What is a cavity?

Share this article

Cavities, also called dental caries, are holes in your teeth.

Cavities that are left untreated will continue to get bigger and deeper until they reach the root of your tooth. The hole in the tooth becomes a breeding ground for bacteria that can cause infections. To stop the spread of a cavity, a dentist may be able to repair it with fluoride. If the cavity is deeper, a dentist will need to clean out the hole and get rid of all the bacteria and debris, then fill the hole and patch it so that the bacteria stays out.¹

Cavities are common in adults. About 90% of adults between the ages of 20 and 64 have dental caries.² Over 80% of people experience at least one cavity before the age of 34.³ Cavities that aren’t repaired can lead to tooth loss, broken teeth and in severe cases, abscesses in gums that can require swift medical intervention.⁴ Even if you aren’t experiencing a lot of pain from a cavity, it’s best to get it taken care of right away.

A background decorative of Blue color

Symptoms of a cavity

The signs of a cavity vary depending on their severity and location. When a cavity is forming, you may not experience any symptoms. As a cavity grows, it may cause toothaches, tooth sensitivity, pain when eating or drinking, visible holes or pits in your teeth or stains on the surface of your teeth.⁵

A cavity that is new or just starting will look like a small white spot or dot on a tooth. As the cavity advances, it will look tan or brown, and finally it will look like a black spot on your tooth.⁶ It can be difficult to spot cavities until they are very advanced, but a dentist or hygienist may be able to spot a cavity that is just starting. A cavity will feel like a small hole or abrasion on your tooth. If you run your tongue over the tooth and there is an advanced cavity, you can feel the dip or hole in the tooth.

A cavity can occur in any tooth, but most of the time it’s back teeth and hard to clean teeth that develop cavities. There are two types of cavities that are common:⁷

  • Coronal cavities: Coronal cavities are cavities that occur on the chewing surfaces of your teeth. They’re the most common type of cavity and are generally easy to fix if they are caught quickly.

  • Root cavities: Root cavities are more serious and more painful. They occur when receding gums leave part of the tooth exposed. Abscesses in root cavities can be very serious and painful.

What causes cavities?

Cavities are caused by plaque. Plaque is that sticky film that forms on your teeth that makes your teeth feel fuzzy or thick. Plaque is made up of bacteria, food debris, and acid from the foods and drinks that you have. It can be very difficult to remove plaque from your teeth but regular brushing and flossing can remove a lot of plaque, which is one of the reasons why good oral hygiene is essential to prevent cavities.⁸

Everyone has plaque. But there are some people that are more prone to developing plaque. Lifestyle and dietary habits also play a role in how much plaque you have. Some of the factors that influence how much plaque you have are:⁹

  • Dietary habits - Your dietary habits have a big impact on your dental health, including on the development of cavities. Eating a lot of sugary or starchy foods or drinking sugary drinks like sports drinks, sodas or juices can contribute to the plaque that develops in your mouth. The bacteria in your mouth feeds on sugar and starch so the more sugar and starch you eat the more bacteria you will have in your mouth that can end up attacking your teeth. Acidic foods and drinks contribute to tooth decay also.

  • Oral hygiene - Your oral hygiene is another important element that can determine if you get cavities. Brushing and flossing will get rid of that plaque and protect your teeth. But you have to brush your teeth thoroughly for at least two minutes at least twice a day. Not brushing your teeth often, not doing a good job when you do brush your teeth, and not using a good quality toothpaste when you brush can all influence how many cavities you get.

  • Dry mouth - Dry mouth is a very common problem. It can be seasonal, depending on the climate that you live in. Or it can be caused by certain medications that you take for other health problems. When your mouth isn’t making enough saliva to wash away bacteria and food debris that bacteria and food debris become plaque.

  • Fluoride - If you aren’t getting enough fluoride your teeth can become weak and brittle and more prone to cavities. Fluoride keeps the enamel on the tooth strong so that plaque has a tougher time getting through it.

Treatment for a cavity

The treatment for a cavity is fairly simple and straightforward. The dentist will drill down into your tooth, clean out all the plaque and debris, then fill the tooth with either an amalgam or composite filling.¹⁰ Once the filling is in you shouldn’t have to worry about that tooth developing a cavity again.

Links to external sites are provided for your convenience in locating related information and services. Guardian, its subsidiaries, agents and employees expressly disclaim any responsibility for and do not maintain, control, recommend, or endorse third-party sites, organizations, products, or services and make no representation as to the completeness, suitability, or quality thereof.

Brought to you by The Guardian Life Insurance Company of America (Guardian), New York, NY. Material discussed is meant for general illustration and/or informational purposes only and it is not to be construed as tax, legal, investment or medical advice. It is not dental care advice and should not be substituted for regular consultation with your dentist. If you have any concerns about your dental health, please contact your dentist's office.


  1. https://www.mouthhealthy.org/en/dental-care-concerns/how-do-we-prevent-cavities (Last accessed March 2020) 

  2. https://www.nidcr.nih.gov/research/data-statistics/dental-caries/adults, 2018

  3. https://www.cdc.gov/oralhealth/basics/index.html, 2019 

  4. https://www.mayoclinic.org/diseases-conditions/cavities/symptoms-causes/syc-20352892, 2017

  5. https://www.mayoclinic.org/diseases-conditions/cavities/symptoms-causes/syc-20352892, 2017

  6. https://www.mouthhealthy.org/en/dental-care-concerns/how-do-we-prevent-cavities (Last accessed March 2020) 

  7. https://www.colgate.com/en-us/oral-health/conditions/cavities/what-are-cavities (Last accessed March 2020) 

  8. https://www.mayoclinic.org/diseases-conditions/cavities/symptoms-causes/syc-20352892, 2017

  9. https://www.mayoclinic.org/diseases-conditions/cavities/symptoms-causes/syc-20352892, 2017

  10. https://health.ri.gov/oralhealth/about/fillingmaterials/ (Last accessed March 2020)


Insights for the people.

Join our new digital insurance community that includes tips, resources and useful information from Guardian Direct.