How to Tell If You Have a Cavity: 8 Symptoms You Shouldn’t Ignore

Updated: Mar. 14, 2022

Cavities are the second-most common health problem in the country, with over 3 million cases per year. You may not experience pain at all when a cavity first develops. However, you can experience the following cavity symptoms as it grows.

woman in pain lying down and holding her jaw

Persistent toothache and pain

How can you tell if you have a cavity? A toothache or severe pain often signal developing cavity symptoms, especially when the damaged tooth comes into contact with something. “Pain is often a symptom, and pain can be in the gums below the tooth or the tooth itself,” explains Eric Klein, a dentist in Norwalk, CT. “Sometimes you have a sharp, acute pain or it may be a dull, throbbing pain, and both are signs of a cavity.”

half-eaten red apple

Pain when chewing on food

“If you start chewing on any food and something hurts, it could be because the tooth has a crack in it or because the tooth has a cavity,” says Klein. If you feel a sharp, sudden pain after biting into an apple or chewing on food, the nerve in your tooth may be infected and in the process of decaying. Touching the afflicted area can help you gauge the severity of your pain and decide whether or not the tooth needs to be evaluated. If you can’t touch your tooth without shuddering in pain, schedule an appointment with your dentist to have the tooth examined. Here are some home remedies for toothaches you can try until you can get to a dentist.

smiling woman putting a piece of gum in her mouth
iStock/Eva Katalin Kondoros

Bad breath or a bad taste in the mouth

Cavities are essentially small, infected holes that develop in teeth, making them a perfect breeding ground for food particles and bacteria. “A cavity is caused by acid and sugar breaking a hole in the enamel, and then bacteria can get in that hole,” explains Klein. “Bacteria can cause odor and a bad taste in the mouth.” According to the American Dental Association, bad breath may also be a warning sign of gum disease, caused by a buildup on plaque on teeth that irritates the gums. If you notice persistent bad breath or a bad taste in your mouth, contact a dentist to further evaluate the bacteria’s source. These are other likely reasons you could have bad breath.

coffee pot pouring into a white cup and saucer
iStock/Robert Ingelhart

Increased sensitivity to temperature

According to statistics from the most recent National Health and Nutrition Examination Survey, 92 percent of adults ages 20 to 64 have had at least one cavity. If you’re one of them, you may have experienced a strange sensitivity to temperature in the infected tooth. Another way to tell if you have a cavity? You might have extreme sensitivity to hot or cold liquids and foods, making eating or drinking unpleasant and painful. “Every tooth has a nerve inside of it, and it also has blood supply to help the tooth grow and function,” says Klein. “When a cavity gets larger and closer to that nerve, it can sense the change in temperature easier.” Here’s how to tell if your cavity symptoms are actually signs you’re headed for a dental emergency.

cavity in person's back molar

Dark spots on the teeth and/or discoloration

While some cavities appear on the surface as holes, others look more like spots or stains on the surface of the infected tooth. According to the Mayo Clinic, black, brown, or white spots on teeth are often signs of tooth decay, though they can also be natural stains. If a spot is soft or sticky, it is likely a symptom of a growing cavity. In some cases, cavities may cause the entire tooth to darken and increase its likelihood to chip. If you notice spots or discoloration in your teeth, visit a dentist to have the stains evaluated. Follow these oral hygiene tips for white, healthy teeth.

man brushing teeth and looking in mirror

Bleeding when brushing

Cavities can cause bleeding when brushing due to gum irritation from the damaged nerve. Recurrent bleeding may be a sign of gum disorder or a symptom of a deep cavity. “If you have a big cavity at the gum line, you might catch food in the cavity and that can cause a gum issue,” explains Klein. “If you have a really big cavity, you can have blood that comes from the tooth.” Also, make sure you avoid these common toothbrushing mistakes.

man looking at dental X-ray

Swelling in certain parts of the gums

Sometimes, swelling of the gums are how to tell if you have a cavity, though the swelling may not necessarily be painful. “If you have a really deep cavity, it makes the nerve sick or die, and that causes an infection in a nerve that causes swelling,” says Klein. “Some people feel swelling and it doesn’t even hurt, but that’s caused from the infection.” Contact your dentist if you notice swelling in a specific area of the gums as this may be a sign of a cavity or gum infection.

man in business suit on airplane with hand on head

Pain due to changes in pressure

If you’ve ever experienced a toothache when taking off on an airplane or deep-water scuba diving, it might be due to a developing cavity. Changes in air pressure can irritate the nerve within an infected tooth, causing dull or severe pain and discomfort. If you feel an unfamiliar pain in these types of situations, have a dentist examine the tooth to catch the cavity before it grows. Filling a cavity during its early stages will prevent the decay from growing and lessen cavity symptoms. Next, check out these everyday mistakes that can ruin your teeth.

Reader's Digest
Originally Published in Reader's Digest