A root canal is a dental surgery which is done to treat infection at the centre of the tooth or the root canal system. The infection is caused due to bacteria which live in the mouth and invade the tooth. Tooth decay and improper tooth fillings are also reasons for infections in the root canal system.
Damage to the teeth can also be caused due to trauma which might internally damage the pulp of the teeth. A root canal treatment is done when the pulp of the teeth get infected by bacteria, multiplies and spreads.