Dental Caries

Progressive decay of one or more teeth, causing cavities to form

  • More common under the age of 25
  • Poor oral hygiene and a diet high in sugar are risk factors
  • Gender and genetics are not significant factors

Gradual, progressive decay of a tooth is known as dental caries. This condition usually starts as a small cavity in the enamel (the hard, protective outer covering of a tooth). If left untreated, the decay eventually penetrates the outer layer of enamel and attacks the dentine, the softer material that makes up the bulk of a tooth. As the tooth decay progresses, the pulp (the living core of the tooth that contains the nerves and blood vessels) may be affected (see Pulpitis). If the pulp is exposed to decay and becomes infected, it may die.

Most people develop dental caries at some time in their lives. In younger age groups, tooth decay most often occurs on the chewing surfaces of the teeth and on the smooth surfaces between adjacent teeth. In older people, tooth decay is more common at the gum margins where the teeth meet the gums.

In developed countries, the number of teeth lost as a result of dental caries has fallen considerably in recent years, particularly among children. This fall is partly due to the addition of fluoride to drinking water in some areas and to the widespread use of fluoride toothpaste, both of which help to harden the teeth, making them more resistant to decay.

What are the causes?

Tooth decay is usually caused by a build-up of plaque (a deposit of food particles, saliva, and bacteria) on the surface of the teeth. The bacteria in plaque break down the sugar in food to produce an acid that erodes the tooth enamel. If sugary foods are eaten often and the teeth are not cleaned thoroughly soon afterwards, a cavity is eventually likely to form.

The condition is especially common in children, adolescents, and young adults because they are more likely to have a diet high in sugar and fail to clean their teeth regularly. Babies or young children who drink milk or juice from a bottle frequently throughout the day or who sleep with a bottle of milk or juice in their mouth may also develop severe caries.

What are the symptoms?

There may be no signs of dental caries in the early stages, but the symptoms develop gradually as the decay progresses and may include:

  • Toothache, which may be constant or sharp and stabbing and triggered by hot, cold, or sweet foods or drinks.

  • Persistent, throbbing pain in the jaw and occasionally in the ear and face, which may be worse when chewing.

  • Bad breath.

Pain in a tooth can take several forms. It may be persistent, recurrent, or set off by extremes of hot or cold or pressure on the tooth. You should see your dentist as soon as possible after the pain first appears and make an immediate appointment if the pain ends abruptly because this may indicate that the nerves and blood vessels have died. Delaying a visit to your dentist may result in the spread of infection, and an abscess may eventually form (see Dental abscess).

What might be done?

Your dentist will examine your teeth with a probe and a mirror to look for areas of tooth decay. An X-ray may also be taken to look for decay that may be developing beneath the surface of the teeth (see Dental checkup).

If you have superficial dental caries restricted to the surface of the enamel, your dentist may only apply fluoride to the affected area and advise you to be more careful about oral hygiene.

If tooth decay has penetrated further into the enamel or if it has affected the dentine, your dentist will probably need to fill the affected tooth (see Tooth filling). An injection of a local anaesthetic is often used to numb the tooth and nearby gum to prevent you from feeling pain. When the area is numb, the decayed parts of the tooth are drilled out, and the cavity is cleaned and filled to prevent further decay. If you have pulpitis and the pulp cannot be saved, you may need to have root canal treatment.

Can it be prevented?

Your teeth and gums should be brushed and flossed regularly to keep them clean (see Caring for your teeth and gums). You can also help to prevent dental caries from developing by avoiding sweet foods and drinks.

Test: Dental Checkup

Self-help: Caring for your Teeth and Gums

Treatment: Tooth Filling

Treatment: Root Canal Treatment

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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