Understanding Tooth Decay
Tooth decay is one of the most common health problems in the UK. Find out what causes it, how to spot it early and how to stop it.
What is tooth decay?
Tooth decay happens when acid damages the hard outer layer of your tooth (the enamel). Over time, this can make a hole in the tooth.
You may also hear it called dental caries or cavities.
It is one of the most common health problems in the UK. Around 1 in 3 adults with natural teeth (31%) had obvious tooth decay in the Adult Dental Health Survey 2009 (England, Wales and Northern Ireland).
It is also the main reason children go into hospital for a dental procedure.
The good news is that you can almost always prevent tooth decay. If it is found early, it can often be stopped or even reversed without a filling.
What causes tooth decay?
Millions of germs (bacteria) live in your mouth. Some of them feed on the sugar in what you eat and drink. As they feed, they make acid. This acid attacks and softens your enamel.
Your spit (saliva) helps wash the acid away. It also repairs early damage. But if acid attacks happen too often, the enamel cannot recover fast enough. Then decay starts.
These things raise your risk:
- Having sugary or acidic food and drinks often through the day
- Not brushing or flossing well, so plaque builds up on your teeth
- A dry mouth. Saliva protects your teeth, so less saliva means more risk.
- Roots that are showing. The root is softer than enamel and decays more easily.
- Some medicines that make you produce less saliva
- Deep grooves in your back teeth, where plaque is harder to clean away
Signs to look out for
Early tooth decay often causes no pain and no clear signs. This is why regular check-ups matter. Your dental team can spot decay before you feel it.
As decay gets worse, you may notice:
- A white, chalky spot on a tooth. This is the first sign you can see.
- A brown or black stain, or a hole you can see in the tooth
- Sensitivity to sweet foods, or to hot or cold drinks
- A toothache, mostly when you eat or drink
- A constant, throbbing ache. This may mean the decay has reached the nerve.
If you notice any of these signs, book an appointment soon. The earlier decay is found, the simpler the treatment.
How is tooth decay treated?
Treatment depends on how far the decay has spread:
- Early decay (white spots). The enamel has not fully broken down yet. Your dental team may suggest fluoride treatment. They may give you advice on food and drink, and on brushing better. No drilling is needed.
- A small or medium hole (cavity). Your dental team will remove the decay. Then they will place a filling to bring back the shape and use of the tooth.
- Decay that has reached the nerve. You may need root canal treatment to save the tooth. This cleans out the infected nerve from inside the tooth.
- Very bad decay. If the tooth cannot be saved, taking it out (extraction) may be the only option.
Your dentist will talk with you about the best option for you. This depends on how much decay there is and on your own situation.
What you can do at home
The best tools against tooth decay are simple and free:
- Brush twice a day with a fluoride toothpaste. Brush last thing at night and at one other time.
- Adults should use a pea-sized amount of toothpaste.
- Spit out, do not rinse, after brushing. Rinsing washes away the fluoride that protects your teeth.
- Clean between your teeth every day with floss or small brushes (interdental brushes). A toothbrush cannot reach between your teeth.
- Cut down on sugar. How often you have sugar matters, not just how much. Try to keep sugary food and drinks to mealtimes.
- Choose water or plain milk as your main drinks. Avoid sugary drinks, fruit juice and fizzy drinks between meals.
- Chew sugar-free gum after meals. It makes more saliva, which helps cancel out acid.
When to see your dental team
Book an appointment soon if you have:
- Toothache that lasts more than a day or two
- Sensitivity that does not go away
- A hole, chip or dark stain you can see on a tooth
- Pain when you bite or chew
- Swelling in your gum or face near a tooth
Do not wait for pain before you see your dental team. Go to regular check-ups, as often as your dental team suggests. This is the best way to find decay before it causes problems.
Preventing tooth decay
Preventing decay is always better, and cheaper, than treating it. The key steps are:
- Go to regular dental check-ups, as often as your dental team advises.
- Use a fluoride toothpaste. Fluoride makes enamel stronger and reverses very early decay.
- Ask your dental team about fissure sealants for children. This is a protective coating for the deep grooves in back teeth.
- If you are at high risk, think about a stronger, prescription fluoride toothpaste. Your dental team can arrange this.
- Talk openly with your dental team about what you eat and drink. They can give you advice that fits you.
This leaflet is for general information only and does not replace professional dental advice. Your dental team will discuss your individual circumstances and any risks and treatment specific to you. Treatment outcomes vary between patients depending on individual circumstances.
Sources
- Delivering better oral health: an evidence-based toolkit for prevention, 4th edition. Department of Health and Social Care and NHS England, 2021, updated September 2025.
- Oral health promotion: general dental practice (NG30). National Institute for Health and Care Excellence (NICE), 2015.
- Prevention and Management of Dental Caries in Children, 3rd edition. Scottish Dental Clinical Effectiveness Programme (SDCEP), 2025.
- Tooth decay. NHS website (nhs.uk), reviewed August 2025.
- Adult Dental Health Survey 2009: summary report. NHS Information Centre for Health and Social Care, 2011.
Links checked 18 October 2026.
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