A root canal is a procedure that extracts decayed pulp from the central part of the tooth, reshapes the canal and replaces it with strengthening filler.

A cavity is the result of superficial decay of the enamel of the tooth. Left long enough, this decay can burrow into the deeper reaches of the tooth, causing extensive damage to tooth structure. When the damage goes beyond what can be treated with a filling, dentists can perform a root canal (or endodontics), preserving the tooth and retaining its original integrity; thereby, saving a tooth that in the past would have to have been pulled.