Tooth decay

The causes of tooth decay

Tooth decay occurs when the outer layers of a tooth are softened, creating a hole in the tooth. These holes are called cavities. The softening is caused by plaque acid dissolving the enamel and dentine of your teeth.


Enamel is the hard outer layer of the tooth. It is the hardest part of the human body and works to protect your teeth. However, it can still be damaged by plaque acid. There are no nerves or blood vessels in the enamel so it does not hurt.

Dentine is the layer underneath the enamel which makes up most of the tooth. It surrounds the pulp, which is the part of the tooth that contains the nerves and blood vessels. Unlike enamel, dentine is sensitive to pain.

Plaque is a film on the surface of your teeth that contains lots of different kinds of bacteria. Although brushing regularly helps to get rid of plaque, it is constantly forming on your teeth. The bacteria in plaque reacts with sugar in the things you eat and drink, creating acid. This acid can dissolve the enamel for up to an hour after eating or drinking, until the salt in your saliva helps the enamel to harden again. The biting surfaces of the teeth and the areas between the teeth are most susceptible to decay, as food can easily get trapped in these areas.

The signs of tooth decay

The early stages of tooth decay are not visible on the outside of your teeth, but may be picked up using an x-ray. It is much easier to treat smaller cavities than more advanced decay, which is why we like to x-ray the teeth of new patients, and take regular x-rays of existing clients’ teeth.

If the decay has become more advanced and reached the dentine of the tooth, you may find that your tooth becomes more sensitive, particularly to sweet, acidic, or hot foods.

Man receiving a dental check up

If the cavity is left untreated and the decay gets closer to the pulp, the tooth will become more and more painful, eventually leading to permanent toothache. If the decay is allowed to reach the pulp it is very likely to cause an abscess and the tooth itself may die and need to be removed.

Treating cavities

If the cavity is relatively minor, your dentist will treat it by removing all of the decay and filling the cavity. If we manage to detect the decay in its very early stages, your dentist may be able to treat it by applying a fluoride varnish to the tooth, rather than filling it.

If the cavity has been left untreated for a long time and the decay has reached the pulp of the tooth, root canal treatment may be necessary.

Preventing tooth decay

The best way to prevent tooth decay and avoid cavities is to brush your teeth properly twice a day, using a good fluoride toothpaste. It is important to brush every exposed surface of each tooth. Dental floss or tape can be used to remove food and plaque from the areas between your teeth.

Fissure sealant can also be applied to healthy teeth, to prevent food and germs from entering the small pits and fissures that appear in the surface of a tooth. Regular check-ups can help to detect and treat signs of tooth decay early on.

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