The edge of the post core crown should be placed 0.5 mm below the gingiva, and the edge must cover all root surfaces with smooth sealing. At the same time, we should do a good job of oral health education for patients to reduce complications. The height of the post core crown should be moderate. If the gingival distance is large, it can be slightly higher, otherwise it can be slightly lower. If it is too high, it will cause difficulties in tooth arrangement, and the strength of the denture base will be reduced. If it is too low, it will not achieve the retention effect. For some molars that cannot be restored with integral post core crown due to different root canal directions, split casting post core can be used, and the metal crown can be made by taking a mold after being cemented