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

If plaque is allowed to build up, it can lead to problems, such as holes in the teeth (dental caries) and gum disease.

Dental abscesses, which are collections of pus at the end of the teeth or in the gums, may develop.

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

Seeing a dentist

Visit your dentist regularly so early tooth decay can be treated as soon as possible and the prevention of further decay can begin. 

Tooth decay is much easier and cheaper to treat in its early stages. 

Dentists can usually identify tooth decay and further problems with a simple examination or X-ray.

Find your nearest dentist

It's also important to have regular dental check-ups.

Adults should have a check-up at least once every 2 years, and children under the age of 18 should have a check-up at least once a year.

Read more on:

• how to find an NHS dentist
• what to expect when you visit your dentist
• getting over a fear of the dentist

Treatments for tooth decay

Early-stage tooth decay

Early-stage tooth decay, which is before a hole (or cavity) has formed in the tooth, can be reversed by:

• reducing how much and how frequently you have sugary foods and drinks
• brushing your teeth at least twice a day with fluoride toothpaste

Your dentist may apply a fluoride gel or fluoride paste to the affected tooth.

Fluoride helps to protect teeth by strengthening the enamel, making teeth more resistant to the acids from plaque that can cause tooth decay

Treatments for holes in teeth

When there's a hole in the tooth, treatment may include:

• a filling or crown – this involves removing the dental decay and filling the hole or covering the tooth (read about what NHS fillings and crowns are made of)
• root canal treatment – this may be needed to remove tooth decay that's spread to the centre of the tooth where the blood and nerves are (the pulp)
• removing all or part of the tooth – this is usually advised when the tooth is badly damaged and cannot be restored; your dentist may be able to replace the tooth with a partial denture, bridge or implant

Cost of NHS treatment

NHS charges are set by the government and are standard for all NHS patients. Charges are assessed each year and usually change every April.

Some people do not have to pay for dental treatment, including children, pregnant women and new mothers.

Financial help may also be available to those on a low income.

Read more about:

• NHS dental charges
• getting help with dental charges

The cost of private dental treatment varies between practices, as there's no set charge.

If you choose to see a private dentist, make sure to agree the cost before having treatment.

Preventing tooth decay in adults

Although tooth decay is a common problem, it's often entirely preventable.

The best way to avoid tooth decay and keep your gums as healthy as possible is to:

• visit your dentist regularly – your dentist will decide how often they need to see you based on the condition of your mouth, teeth and gums
• cut down on sugary and starchy food and drinks, particularly between meals or within an hour of going to bed – some medicines can also contain sugar, so it's best to look for sugar-free alternatives where possible
• look after your teeth and gums – brush your teeth properly with a fluoride toothpaste twice a day, and use floss and an interdental brush at least once a day
• see your dentist or a GP if you have a persistently dry mouth – this may be caused by certain medicines, treatments or medical conditions

Read more about:

• how to cut down on sugar in your diet
• lifestyle tips for healthy teeth
• how sugar in our diet affects our health
• reading food labels

Protecting your child's teeth

Establishing good eating habits by limiting sugary snacks and drinks can help your child avoid tooth decay.

Regular visits to the dentist at an early age should also be encouraged.

It's important to teach your child how to clean their teeth properly and regularly. Your dentist can show you how to do this.

Younger children should use a children's toothpaste, but make sure to read the label about how to use it.

Children should still brush their teeth twice a day, especially before bedtime.

Read more about:

• how to look after your baby's teeth
• how to look after your children's teeth
• tips on giving your child sweets, fizzy drinks and using bottles

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.