Cavities - How To Tell If You Have One - WebMD

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Written by WebMD Editorial ContributorsMedically Reviewed by Robert Brennan, DDS on August 03, 2025

• What Is a Cavity?
• Cavity Signs and Symptoms
• Cavity Causes and Risk Factors
• Cavity Diagnosis
• Cavity Treatment
• Cavity Prevention
• Cavity Complications

4 min read

What Is a Cavity?

A cavity is what you get from tooth decay -- damage to a tooth. Decay can affect the outer coating of a tooth (called enamel) and the inner layer (called dentin).

Cavity Signs and Symptoms

The symptoms of a cavity will depend on how large it is and where it is in your mouth. You may not have any symptoms at first. They’ll get worse as the cavity gets larger, including:

• Pain or a toothache that happens without warning

• Sensitive teeth

• Pain when you eat or drink sweet, hot, or cold things

• Holes or pits in your teeth

• Black, white, or brown tooth stains

• Pain when you bite down

Cavity Causes and Risk Factors

When foods with carbohydrates like bread, cereal, milk, soda, fruit, cake, or candy stay on your teeth, they cause decay. The bacteria in your mouth turn them into acids. The bacteria, acid, food debris, and your saliva combine to form plaque, which clings to your teeth. The acids in plaque dissolve the enamel, creating holes called cavities.

Many people think that only children get cavities, but changes in yourmouth as you age make them an adult problem, too. As you get older, your gums pull away from your teeth. They can also pull away because of gum disease. This exposes the roots of your teeth to plaque. And if you eat a lot of sugary or high-carb foods, you’re more likely to get decay and cavities.

Seniors often have a lot of dental work because they didn't get fluoride or good oral care when they were kids. Over the years, these fillings can weaken teeth and break. Bacteria gather in the gaps and cause decay.

If you have teeth, you’re at risk for cavities. Some things can raise your chances:

• Clingy foods and drinks. Foods like sugar, soda, milk, ice cream, cereal, and chips are more likely to stay put and cause decay.

• Poor brushing. When you don’t brush your teeth after eating and drinking, plaque and decay have a chance to form.

• A lack of fluoride. This mineral, found in toothpaste, mouthwash, and some tap water, helps to prevent cavities and can reverse early tooth damage.  

• Dry mouth. Saliva washes away food and plaque from your teeth and helps prevent tooth decay.

• Eating disorders. When you throw up over and over, stomach acid can dissolve teeth enamel, which may lead to cavities. 

• Acid reflux disease. This condition forces stomach acid into your mouth and wears down your teeth, causing cavities.

Cavity Diagnosis

Be sure to have regular checkups and cleanings, since that’s when your dentist finds cavities. They’ll probe your teeth, looking for soft spots, or use X-rays to look between your teeth.

Cavity Treatment

You may be in a lot of pain while waiting for your dental appointment. Ask your doctor if it’s OK to take over-the-counter pain medicine. You can also:

• Brush your teeth with warm water

• Use toothpaste made for sensitive teeth

• Avoid foods and drinks that are hot, cold, or sweet 

Treatment depends on how bad the cavity is. Most often, the dentist takes out the decayed portion of your tooth with a drill. There are a few options to repair the tooth:

• Filling. Your dentist will fill in the hole with a filling made of silver alloy, gold, porcelain, or a composite resin. These materials are safe. Some people have raised concerns about mercury-based fillings called amalgams, but the American Dental Association, the FDA, and other public health agencies say they’re also safe. Allergies to fillings are rare.

• Crowns. Dentists use crowns when a tooth is so badly decayed that there’s not much healthy enamel left. They’ll take out and repair the damaged part, then fit a crown made from gold, porcelain, or porcelain fused to metal over the rest of the tooth.

• Root canal. You might need a root canal if the root or pulp of your tooth is dead or injured in a way that can't be repaired. The dentist removes the nerve, blood vessels, and tissue along with the decayed portions of the tooth. They fill in the roots with a sealing material. You may need a crown over the filled tooth.

Cavity Prevention

You can prevent tooth decay and cavities with a few lifestyle changes:

• Brush twice a day with a toothpaste that has fluoride.

• Floss your teeth.

• Eat a balanced diet and cut down on snacking.

• Visit your dentist for regular checkups and cleanings.

Cavity Complications

A cavity may seem like a minor issue, but you should take it seriously. This is also true of children who don’t have their permanent teeth yet. Cavities can cause long-term problems including:

• Pain

• A pocket of pus caused by a bacterial infection (abscess)

• Tooth damage

• Trouble chewing

• Tooth loss

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