How To Tell If You Have A Cavity

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Wondering how to tell if you have a cavity?

Do your teeth feel sensitive? Do you have some sort of discomfort or pain when you bite? If yes, then you should probably see your dentist as these could be signs of a cavity.

Cavities happen to everyone. The data from the National Institute of Dental and Craniofacial Research (NIDCR) says a whopping 92% of adults in the United States have this problem, and 26% of adults suffer from untreated tooth decay. Most of the time, these cavities are just sitting in the mouth waiting to be filled, and people don’t have any idea about their existence. But what is a cavity really? More importantly, how to tell if you have a cavity?

What is a Cavity?

A cavity is a permanently damaged area on the surface of the teeth. It is characterized by tiny openings or holes. It happens in both the outer coating of the tooth (enamel) and the inner layer (dentin). You get cavities from tooth decay; this is why it is also often called tooth decay or caries.

Causes and Risk Factors

The bacteria inside your mouth feed on food high in carbohydrates like bread, cakes, cereals, fruits, milk, soda, etc. They turn this trapped food debris into acid. Combined with your own saliva, these things cling to your teeth and forms plaque. When dissolved on your enamel, plaque creates tiny holes called cavities.

Since children eat candies and sweets the most, most people assume only the young ones get cavities. However, your mouth changes as you age, and as you grow older, your gums start to pull away from your teeth. Poor dental hygiene can also cause gum disease which exposes the roots of the teeth, making them vulnerable to plaque. If you eat lots of high-carb and sweet sugary foods, then there’s a higher chance you get cavities.

Subsequently, older adults with tooth fillings get decays caused by cavities around the edges of the fillings. Bacteria gather in these gaps causing further decay, leading to weakening and breaking of the teeth.

Other risk factors that cause cavities include:

  • Sweet sugary drinks and clingy food – Candies, ice cream, and even chips, sodas, and milk are likely to cling to your teeth, giving bacteria the opportunity to cause decay
  • Poor dental habits, bad brushing technique – While brushing after every meal is necessary, doing proper brushing technique is as important. When brushing, make sure to brush the outer, inner, and chewing surfaces of the teeth. Also, tilt the brush vertically and do several up-and-down strokes to clean the inside surfaces of the teeth.
  • Dry mouth – Saliva helps in washing away trapped food debris and plaque from your teeth. Thus, it is important to stay hydrated all the time.
  • Not getting enough fluoride – Fluoride is the primary mineral found in most toothpaste, mouthwash, and even tap water. It helps prevent cavities or even reverse the early stages of tooth damage.
  • Eating disorders – When you throw up, stomach acid can get trapped in between your teeth and can cause damage to the enamel, which often leads to cavities.
  • Acid reflux disease – This condition forces acid from the stomach to go up into your mouth. Again, stomach acid is harsh and harmful to your teeth. Eating highly acidic and fatty food is the most common cause of acid reflux, as well as spicy foods and certain medications like aspirin, ibuprofen, some sedatives, and other blood pressure medications.

Tell-tale signs you have a cavity

The signs and symptoms of the cavity largely depend on how big the problem is and where it is located inside your mouth. There are cases where you may not see or experience any symptoms at first, but as the problem develops, the cavities get larger and the problem gets worse.

Tooth sensitivity (especially to heat and cold)

This is probably the most common and early symptom that a cavity is lingering inside your mouth. While occasional tooth sensitivity isn’t a cause of alarm in many cases, consistent sensitivity to hot or cold food or beverages, especially if you haven’t had any recent dental work done on your teeth is a tell-tale sign of a cavity.

When the enamel of your teeth wears down, the dentin (inner layer of your teeth) gets exposed. This layer contains microscopic hollow tubes that are sensitive to the outside temperature. Thus, when hot or cold food or beverage hits this layer, it stimulates the nerves in your teeth, creating that weird feeling of discomfort and sensitivity.

The feeling of sensitivity may linger for a few seconds or could last for a few minutes after you have food or beverage. Thus, this makes eating or drinking the foods you usually enjoy quite challenging.


Another classic sign of cavity is toothache.

While occasional toothache can be normal, consistent and nagging pain is not. Toothache can sometimes be caused by erupting or irritated tooth, or a cracked tooth that went unnoticed.

