Tooth decay — also called dental caries or cavities — happens when the outer layer of your tooth (the enamel) is damaged by acid. Over time, this can create a hole in the tooth.
It is one of the most common conditions in the UK. Around 1 in 3 adults have some degree of tooth decay, and it is the leading reason children are admitted to hospital for a dental procedure.
The good news is that tooth decay is almost entirely preventable, and when caught early, it can often be stopped or even reversed without a filling.
What causes tooth decay?
Your mouth is home to millions of bacteria. Some of these bacteria feed on sugars from the food and drinks you consume, and produce acid as a by-product. This acid attacks and softens the enamel on your teeth.
Your saliva helps to wash away this acid and repair early damage — but if acid attacks happen too often, the enamel cannot recover fast enough, and decay begins.
The main factors that increase your risk include:
Eating or drinking sugary or acidic foods and drinks frequently throughout the day
Poor brushing and flossing habits — allowing plaque to build up on teeth
A dry mouth — saliva protects teeth, so less saliva means more risk
Exposed root surfaces — the root is softer than enamel and decays more easily
Certain medications that reduce saliva flow
Deep grooves in back teeth where plaque is harder to clean away
Signs and symptoms to look out for
In its earliest stages, tooth decay often causes no pain or obvious signs. This is why regular check-ups are so important — your dentist can spot decay before you feel it.
As decay progresses, you may notice:
A white, chalky spot on a tooth — this is the first visible sign
A brown or black stain or visible hole in the tooth
Sensitivity to sweet foods, hot or cold drinks
A toothache — especially when eating or drinking
A constant, throbbing ache — this may mean the decay has reached the nerve
If you notice any of these signs, please book an appointment promptly. The earlier decay is caught, the simpler the treatment.
How is tooth decay treated?
Treatment depends on how far the decay has progressed:
Early-stage decay (white spot lesions) — at this stage the enamel has not yet broken down completely. Your dentist may recommend fluoride treatment, dietary advice, and improved brushing. No drilling is needed.
A small to moderate cavity — your dentist will remove the decayed tooth tissue and place a filling to restore the shape and function of the tooth.
Decay that has reached the nerve — root canal treatment may be needed to save the tooth. This cleans out the infected nerve tissue from inside the tooth.
Severe decay — if the tooth cannot be saved, removal (extraction) may be the only option.
Your dentist will discuss the most appropriate option for you based on the extent of the decay and your individual circumstances.
What you can do at home
The most powerful tools against tooth decay are simple and free:
Brush twice a day with a fluoride toothpaste — last thing at night and at one other time. Use a pea-sized amount for adults.
Do not rinse after brushing — spitting out excess toothpaste is enough. Rinsing washes away the fluoride that protects your teeth.
Clean between your teeth daily using floss or interdental brushes. A toothbrush cannot reach between the teeth.
Cut down on sugar — it is not just how much sugar you eat, but how often. Try to limit sugary food and drinks to mealtimes.
Choose water or plain milk as your main drinks. Avoid sugary drinks, fruit juices, and fizzy drinks between meals.
Chew sugar-free gum after meals — it stimulates saliva, which helps to neutralise acid.
When to see your dentist
You should book an appointment soon if you experience:
Toothache that lasts more than a day or two
Sensitivity that does not go away
A visible hole, chip, or dark stain on a tooth
Pain when biting or chewing
Swelling in your gum or face near a tooth
Do not wait for pain before seeing your dentist. Attending regular check-ups (at the interval your dentist recommends) is the best way to catch decay before it causes problems.
Preventing tooth decay
Prevention is always better — and cheaper — than treatment. The key steps are:
Attend regular dental check-ups at the frequency your dentist advises
Use a fluoride toothpaste — fluoride strengthens enamel and reverses very early decay
Ask your dentist about fissure sealants for children — a protective coating for the deep grooves in back teeth
Consider a prescription-strength fluoride toothpaste if you are at high risk — your dentist can prescribe this
Discuss your diet honestly with your dentist — they can give you personalised advice
This leaflet is for general information only and does not replace professional dental advice. Your dentist will discuss your individual circumstances and any risks and treatment specific to you. Treatment outcomes vary between patients depending on individual circumstances.
References
Aligned with guidance from: NICE, SDCEP, DBOH, FGDP(UK).