us, you may still be a bit hazy on the facts about tooth decay. Learn how to separate truth from fiction and you'll be on your way to a trouble-free smile.

1. Myth: Sugar Is the Only Thing That Causes Cavities

"The truth is, acid produced by bacteria in your mouth is the cause of cavities," says Kimberly A. Harms, DDS, an American Dental Association spokeswoman.

Any carb you eat can start that process. That includes sugar as well as rice, potatoes, bread, fruits, and vegetables.

2. Fact: Acid Causes Tooth Decay

Acidic foods can break down your teeth's outer shell (called the enamel), weaken the tooth, and make teeth more likely to decay.

"The bacteria responsible for tooth decay produces acids," says Misty Horn-Blake, DDS, a dentist in Johnson City, TN. "Eating acidic foods often throughout the day (including juice and soda) can enhance that process."

So go light on the acid and practice good oral care.

3. Myth: Kids Get Way More Cavities Than Adults

Thanks to fluoride in tap water, "we've actually cut decay in school-aged children by half in the last 20 years," Harms says.

On the flip side, she says cavities in senior citizens are on the rise because of medicines that dry out the mouth. They reduce saliva, which protects your teeth.

4. Myth: Aspirin Next to a Tooth Will Help a Toothache

You have to swallow the aspirin to ease your pain. Since aspirin is acidic, it could burn your gum tissue and cause a painful ulcer if you place it next to a tooth.

5. Myth: All Fillings Will Need to Replaced

"Fillings do have a life expectancy," Harms says, but it depends on things like tooth wear and oral hygiene.

If you keep up with your dental routine, you're less likely to have problems, and your fillings may last longer.

6. Myth: You'll Know When You Have a Cavity

"Sometimes you will know it, but at that point, it has usually spread to larger proportions than it would have if it had been found at a routine dental screening," Horn-Blake says.

With timely checkups, your dentist can find a cavity before it causes pain.


7. Fact: Once a Tooth Is Treated, the Decay Stops

After your dentist fills a cavity, the decay at the spot comes to a halt. But if you don't take care of your teeth, a new cavity may develop next to the filling or even around it. 

8. Fact: Cavities Are More Likely Between Teeth

"Anywhere bacteria can hide that you can't, or aren't able to, reach with a toothbrush or floss is a likely place for decay," Harms says.

Use a mouthwash to help get to tough spots.

9. Myth: Clenching and Grinding May Lead to Cavities

It may be a myth, but it's too not far from fact. Cavities come from acid-producing bacteria. But clenching and grinding are among the worst things you can do to your teeth, Harms says.

With normal chewing, teeth touch for a tiny fraction of a millisecond, which causes little stress. But clenching and grinding put a huge amount of pressure on your teeth. The strain can wear away the enamel, leaving it more vulnerable to decay.

Also, when you clench and grind, it can cause your gums to recede, exposing the roots of the teeth. They are more likely to decay.

10. Myth: Gaps in Teeth Lead to Cavities

"Bigger gaps are easier to keep clean," Harms says. So as long as food doesn't get stuck in the gap when you eat and deposit bacteria, wide spaces are less likely to decay.

Keep an eye on small gaps, though. Food may get stuck there and lead to cavities if it's not cleaned out.

11. Fact: Chips and Cracks in Teeth Lead to Decay

They create a home for bacteria where your toothbrush won't reach. This can speed up decay. Use a fluoride mouth rinse to reach hidden spots.

12. Myth: Sensitivity in Teeth Means You Have Decay

"While cavities can cause some sensitivities to cold and sweets, not all do," Horn-Blake says. Other things might be making your teeth hurt.

13. Myth: Cavities Are the Only Reason for Root Canals

You need a root canal if the nerve inside a tooth is damaged. An unfilled cavity can lead to a root canal, but so can other things, like clenching and grinding and injury to the tooth.


14. Myth: Babies Can't Get Cavities

Baby teeth can get cavities that spread to other teeth if left untreated.

15. Fact: You Have to Brush, Floss, and Rinse to Prevent Cavities

"Absolutely! Prevention is the key," Harms says. You need to remove bacteria from teeth.

Brush twice a day with a fluoride toothpaste, and floss and rinse every day. If you remove bacteria each day from every area of your tooth, "you won't get cavities," Harms says.

WebMD Feature Reviewed by Michael Friedman, DDS on June 22, 2016



Kimberly A. Harms, DDS, consumer advisor, American Dental Association; past president, Minnesota Dental Association.

CDC: "Carbohydrates."

Misty Horn-Blake, DDS, Tennessee.

American Dental Association: "Tooth Decay (Cavities/Caries)," "Mouthrinses," "Fluoride and Fluoridation."

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