BSIP / SCIENCE PHOTO LIBRARY BSIP / SCIENCE PHOTO LIBRARY
Tooth decay. Coloured X-ray of teeth showing an area of tooth decay (black, upper left). Healthy teeth are yellow and the gum is red. Tooth decay (dental caries) is usually caused by a build-up of plaque, a mixture of food remnants, saliva and bacteria. Bacteria produce acids as they feed on the food, which weakens the enamel of the teeth. This allows the bacteria into the inner parts of the tooth, exposing the pulp at its centre. If this becomes infected, the tooth dies. Tooth decay can be prevented by regular brushing, which removes much of the plaque, and by visiting a dentist, who can remove plaque from hard to reach areas.
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