Endodontics is the dental specialty that deals with the nerves of the teeth. When a tooth becomes infected it is usually related to the nerves in the root of the tooth. The infected nerves need to be removed. If left untreated an infection can turn into an abscess, which is a much more serious problem that includes bone loss in the jaw.
When root canal therapy is indicated, the area around the tooth is numbed with a local anesthetic. The dentist will then access the nerve of the tooth. They will be able to remove infected tissue and clean the canal. After the infection has been removed, the space is filled with a sealant called gutta percha. It is highly recommended that a tooth that has undergone a root canal is fitted with a crown. This will improve the strength of the tooth and will also make it much more likely that the root canal is successful long term.
This procedure will relieve you from pain caused by the infection. Root canals are beneficial in that they resolve infection and allow you to keep your natural tooth.