Root canal therapy (endodontics) is generally the only option to save a tooth that has severe decay that exposes the nerve (pulp) or has become infected. The diseased pulp tissue is removed using small instruments that will fit into the tiny canals of the root of the tooth The cleansed and disinfected canals are permanently sealed with a rubber filling called gutta percha Without the nerve, the tooth can become dry, brittle and easy to break. It is normally necessary to install a crown over the tooth to properly restore it and ensure its strength.