Toothache can range from dull and occasional to debilitating and consistent pain. It can be random or after you eat something your cavity doesn’t like. The pain could be isolated in a certain area in your mouth or can radiate around to multiple teeth. Toothache can also make biting down food quite painful.

Toothaches occur when there’s an inflammation around the affected tooth. This happens when the exposed dentin becomes too sensitive, causing pain. Also, chipped or cracked teeth can also cause cavities.

If you have been experiencing consistent pain, then it is best to visit your dentist.

Teeth discoloration

Since the cavity is a symptom of tooth decay, a cavity that has gone bad leads to physical changes of the teeth – i.e. discoloration.

A set of healthy teeth has an off-white coloring (pearly white if you’ve had dental whitening treatment or other dental cosmetic services). Dark spots around your teeth, however, (be it brown, black, or purple) are a tell-tale sign of a cavity. It is important to watch out for these spots, especially if they grow in size. A spot may start as a slight discoloration but as the cavity develops, it can turn into a darker and unappealing color.

Holes and other visible marks

Like discoloration, visible holes and markings are also a clear indication of a tooth cavity gone badly. This is because as the damage progress, it eventually breaks down the teeth causing holes to grow in size making them more visible. You might notice these holes when you look closely in the mirror, or simply feel them with your tongue.

Pink toothbrush

If you notice some pink color in your toothbrush while brushing, that means you have bleeding and swollen gums.

Some cavities form near the gum line. When you brush your teeth, these cavities may get irritated and inflamed, causing bleeding. Bleeding and swollen gums aren’t always painful though, that is why you only notice it when you are brushing your teeth.

Healthy gums look pink. When they turn into a darker red or pale pink (almost white), then it means something is wrong and you need to visit your dentist for a checkup.

Weird taste and bad breath

As said earlier, bacteria feast on the trapped food in your mouth. As they consume these tiny bits of carbs and sugar, they produce waste, and their waste causes an unpleasant effect in your mouth – i.e. bad breath.

Like tooth sensitivity and pain, bad breath is common and not usually a cause of alarm. Most people experience “morning breath” and anyone who eats aromatics and spices in their food will have this dilemma.

However, if you notice your breath consistently smells bad, and if you notice some foul copper taste in your mouth lately, then there’s a good chance you have cavities. Whether your coworkers notice or it’s only you, the problem can get worse as the cavities progress.

Subsequently, the copper taste in your mouth is probably the blood from your gums. Gum disease can cause irritation to the gums that lead to bleeding.


If you regularly experience a severe and throbbing toothache that radiates all the way to the jawbone, neck, and ear, and you notice shiny swellings that protrude out of your gums that are sensitive to touch, then there’s a high chance the cavity has gone too bad and you have developed tooth abscess.

A tooth abscess is a result of an untreated dental cavity that has gone too far. It will pocket pus which is routinely collected and drained from the abscess. This can be extremely painful. Sometimes, it can lead to fever and swollen glands.

Pus in your gums is a serious problem, and you should visit your dentist right away as you may be needing antibiotics and get the cavities filled up to fix the problem.

No signs at all

Most of the time cavities can start really small and will have no noticeable signs or symptoms. Also, sometimes the teeth can repair mild and early stages of cavities. Proper dental hygiene and regular use of fluoride can help delay the progress of cavities.

This is why it is extremely important to visit your dentist regularly – to stop cavities on their tracks and keep your teeth strong and healthy!

How to Tell if You Have a Cavity: Conclusion

Now that you know how to tell if you have a cavity, you can use the information to determine when it is time to visit your dentist. Ideally, you need to check with your dentist as soon as possible when you exhibit one or more of these symptoms. Whether you have cavity, tooth decay, or something else, the sooner you can address the problem, the sooner you can also restore your dental health.

Dr Febin Mary George - Editor

With more than 10 years as a dental surgeon, Dr Febin Mary George is passionate about educating consumers around the world to help look after their teeth.

She completed her Bachelor of Surgery at the Century Institute of Dental Science and Research Centre in 2010.

Alongside editing the International Journal of Dental Clinics she has also written for major publications including Thrive Global.