Almost all endodontically treated teeth need to be reinforced. Patients occasionally complain that root canals do not work because the tooth can break and has to be removed. It is unfortunate for both patient and dentist to have endodontics performed and a crown placed without reinforcement, only to have the tooth fractured. The criteria for a post must-emphasize the factors that provide support to the entire tooth and provide retention for the coronal restoration. The combined post and care should minimize the loss of tooth structure and reduce unnecessary stress. Various guidelines are suggested for the proper length of the post. Many different types of prefabricated posts are available.