When there is not enough tooth structure remaining after trauma, decay or a root canal procedure, then a post and crown will be utilized to restore the tooth to full form and function. A crown buildup is either composed of a bonded composite material or possibly an amalgam material. If a crown is placed on an unstable tooth foundation you will have a higher risk of having that crown fail. When the tooth has lost significant structure then a buildup is necessary in order to provide proper support of the new crown and to bring the tooth back to full function.