The effects of not doing the crown are: 1, if the front teeth are missing more than 1/3 of the area without crown restoration, only by filling composite resin, the filling is easy to fall off when tearing and cutting food, along with the edge of the tooth tissue fracture may lead to pulp leakage, the large area of missing teeth will cause the retention force to become poor. 2, if not doing the crown, the filling in addition to easy to fall off, fracture, bite force is easy along the filling body 3. After root canal treatment, the tooth tissue will gradually become brittle and black, which will affect the beauty of the tooth, and only a crown can change the color of the tooth and prevent it from splitting.