Crowns are not clinically mandatory for root canal treatment, but are generally recommended for patients. 1. Root canal treatment requires opening and draining the pulp and blocking the nerve of the tooth, which subsequently needs to be restored with a crown under the guidance of a doctor. 2. Because after root canal treatment without wearing a crown, not to protect the tooth, the tooth will be easily broken, and will crack, and fall off on its own, which will affect the normal chewing, and will affect the relationship between the bite, the surrounding tissues will also have a certain impact on the periapical, alveolar bone and the maxillofacial region. Therefore, the doctor will recommend the patient to wear a crown after root canal treatment as required. The choice of crown restoration after root canal treatment must be examined first, and can only be done after the inflammation is completely eliminated, if there is currently inflammation, it is necessary to anti-inflammatory first.