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Tooth decay

3-minute read

Tooth decay occurs when a hole (cavity) forms in your tooth. It can affect people of all ages and even very young children. Having tooth decay can affect your health and lead to other conditions. However, tooth decay can be prevented or treated.

What causes tooth decay?

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

Stages of tooth decay

The acid from plaque attacks your enamel, which is the outer layer of your 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 your enamel. Repeated attacks will lead to a decay in the tooth.

How to prevent tooth decay

Tooth decay can be prevented by practising good dental care. This includes:

  • having sweet foods and sugary drinks only occasionally and, if possible, only at mealtimes
  • brushing your teeth twice a day with a fluoride toothpaste
  • 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

Treatment of tooth decay

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.

When to see a dentist

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

See your dentist as soon as possible if you have:

  • a toothache
  • tooth sensitivity (eg to hot or cold food or drinks)
  • brown, black or white stains on your tooth surface
  • pain on biting

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

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Last reviewed: January 2019

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