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About tooth decay

Tooth decay, also referred to as cavity or dental caries, is an infectious disease. It develops slowly, gradually breaking down the hard tissues of teeth.

Tooth decay is the most common disease in the world. It affects the vast majority of the population, children and adults alike. According to World Health Organisation estimates, 60 to 90% of school children worldwide and close to 100% of adults have cavities. Tooth decay can occur very early; children can get cavities as soon as their first tooth appears.

Maintaining good oral hygiene and eating food that is low in sugar and acid helps prevent tooth decay.


Tooth decay is caused by sugars in food and bacteria activity in the mouth. These bacteria are concentrated in dental plaque, a whitish substance that also contains saliva and food particles. Dental plaque is deposited on the surface of teeth and is removed by brushing. When dental plaque stays on teeth, the bacteria it contains turn sugars in the food into acid. These acids attack teeth by forming a hole on the surface, which is the tooth decay. If left untreated, the hole widens and the cavity gets deeper.


A cavity first forms on the tooth’s outer layer, which is the enamel. It then breaks through into the dentine beneath the enamel.

If the cavity is left untreated, it ends up reaching the pulp, in the centre of the tooth where the nerves and blood vessels are located. The decay can destroy the pulp and leave a space inside the tooth. Bacteria can then penetrate this space and cause infection.

The development of cavities in 4 stages:

Stage 1

Cavity is limited to the enamel: no pain

Stage 2

Cavity reaches the dentine: teeth are sensitive to hot and cold

Stage 3

The cavity reaches the pulp: raging toothache

Stage 4

The dental pulp is infected: tooth abscess

Last update: August 28, 2023


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