One of the most common causes of tooth decay is the build up of dental plaque on the teeth. Dental decay often develops when acids produced by bacteria present in the plaque start to erode the surface of the tooth.

Parts of a tooth

• The inner pulp forms the soft centre of the tooth and contains the nerves and blood vessels of the tooth
• A bone-like material called dentine surrounds the pulp. This is softer than the outer covering of the tooth
• The hard outer cover of the tooth is called enamel

Development of tooth decay

Tooth decay or caries is usually caused by the accumulation of food particles around the sides and in-between the teeth. Not cleaning the teeth adequately after eating and eating sugary foods which tend to form a film across the teeth often leads to decay as these food particles usually give rise to the growth of bacteria.

The bacterial colonization of the teeth usually creates a thin, sticky, colorless film over the teeth - the dental plaque. As soon as food is eaten, its sugar content is utilized by bacteria present in the dental plaque to form acid and this acid slowly dissolves the surface of the tooth or the enamel. This erosion causes the loss of minerals such as calcium and eventually the whole of the enamel may be destroyed, leading to deformed and damaged teeth with cavities.

Typically, the teeth at the back of the mouth are affected first as these are the larger teeth with a greater, flatter surface area. Being located at the back of the mouth, these teeth are also harder to reach and clean so are more likely to harbour bacteria. Front teeth tend to be affected only when the neighbouring teeth are already affected.

Risk factors for tooth decay

Some factors raise the risk of tooth decay. These include:

• Diets high in sugar and carbohydrates increase the risk of tooth decay and snacking on these types of food between main meals should be avoided.
• Maintaining good oral hygiene by brushing the teeth twice daily as well as flossing can help keep tooth decay at bay. Inadequate oral hygiene along with an unhealthy diet increases the likelihood of tooth decay.
• People who suffer from eating disorders such as bulimia tend to eat excessively and then force themselves to vomit. Excessive and repeated vomiting leads to exposure of the teeth to the acids present in the stomach and increase the risk of decay.
• Smokers and people who use chewing tobacco are at a greater risk of tooth decay.
• Saliva protects the teeth from tooth decay, so people with a condition called "dry mouth" have a greater risk of tooth decay. Dry mouth can result from using certain medications such as tricyclic antidepressants, anticholinergic agents, anticonvulsants, antipsychotics, antihistaminics and antihypertensive medications.