A cavity is a hole in the tooth. Cavities develop when bacteria inside the mouth produce acids that erode the hard enamel surface of the tooth. Over time, cavities can extend further into the softer layers of the tooth, causing pain.

Cavities are a symptom of tooth decay. Without treatment, they can lead to pain, infection, and tooth loss.

This article describes the signs, symptoms, and causes of cavities, and outlines some risk factors for developing cavities. We also provide some prevention tips and offer advice on when to see a dentist.

Lower half of a woman's face as she smiles, showing her teeth, which have no signs of cavities.Share on Pinterest
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The signs and symptoms of tooth decay depend on several factors, including the location and extent of individual cavities and the number of teeth affected.

Small, surface cavities may not cause any signs or symptoms to begin with. However, as the cavity progresses, a person may experience the following:

  • white spots on the surface of the tooth, indicating early tooth decay
  • brown or black spots on the surface of the tooth, indicating developing tooth decay
  • visible holes or dents in the tooth enamel
  • sensitivity or toothache in the area of the cavity
  • generalized toothache or jaw pain
  • pain during eating or drinking, especially with foods that are hot, cold, or sugary
  • pain when biting down or chewing on food

A dentist will look for signs of tooth decay during an oral examination and may recommend dental X-rays to help look for cavities between the teeth or behind fillings.

Individual teeth are composed of the following layers:

  • Enamel: The outermost layer of the tooth. It is composed of minerals that form a hard, smooth, protective surface.
  • Dentin: The middle layer of the tooth. It consists of tiny tubules that create the main structure of the tooth.
  • Pulp: The innermost layer of the tooth. It contains the nerves.

Plaque is a sticky film of bacteria that constantly forms on the surface of the tooth. Consuming sugary foods or beverages causes the bacteria to produce acids that attack and dissolve tooth enamel. Because plaque is so sticky, the acids can remain on the teeth for a long time. This can cause the enamel to break down or “demineralize,” resulting in a cavity.

Regular brushing and flossing help remove harmful plaque, while saliva can help neutralize and wash away acids. Together, these processes help teeth remineralize and repair damaged tooth enamel before a cavity forms.

Cavities are a common problem among both children and adults. According to the Centers for Disease Control and Prevention (CDC), 1 in 5 children aged 5–11 years and 1 in 7 aged 12–19 years has at least one untreated decayed tooth. The CDC also reports that more than 1 in 4 adults in the United States has untreated tooth decay, and around 96% of those over the age of 65 have experienced at least one cavity.

Anyone who has teeth is at risk of tooth decay and cavities. The following factors may increase the risk of cavities:

  • incorrect or irregular brushing or flossing
  • not visiting the dentist regularly for check-ups
  • not visiting the oral hygienist regularly for professional cleanings
  • frequently snacking on high sugar foods or sipping on high sugar beverages
  • eating certain foods that can cling to teeth, such as ice cream, sugary foods, and potato chips
  • not having enough fluoride, since fluoride can help to prevent cavities and reverse early signs of damage
  • medication that causes a dry mouth, since saliva helps neutralize and wash away harmful acids

Factors that increase the risk of cavities in children include inefficient brushing techniques and consuming more sweet foods. Factors that increase the risk for adults include having existing dental fillings that may leak or crack and having receding gums, which can expose the tooth root to decay.

Certain economic and social factors can also increase the risk of tooth decay and cavities. For example, difficulty maintaining oral health is more common among the following people:

  • older people who are on a low income and do not have medical insurance
  • children from low income households
  • Hispanic adults and non-Hispanic Black adults on low incomes and without access to appropriate dental care
  • people with chronic diseases that can increase the risk of oral health issues, such as diabetes, arthritis, or heart disease

Without treatment, cavities can extend into the deeper layers of the tooth. This may result in the following symptoms:

  • increasing pain
  • swelling around the affected area
  • an infection, or abscess, in the tooth and gums
  • problems eating, which may lead to malnutrition and weight loss
  • loss of part or all of the tooth
  • problems with self-esteem following tooth loss

In some instances, an oral infection can spread to the bloodstream. Medical professionals refer to this as septicemia. Without prompt and aggressive antibiotic treatment, septicemia can result in a potentially life threatening condition called sepsis. This condition involves widespread inflammation throughout the body and possible organ failure.

The American Dental Association (ADA) provides the following tips to help prevent dental cavities:

  • Regular brushing: People should brush their teeth twice a day using a fluoride toothpaste.
  • Regular flossing: People should clean between the teeth daily, using one of the following:
    • dental floss
    • a water flosser
    • an interdental brush
  • Regular dental visits: It is important that people attend regular dental check-ups, as a dentist can often identify early cavities before they become more problematic.
  • Regular oral hygiene visits: Regular visits to the oral hygienist can help to improve oral health.
  • Controlling diet: People should limit or avoid sugary snacks and drinks.
  • Taking supplements: A person can ask their dentist about supplemental fluoride to help strengthen the teeth. Supplements are available in the following forms:
    • tablets
    • lozenges
    • liquids
  • Receiving dental sealants: In some circumstances, dentists may place a dental sealant on the chewing surfaces of the teeth. A dental sealant is a thin, protective coating that helps stop bacteria from getting into tooth ridges and pits. According to the CDC, sealants protect the teeth from 80% of cavities for 2 years, and continue to protect against 50% of cavities for up to 4 years.

The ADA states that people should contact a dentist if they experience any of the following:

  • pain or swelling in the mouth, jaw, face, or neck
  • difficulty chewing or eating
  • swollen or bleeding gums
  • spots or sores in the mouth
  • dry mouth
  • a medical condition or medical treatment that may affect the teeth, such as:
  • pregnancy, as this can make some dental problems worse
  • self-consciousness due to the appearance of the teeth

Cavities are holes in the enamel surface of the tooth. Over time, cavities can progress to deeper layers of the tooth. Without treatment, this may result in pain, infection, and tooth loss.

Anyone who has teeth can develop cavities. However, factors that can help reduce the risk of dental cavities include regular brushing and flossing, regular visits to the dentist and oral hygienist, and preventive treatments, such as fluoride supplementation and dental sealants.

Anyone who experiences symptoms of dental decay or another oral health issue between dental check-ups should book an appointment with their dentist. Signs to look out for include swollen or bleeding gums, difficulty chewing, and pain in the tooth, jaw, or face. Prompt treatment can help prevent dental disease from worsening and causing other complications.