Tooth decay (caries) is very common, and affects people of all ages. Look at the model to see a hole (or cavity) forming in a tooth, and watch how an abscess forms at the root tip when the hole gets very large. To find out about the parts of a tooth and what they are called, take a look at the dissected tooth in the lifetime of teeth section of the site.

How does tooth decay happen?

Tooth decay can occur if plaque is left on teeth. It is the tiny bacteria which live in plaque that cause it to happen. When tooth decay first starts, the bacteria make acids (which they let out into the plaque), and which soften the tooth's surface. The acids actually dissolve away the minerals in the tooth's outer surface (or enamel), and this process is known as demineralisation.

Bacteria need to feed on the sugars in food and drink that we consume to make this happen (sugars such as sucrose, glucose and fructose). Once all the sugar has been used up after eating or drinking something sweet, the acid in plaque gradually disappears and the tooth has a chance to repair itself (called remineralisation). The minerals in saliva help this to happen, and so does the fluoride in toothpaste. If plaque (containing the bacteria) is not removed regularly, or if sugar is eaten too often, then plaque bacteria can keep producing more and more acid, and the tooth doesn't get a chance to repair itself properly. Eventually a small hole (or cavity) appears, like the one shown in the model.

What can happen next?

As more and more acids are produced, the hole gets bigger and bigger, and goes deeper towards the living part of the tooth (called the pulp). This makes the tooth more and more sensitive, especially to hot and cold things. Eventually, when the hole gets large enough, the pulp becomes damaged and can die to leave an empty space inside the tooth where the pulp used to be. Bacteria from the mouth can get inside the tooth and cause an infection (known as an abscess) at the very end of the root (or root tip).

Did you know?

  • Tooth-brushing with a fluoride toothpaste helps to remove plaque, and prevent this from happening.
  • Also, cutting down on sugary foods and drinks helps protect teeth, especially if you only have them at mealtimes.
  • Dentists can repair holes in teeth with fillings, and help prevent them getting too big and painful.
  • Chewing a sugarfree gum like Orbit after meals and snacks helps prevent tooth decay.
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