Reinforcing and restoration of badly broken root canal treated teeth can be done with post core system. Due to the availability of prefabricated posts of various designs and surface configuration, the fabrication time and costs has been reduced. For a successful post core system, the clinician should keep in mind regarding proper obturation, post space, post length, post diameter, ferrule design and should preserve the root dentin as much as possible It has been the purpose of this Book to provide a rationale for the restoration of endodontically treated teeth. The dowel and core should possess a positive seat to prevent a wedge-like action of the post. The transverse and vertical shape of the prepared root canal should follow the contour of the exterior root surface. With such a wide variety of materials and post designs available for the restoration of endodontically treated teeth, the clinician should be selective in choosing the post system that best fits the individual needsof each tooth. The criteria and factors presented in this Book may help guide the clinician in selecting the most desirable post system for each tooth.