Boulder teeth are generally referred to as molars. If half of a molar tooth is lost, it is necessary to examine the tooth to determine whether it can be retained, and to treat it with extraction or crown restoration after root canal treatment. 1. If there is no obvious loosening of the tooth, the bottom of the pulp cavity of the tooth is not penetrated, and the broken end is located on the gingiva, the tooth can usually be retained, and it is recommended that the tooth be restored with a crown after endodontic treatment, i.e., removing the infected pulp and the dentin wall in the root canal, and then filling, and then implanting a fiber post into the root canal to increase the tooth’s resistance to the force, and then restoring it with a crown. 2. If half of the molar tooth is lost, if the tooth is loose, the bottom of the pulp cavity of the tooth is penetrated, and the broken end is located under the gingiva, etc., it is usually recommended to extract the tooth and carry out restorative treatment after three months. It is recommended to go to the regular hospital stomatology department, the physician examination and comprehensive assessment, and then determine the treatment plan.