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Check the myths and facts below to find out how cavities are caused, prevented, and treated.

1. Sugar Is the Prime Cause of Cavities

Myth, but it's almost a fact. 

The truth is, acid produced by bacteria in your mouth is the cause of cavities, says Kimberly A. Harms, DDS, an American Dental Association consumer advisor and former president of the Minnesota Dental Association. However, these bacteria are triggered to make acid when you eat anything with carbohydrates -- and sugar is a carb.  

Rice, potatoes, bread, fruits, and vegetables are also carbs.

Once the acid eats into your tooth, the bacteria “have a nice little hole to live in where your toothbrush and floss can’t reach,” says Harms. The bacteria continue to metabolize carbs and produce acids -- and your cavity just keeps getting bigger.

Here’s an important fact. It’s not the amount of carbs you eat that causes tooth decay, but the length of time your teeth are exposed. If you eat a lot of carbs for lunch, that’s one big exposure. But if you spend the day sipping sugary drinks, that’s continuous exposure -- and much more unhealthy for your teeth.

“We have a saying,” says Harms. “Sip all day and get decay.”

2. Exposure to Acidic Foods, Like Lemons, Causes Tooth Decay

Fact. Acidic foods such as lemons, citrus juices, or soft drinks don’t cause cavities, but they may be putting your enamel in danger.

"Acids can tear down your enamel and weaken your tooth," says Harms. “If you lose the enamel's protection and expose the underlying dentin, your tooth is now more prone to decay.”

3. Kids Are a Lot More Likely to Get Cavities Than Adults

Myth. With the help of sealants, fluoridated water, and preventive care, “we’ve actually cut decay in school-aged children by half in the last 20 years,” says Harms.

However, there’s been an increase in cavities in senior citizens “because they have some unique circumstances,” she says. Some medicines dry out the mouth, for example, reducing salvia. Saliva is vital in fighting tooth decay because it helps neutralize acids, has a disinfectant quality, washes away bacteria, and helps prevent food from sticking to your teeth.

4. Aspirin Placed Next to a Tooth Will Help a Toothache

Myth. Swallowing aspirin is what helps reduce toothache pain. Since aspirin is acidic, placing it beside the tooth can actually burn your gum tissue, causing an abscess. "So don’t do it," says Harms. "Always swallow the aspirin!"

5. All Fillings Eventually Need Replacing

Myth. An amalgam or composite filling needs to be replaced if it breaks down or a cavity forms around it, or if the tooth fractures, says Harms. If none of those problems occur, you can keep the same filling for life.

“Fillings do have a life expectancy,” says Harms, but it depends on things like tooth wear and oral hygiene habits. If you brush your teeth twice a day with a fluoride toothpaste and floss and use a mouth rinse once a day, you’ll have less tooth decay and your fillings may last longer.

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