When a large proportion of tooth tissue is missing (> 40%) either due to long amounts of caries, or due to fracture, or due to previous root canal therapy, this tooth usually needs to be restored with a post placement in the root to strengthen it. In the prefabricated posts the post can be made of carbon fiber or fiberglass, or in the cast posts of metal or gold. The post type selection, which will be placed, is made by the dentist based on the post properties that concern: biocompatibility, physicochemical properties, handling characteristics, aesthetic and financial costs.