When a cavity reaches deep into a tooth and starts to affect the pulp of the tooth, a root canal may be needed. A root canal is done to save a tooth that would otherwise further decay and weaken structurally.
The procedure of a root canal involves removing the pulp and nerve of a tooth and replacing it with a rubber (gutta percha) material. After a root canal is completed, the tooth may need a crown to help strengthen the remaining tooth structure from everyday biting forces.