A post and core crown is a type of dental restoration required where there is an inadequate amount of sound tooth tissue remaining to retain a conventional crown. A post is cemented into a prepared root canal, which retains a core restoration, which retains the final crown. How do you post and core build up? We'll use a small instrument called a dental file to shape the top of the root canal, select a post, and then cement or bond it in place. After the post is in place, we fill the tooth with the new core material. Once it has hardened, the core material is shaped and prepared to receive a crown.