It is common for a tooth with a crown to require root canal therapy. When it is determined by the general dentist and endodontist that the crown is sound and can be preserved, root canal therapy can be performed through a small hole made in the crown. Following completion of root canal treatment, a post and core is often placed inside the crown through the same small hole by the endodontist. The post and core provides a permanent seal for the treated root canal. The post and core also restores tooth structure beneath the crown that was removed during treatment. Core material is placed up to the biting surface of the crown. Core material is a very strong material that is intended to be underneath a crown; it does not have the same smoothness that regular dental fillings. For this reason, we recommend that patients who have a post and core placed through an existing crown return to their general dentist for a surface filling.