Cavities (tooth decay): symptoms, treatment and prevention

A cavity, also called a dental cavity or hole in a tooth, is damage that has broken through the surface of a tooth because of tooth decay. The NHS explains that decay happens when bacteria create a sticky layer called plaque over your teeth, which damages the surface of your teeth over time. It is often caused by having too much sugary food and drink and not cleaning your teeth and gums regularly.

Tooth decay can be stopped and reversed in its earliest stage, before a hole forms. The NHS says a dentist can prescribe fluoride treatments like mouthwash or varnish to reverse early tooth decay. Once there is a cavity, the tooth cannot repair itself and usually needs a filling.

The NHS says tooth decay may not cause any symptoms at first, which is why regular check-ups matter. If it gets worse, it can lead to a hole forming in the tooth. If you have a hole in your tooth you may have the problems below. Sometimes the tooth or gum can become infected, leading to a painful build-up of pus (a dental abscess).

• Toothache (tooth pain).

• Sharp pain in your tooth when eating or drinking hot, cold or sweet things (sensitive teeth).

• White, brown or black spots on your tooth.

• Painful, swollen gums, or gums that bleed when you brush.

The NHS says to see a dentist if you have problems with your teeth like toothache or a sharp pain in your tooth when eating or drinking, or if your gums are painful, swollen or bleed when you brush. You should have regular check-ups even if you do not have problems: the NHS says to see a dentist if you have not had a check-up for 2 years (or 1 year if you are under 18).

A dental abscess needs urgent treatment by a dentist and will not go away on its own. The signs listed by the NHS are intense toothache or pain in your gums, redness inside or outside the mouth on the face or jaw, a bad taste in your mouth, difficulty opening your mouth and chewing, a swollen face or jaw, swollen glands in your neck, and a high temperature.

The NHS says treatment for tooth decay depends on how severe it is. For early decay a dentist can prescribe fluoride treatments. If you have a cavity, you will probably need a filling. If decay has reached the soft tissue (pulp) in the middle of your tooth, you may need root canal treatment, and sometimes the affected tooth may need to be removed (extraction).

Root canal treatment removes an infection from inside the tooth, which is then cleaned and filled. The NHS says the infected pulp is removed, any abscess is drained, the inside of the tooth is cleaned and shaped, and a filling put in, usually under local anaesthetic, over 2 or more appointments. A crown may be needed if the tooth was badly infected. Without root canal treatment, an infected tooth may need to be taken out.

The NHS says tooth decay is common in children, so it is important to help them look after their teeth and gums from an early age. NHS dental care for children is free. It advises taking your child to the dentist when their first milk teeth appear, or before they are 12 months old, so they become familiar with the environment and the dentist can advise on preventing decay.

The NHS says parents or carers should brush a baby's teeth as soon as the first milk tooth breaks through (usually at around 6 months, but it can be earlier or later), twice daily for about 2 minutes with fluoride toothpaste, last thing at night and on one other occasion. Children need to be helped or supervised brushing until they are at least 7.

The NHS says fissure sealants can be done once permanent back teeth start to come through (usually at about 6 or 7) and again when the rest of the teeth come through between 11 and 14 years. The chewing surfaces of back teeth are covered with a thin plastic coating to keep germs and food particles out of the grooves. It protects against decay and lasts up to 4 years.

Fluoride varnish can be applied to baby teeth and adult teeth. It is painted onto the surface of the tooth, usually every 6 months, to strengthen enamel and make it more resistant to decay. From the age of 3, children should be offered fluoride varnish at least twice a year, and younger children may be offered it if the dentist thinks they need it.

The NHS says tooth decay is often caused by having too much sugary food and drink and not cleaning teeth and gums regularly. Plaque, a film of bacteria that coats the teeth, contributes to gum disease and tooth decay. The NHS advice on prevention also lists not smoking and not regularly drinking more than 14 units of alcohol a week.

The NHS advice on brushing says to use a toothpaste with the right concentration of fluoride, and to avoid rinsing your mouth with water straight after brushing, because rinsing washes away the concentrated fluoride and reduces its protective effect.

The NHS says the following simple steps help keep teeth and gums healthy and prevent tooth decay.

• Brush your teeth at least twice a day for about 2 minutes with fluoride toothpaste, last thing at night and on one other occasion. Spit after brushing and do not rinse.

• Adults should use a toothpaste containing at least 1,350ppm fluoride. Electric and manual toothbrushes are both fine if you clean every surface of every tooth.

• Clean between your teeth every day using floss or interdental brushes.

• Cut down on sugary food and drink, and use sugar-free medicines.

• Have regular dental check-ups; your dentist will advise how often you need them.

• Do not smoke, and do not regularly drink more than 14 units of alcohol a week.

The NHS says NHS dental treatment is free for people who are pregnant or have had a baby in the past 12 months, as well as for children under 18 (or under 19 and in full-time education) and for people on some benefits such as Income Support. If you do not qualify for free care, you will usually have to pay for treatment.

You can have dental treatment from an NHS or a private dentist. Most people need to pay for NHS dental treatment. The NHS says root canal treatment is classed as a band 2 treatment under NHS dental charges, and some people are entitled to free NHS dental treatment or help with dental costs.

Whichever route you take, ask what the treatment will involve, what it will cost, how long it should last, and how to look after the tooth. If you need urgent care out of hours and do not have a dentist, the NHS says to call 111 or use 111 online to find where to get help; you may have to pay for the appointment.