When a tooth is lost and only the root is left, it is necessary to check the specific condition of the root. If the root is short and loose to a certain extent, there is no way to utilize and retain this type of root, so it is recommended to directly remove the root and apply a fixed prosthesis or removable prosthesis to restore the extracted tooth. If the root of the tooth is clinically very strong and has sufficient length, the root can be used to restore the tooth. The specific method is to carry out the root system of endodontic treatment first, so that the root in the gum tip of the filling to become a whole again, and then in the pulp of the tooth to play a core, in the core of the core of the core of the external production of a crown to the core of the core of the sleeve, the above method is known as the core of the core of the crown restoration.