A tooth has several outer layers to protect the most inner part of a tooth that contains the nerves and blood vessels (known as the pulp). If the pulp becomes irreversibly damaged or infected through decay or injury, root canal treatment (or endodontic treatment) is required to save the tooth.
Root canal treatment is simply the removal of the damaged or infected pulp from inside the tooth and roots and subsequently filling this space with a root filling material.
Root canal treatment can be completed in one or multiple visits and can be carried out painlessly. The first part of treatment involves removing the infected tissue from the roots, then shaping the canals and flushing them out with antibacterial agents. Finally, the clean roots are filled with a rubbery antibacterial material. The tooth may then require a post and/or a core build up before it is protected with a crown or onlay. These restorations are used to protect the treated teeth as they become more susceptible to fracture following root canal treatment.
The only alternative option to a root canal treatment would be removing the irreversibly damaged pulp by extracting the tooth.
Re-root canal treatment may required should the first attempt have failed, or planned treatment is required on a poor quality root filling. This can occasionally be completed by your dentist, however in more complex circumstances this may be referred to an external endodontist. As a last resort, surgery may be required where the end of the root is polished and cleaned directly.