When is a prefabricated post and core installed?

After root canal : A pre-fabricated post and core (or custom post and core) are done after a root canal is completed on a tooth, but before a crown is fabricated! The post and core strengthens the tooth and helps evenly distribute the forces of chewing.

Before the crown: When the tooth is prepared to receive the crown, in many instances there is not enough tooth structure remaining to retain the crown. A prefabricated post and core can be used to replace the missing tooth structure. Of course a root canal procedure must first be done in the tooth.