What are cavities?

Cavities occur as a result of tooth decay. Tooth decay is the destruction of tooth structure. Tooth decay can affect both the enamel (the outer coating of the tooth) and the dentin layer of the tooth (see diagram) and in some cases extend into the pulp (nerve).

Tooth decay occurs when foods containing carbohydrates (sugars and starches) such as breads, cereals, milk, soda, fruits, cakes, or candy are left on the teeth. Bacteria that live in the mouth digest these foods, turning them into acids. The bacteria, acid, food debris, and saliva combine to form plaque, which clings to the teeth. The acids in plaque dissolve the enamel surface of the teeth, creating holes in the teeth called cavities, or caries.

Anatomy of a tooth | Cleveland Clinic

Who gets cavities?

Many people think cavities affect children only, but changes that occur with aging make cavities an adult problem, too. Recession of the gums (a pulling away of gum tissue from the teeth), often associated with an increased incidence of gum disease, can expose tooth roots to plaque. Also, sugary food cravings in pregnant women can make them more vulnerable to developing cavities.

Decay around the edges of fillings is also common in older adults. Because many older adults lacked the benefits of fluoride and modern preventive dental care when they were growing up, they often have a number of dental fillings. Over the years, these fillings may weaken and can fracture, allowing bacteria to accumulate in the tiny crevices and cause tooth decay.

Last reviewed by a Cleveland Clinic medical professional on 05/02/2017.


  • Mouth Healthy. American Dental Association. Decay Accessed 6/1/2017.
  • Klein U. Chapter 16. Oral Medicine & Dentistry. In: Way WW, Hay WW, Levin MJ, Sondheimer JM, Deterding RR, eds. CURRENT Diagnosis & Treatment: Pediatrics. 20th ed. New York: McGraw-Hill; 2011.
  • US Department of Health and Human Services. Take Care of Your Child’s Teeth. Accessed 6/1/2017.
  • American Academy of Family Physicians. Dental Hygiene: How to Care for Your Child's Teeth Accessed 6/1/2017.

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