Definition
Caries affects the hard tissues of the tooth (ie the enamel and dentine) and is caused by the action of bacteria on fermentable carbohydrates (sugar) in the patient's diet.

Incidence
This may occur at any age.

Presentation
In the young patient, primary teeth may be affected, with first molars being at risk when they erupt at age 6 to 7 years. Initially the chewing (occlusal) surfaces may be affected, but later the decay may occur on the front and back surfaces of the teeth. Early decay in these areas may often only be diagnosed using small "bitewing" radiographs.

Figure 1. Dental decay starting to affect front of teeth.

Figure 2. Severe dental decay.

Causes
Dental decay occurs when sugars are metabolised by the bacteria which are present in everyone's mouth. It therefore follows that sweet foods and drinks, sugar in drinks (such as tea) may lead to decay. The more frequently these sweet foods are ingested, the more the chance of decay. It also follows that patients who do not brush their teeth adequately (who have collections of debris, or plaque on their teeth) will allow the bacteria to metabolise the sugars in the debris on their teeth, and this will lead to decay. Some people are more susceptible to this than others.

Symptoms/Signs
The affected teeth will eventually cavitate, and the patient will initially experience sharp bouts of pain, especially on hot and cold substances. If the decay is not removed at this stage, it may progress to involve the pulp (nerve) of the tooth. At this stage, an extraction or root canal treatment may be the only treatment possible.

Complications of Disorder
Untreated the dental decay my lead to a dental abscess.

Tests
Radiographs are taken of the tooth.

Treatment
Early decay may be prevented from progressing. At an early stage, decay may be prevented from progressing if the patient ceases to consume sweet foods and drinks, commences a diligent toothbrushing routine, and uses a fluoride containing toothpaste.

Later, a filling may be required. Later still, root canal treatment (involving removal of the nerve and filling the nerve space) or extraction of the tooth may be necessary.

Outcome/Prognosis
Properly treated dental decay can be removed and the tooth restored by a filling. The ideal outcome is to prevent the decay from happening and this is related to a sugar free diet.