Many times a tooth will develop an infection in the tooth that can be caused from many reasons including decay, a crack, or trauma (these are the most common). Often the only way to save the tooth at this time is with a root canal, the only other option being to extract the tooth. A root canal will remove the dying nerve (that is causing the infection), and fill the nerve canals with a material called gutta percha. Once the nerve is removed, the tooth will need a build-up to fill in the missing structure. A post may be needed if it was necessary to remove a lot of the tooth structure. This is followed-up with a crown to give stability and function.