Dental Caries (Tooth Decay): The NIDCR Patient Overview

Tooth decay is the destruction of tooth structure. It can affect both the enamel (the outer coating of the tooth) and the dentin layer of the tooth. 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.

Dental caries is one of the most common chronic diseases in the United States across the lifespan.

• About 90% of adults aged 20 to 64 have had at least one cavity.
• About 1 in 4 adults has untreated tooth decay at any given time.
• More than half of children aged 6 to 8 have had a cavity in their primary or permanent teeth.
• Children from lower-income families experience tooth decay at about twice the rate of children from higher-income families.

Tooth decay usually does not cause symptoms until you have a cavity or an infected tooth. When this occurs, you may experience:

• A toothache, which is the most common symptom
• Swelling in your gums near a sore tooth
• Bad breath or a foul taste in your mouth
• Broken teeth
• Brown, white, or black staining on the surface of a tooth

If you experience a toothache, see a dentist as soon as possible. Cavities can lead to a serious infection, but routine dental visits can find cavities early — before they cause serious problems.

The mouth is full of bacteria — some helpful, some harmful. Research has shown that certain types of bacteria stick to the enamel of your tooth. These bacteria build up into a sticky, colorless film called plaque.

Plaque on your teeth produces acid that can erode tooth enamel and cause tooth decay. If plaque is not removed by regular brushing, flossing, and dental visits, it can harden into tartar (also called calculus). Tartar is much harder to remove and can lead to gum disease.

In addition to a diet high in sugars, factors that contribute to tooth decay include:

• Inadequate brushing and flossing
• Insufficient fluoride exposure
• Dry mouth (which can be caused by certain medications)
• Eating disorders such as anorexia and bulimia
• Acid reflux disease that exposes the teeth to stomach acid

Everyone is at risk for cavities, but certain groups have a higher risk. This includes:

• Children and older adults — though dental caries can affect anyone
• People who consume a lot of sugary or starchy foods and drinks
• People who live in communities without fluoridated water
• People with poor oral hygiene (those who don't brush or floss regularly)
• People with dry mouth, often due to medications or certain medical conditions
• People who have eating disorders
• People who have acid reflux disease

The best way to prevent tooth decay is to follow these recommendations from NIDCR and the American Dental Association:

Brush twice daily with fluoride toothpaste

Fluoride strengthens the enamel and helps reverse early decay. Brush gently for at least two minutes, twice a day. Use a soft-bristled toothbrush and replace it every three to four months — or sooner if the bristles are frayed.

Clean between your teeth daily

Use dental floss or another between-teeth cleaner (such as a water flosser or interdental brush) to remove plaque from places your toothbrush can't reach.

Eat a balanced diet and limit between-meal snacks

Foods that contain sugar or starch — especially sticky candy, dried fruit, and sugary drinks — increase the time bacteria in your mouth can produce acid. Choose tooth-friendly snacks such as cheese, raw vegetables, plain yogurt, or fruits.

Visit your dentist regularly for professional cleanings and oral exams

Your dentist can spot decay in its earliest stages and help you address risk factors specific to your mouth.

Consider dental sealants

Sealants are thin protective coatings applied to the chewing surfaces of back teeth — the teeth most likely to develop cavities. School-age children without sealants have nearly three times more cavities than those with sealants.

Treatment for a cavity depends on how severe it is.

• Early decay (where the enamel is just beginning to demineralize) may be reversed with fluoride treatments such as professional fluoride varnish, fluoride toothpaste, or prescription fluoride rinses.
• Cavities that have formed typically require a filling. The dentist removes the decayed tooth tissue and replaces it with a filling material such as composite resin, amalgam, glass ionomer, or porcelain.
• Larger areas of decay that compromise a tooth's structure may require a crown — a custom-fitted covering that replaces the entire natural crown of the tooth.
• Decay that has reached the pulp (the inner soft tissue of the tooth) may be treated with a root canal, in which the infected pulp is removed and the tooth is sealed.
• A tooth that is too damaged to repair may need to be extracted and replaced with a bridge, implant, or partial denture.

Tooth decay is largely preventable. With good oral hygiene, a tooth-friendly diet, regular dental care, and access to fluoride, most people can avoid the pain, expense, and tooth loss that untreated cavities can bring.

This article is adapted from public-domain content published by the U.S. National Institute of Dental and Craniofacial Research (NIDCR) and the National Institutes of Health (NIH).