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Tooth decay
Tooth decay

Tooth decay is damage to a tooth caused by dental plaque turning sugars into acid.

What causes tooth decay

Your mouth is full of bacteria that form a film over the teeth called dental plaque.

When you consume food and drink high in carbohydrates, particularly sugary foods and drinks, the bacteria in plaque turn the carbohydrates into energy they need, producing acid at the same time.

The acid can break down the surface of your tooth, causing holes known as cavities.

Once cavities have formed in the enamel, the plaque and bacteria can reach the dentine, the softer bone-like material underneath the enamel.

As the dentine is softer than the enamel, the process of tooth decay speeds up.

Without treatment, bacteria will enter the pulp, the soft centre of the tooth that contains nerves and blood vessels.

At this stage, your nerves will be exposed to bacteria, usually making your tooth painful.

The bacteria can cause a dental abscess in the pulp and the infection could spread into the bone, causing another type of abscess.

Symptoms of tooth decay

Tooth decay may not cause any pain.

But if you have dental caries, you might have: 

  • toothache – either continuous pain keeping you awake, or occasional sharp pain without an obvious cause; it can sometimes be painless
  • tooth sensitivity – you may feel tenderness or pain when eating or drinking something hot, cold or sweet
  • grey, brown or black spots appearing on your teeth
  • bad breath
  • an unpleasant taste in your mouth

Managing tooth decay at home

During the COVID-19 (coronavirus) pandemic, routine dental services are not currently available and any urgent dental treatment options are limited (e.g. extraction of teeth). When normal dental services resume, visit your dentist regularly so early tooth decay can be treated as soon as possible and the prevention of further decay can begin. 

In the meantime you can manage tooth decay and holes in teeth at home by:

  • reducing how much and how frequently you have sugary foods and drinks
  • brushing your teeth at least twice a day with fluoride toothpaste
  • using a temporary filling kit, available at supermarkets and pharmacies to temporarily fill the hole until you are able to see your dentist again
  • avoiding things that make the tooth sensitive or painful such as hot, cold or sweet food or drinks

If your toothache worsens despite using painkillers and taking other measures call your dental practice by telephone and they can provide further advice. If you do not have a regular dentist you need to call the appropriate dental helpline number for your Local Health Board area.

If you believe or know you have COVID-19 and have a dental emergency, please phone NHS 111 Wales.


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Selected links

NHS 111 Wales links

Dental Symptom Checker


Root canal

External links

Oral Health Foundation

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The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website
Last Updated: 29/06/2020 15:42:33