Your mouth is full of bacteria, which combine with small food particles and saliva to form a sticky film known as plaque, which builds up on your teeth.

When you consume food and drink high in carbohydrates (sugary or starchy), the bacteria in plaque turn the carbohydrates into energy they need, producing acid at the same time.

Over time, the acid in plaque begins to break down the surface of your tooth.

The plaque will first start to erode the enamel. Over time, a small hole known as a cavity can develop on the surface. This will cause toothache.

Once cavities have formed in the enamel, the plaque and bacteria can reach the dentine. As the dentine is softer than the enamel, the process of tooth decay speeds up.

Without treatment, plaque and bacteria will enter the pulp. At this stage, your nerves will be exposed to bacteria, making your tooth very painful. The bacteria can also infect tissue within the pulp, causing a dental abscess.

Tooth decay typically occurs in teeth at the back of your mouth, known as molars and premolars. These are large flat teeth used to chew food. Due to their size and shape, it is easy for particles of food to get stuck on and in between these teeth. They are also harder to clean properly.

It is more common for a front tooth to be affected by tooth decay when it is touching another tooth alongside it.