Also known conventionally as a ‘root canal’, this treatment may be required for a number of reasons. Most often a root canal is needed when a cavity goes deep enough into the tooth that it goes into the nerve of the tooth, producing the sensation of pain; It can also occur from a stressful procedure done to the tooth, such as a filling that is very deep and close to the nerve, or a crown or bridge treatment, or from trauma.  Root canals are meant to be painless, and sometimes antibiotics will be prescribed beforehand to eliminate some pain and infection, however, a root canal is required to remove the source of infection.  A small hole is drilled in the top of the tooth and the nerve tissue and all the bacteria and infection is removed, and an inert filling material is placed in the tooth.  A crown is recommended after a root canal as it causes the tooth to be brittle, and the tooth will often break afterwards if a crown is not placed.