Posts and Cast Posts
A post is small metal shaft that is implanted into the root of the tooth. A post is placed inside the root of a tooth to help stabilise the tooth and make it a more secure structure, this is generally done so that a crown or other kind of prosthetic can be placed on the structure. This treatment can only be done to a tooth that has had root canal treatment.
A cast post is similar to a post however the small metal shaft is not implanted into the root of the tooth. The post is instead made attached to a crown that is to be placed on the tooth and when the crown is cemented to the tooth the metal shaft then sits in the root of the tooth. Once again this can only be done when a tooth has been root treated.
Your dentist will let you know where a post or cast post is necessary.