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Tooth decay

4-minute read

What is tooth decay?

Tooth decay occurs when a hole (cavity) forms in a tooth. It can affect people of all ages and even very young children.

Tooth decay is a disease that can cause pain and infection. In children, it can affect development, nutrition, speech and jaw development. As many as half of children under 6 in Australia have untreated decay in their baby teeth.

However, tooth decay can be prevented or treated.

What are the stages of tooth decay?

The acid from plaque attacks the enamel, which is the outer layer of the tooth. Repeated attacks of acid wear the enamel layer away. Tooth decay symptoms often begin with a white spot, usually near the gum line.

Left untreated, this can become a hole or cavity. If the cavity is not treated, the decay can get deeper into the tooth and cause a toothache or an abscess. In the later stages of decay, the tooth looks yellow-brown or black.

Illustration showing the stages of tooth decay.
Tooth decay starts with the acid from plaque attacking the enamel. Repeated attacks will lead to a decay in the tooth.

What are the symptoms of tooth decay?

If tooth decay is not treated, it can cause:

  • a toothache
  • tooth sensitivity (for example, to hot or cold food or drinks)
  • brown, black or white stains on the tooth surface
  • pain on biting
  • red and swollen gums
  • swollen face

CHECK YOUR SYMPTOMS — Use the teeth and dental problems Symptom Checker and find out if you need to seek medical help.

What causes tooth decay?

Tooth decay is caused by plaque — a sticky layer of germs — in the mouth. The germs in plaque turn the sugar in food and drinks into acid, which can gradually damage the teeth.

You are more likely to have tooth decay if:

  • you have gum disease
  • you have crooked teeth, meaning they are harder to clean
  • you smoke
  • you take medication that causes a dry mouth, such as asthma medication
  • you have had trauma to your gums or teeth

When should I see my dentist?

Because you can have tooth decay without any symptoms, you should visit your dentist regularly since they will check for tooth decay.

You can find a dentist at the Australian Dental Association website.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

ASK YOUR DENTIST — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

Can tooth decay be prevented?

Tooth decay can be prevented by:

  • brushing teeth twice a day for 2 minutes using fluoride toothpaste
  • having sweet foods and sugary drinks only occasionally — water is the best drink
  • eating a healthy, balanced diet
  • limiting or avoiding sugary snacks
  • having regular dental check-ups — many dental health experts recommend an appointment every 6 months

Children's teeth have softer and thinner enamel, so they decay more easily than adult teeth do.

If you have young children, you can help prevent decay in their teeth by:

  • cleaning their teeth twice daily
  • avoiding sugary drinks, such as juices, and sweet food
  • keeping your own teeth and gums clean and healthy to avoid passing decay-causing germs when you share spoons or taste their food

How is tooth decay treated?

Treatment in the early stages can stop or even cure tooth decay.

If it is mild, tooth decay can be treated by using fluoride and taking preventive steps. In some cases, your dentist might recommend that you have a special layer (sealant) applied to healthy back teeth to prevent tooth decay.

You might need a filling to restore your tooth structure.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: January 2021


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