Root canal therapy is required when the dental nerve is damaged. In a healthy tooth, blood vessel, nerve and lymphatic systems are all present inside a hollow tube inside the tooth. When a tooth is diseased, all the dead tissue must be removed, cleaned and sealed. The success of a root canal treatment depends on the perfect hermetic seal of the tooth on both ends.

The success rate of modern root canal technique is very high. However, due to variations in shape of teeth, sometimes failures can occur; although at very low percentage.