Tooth decay is the process that results in a cavity (dental caries). It occurs when bacteria in your mouth make acids that eat away at a tooth. If not treated, tooth decay can cause pain, infection, and tooth loss.

See pictures of a tooth  and tooth decay .

You can easily prevent tooth decay by brushing and flossing your teeth regularly, seeing your dentist for teeth cleaning and checkups, and avoiding foods that are high in sugar.

What causes tooth decay?

The combination of bacteria and food causes tooth decay. A clear, sticky substance called plaque that contains bacteria is always forming on your teeth and gums. As the bacteria feed on the sugars in the food you eat, they make acids. The acids attack the teeth for 20 minutes or more after eating. Over a period of time, these acids destroy tooth enamel, resulting in tooth decay.

What are the symptoms?

Tooth decay usually does not cause symptoms until you have a cavity or an infected tooth. When this occurs, a toothache is the most common symptom.

How is tooth decay diagnosed?

Your dentist diagnoses tooth decay by:

• Asking questions about your past dental and medical problems and care.
• Examining your teeth, using a pointed tool and a small mirror.
• Taking X-rays of your teeth and mouth.

How is it treated?

Treatment for tooth decay depends on how bad it is. You may be able to reverse slight tooth decay by using fluoride. To fix cavities caused by mild tooth decay, your dentist will fill the cavities with another substance (fillings). For more severe tooth decay, you may need a crown or root canal. In extreme cases, your dentist may have to remove the tooth.