Root canal therapy is necessary when the pulpal tissue (nerve) in the tooth is no longer vital. The most common cause of a “dead” tooth is when a dental cavity reaches the pulp and the bad bacteria cause an infection. This can lead to a toothache and even a dental abscess. The cavity is cleaned out, the nerve of the tooth is removed, and the empty roots are filled with a biologically compatible material. Some teeth may also need root canal therapy after a dental trauma has rendered the pulpal tissue non vital or when proper restoration of a dental trauma would encroach on the nerve space. Most teeth that have had root canal therapy done benefit from having a crown placed after everything has healed.