Crowns are recommended after root canal treatment, mainly to increase the success rate of root canal treatment and prevent tooth fracture. 1. Increase the success rate of root canal treatment: The last step of root canal treatment is root canal filling, which fills the missing part of the tooth and the cavity with open pulp, but the filling is mainly chemically bonded to the tooth, so there is micro-leakage, and the penetration of oral saliva will increase the failure rate of root canal treatment. Crowns can basically isolate the leakage and increase the success rate of root canal treatment. 2. Prevent tooth fracture: Root canal treated teeth are usually accompanied by dental defects, coupled with the reduction of blood supply after treatment, the tooth will become brittle and insufficient support. Therefore, it is often recommended to make a crown to prevent the tooth from fracturing. It is recommended to go to a regular hospital stomatology department and follow the doctor’s advice.