When you mention dental problems, most people probably think of having a cavity that needs to be filled by a dentist. While some think that this is just a problem for children, the fact is that tooth decay can affect anyone who doesn't look after their teeth properly. In fact, tooth decay is one of the most widespread health problems in the UK today. As mentioned at the start of this module, roughly a third of children start school with visible tooth decay. BDHF statistics also show that UK adults have an average of seven fillings each, and that 31 per cent have tooth decay.

The root cause of tooth decay is a substance called plaque, which begins life as the bacteria that live naturally in the mouth. These bacteria thrive on the food we eat and form a sticky film called plaque over the surface of the teeth and gums. This film of plaque is one of the main reasons we need to brush our teeth regularly. When we eat or drink foods that contain sugars or starches, the bacteria in the plaque produce acids, and these acids attack the enamel layer of the teeth.

Over time, this acid can destroy the enamel on the surface of the tooth and a cavity will form as a result. Left untreated, dental cavities (or caries as they are also known) can destroy a tooth. The only way to stop this damage is to have the cavity filled by a dentist. In older people, tooth decay can occur in teeth that have already been filled. Over time, fillings may weaken and fracture or leak around the edges. Bacteria can accumulate in these tiny cracks, producing acids that lead to further decay.