What is tooth decay? Tooth decay is damage to your tooth’s surface, or enamel, from acids. If you don’t get treatment, this can progress to a small hole in your tooth, called a cavity, which can cause pain and an infection. In the later stages of tooth decay, you may even lose your tooth. What causes tooth decay? Tooth decay is caused by plaque acids gradually dissolving away your tooth. Plaque is a sticky film of bacteria over your teeth. When you eat or drink sugary things in particular, the bacteria in plaque produce acid, which can gradually break down the surface of your tooth and cause tooth decay. If a hole (cavity) develops in the enamel, the plaque and bacteria can reach the softer material underneath the enamel called dentine. What treatments are there for tooth decay? For very early tooth decay there are new techniques available which avoid the necessity for a dentist to have to remove the decay. If you have more advanced decay, your dentist can remove the decay and repair your tooth with a filling. If the nerve in the middle of your tooth is damaged, your dentist will perform root canal treatment to remove the nerve and repair your tooth with a filling or a crown. If you have a badly decayed tooth, your dentist might not be able to repair it and they’ll have to take the tooth out.