Timely repair is needed. A knocked out piece of the tooth will cause the enamel to fall off, exposing the dentin. If the tooth is not repaired in time, the exposed position is very easy to have caries, and the caries is serious enough to injure the nerve of the tooth, which may develop into apical periapical inflammation. If a piece of tooth is knocked out, you need to go to the hospital as soon as possible to check whether the nerve is injured, and if the nerve is already exposed, you need to have root canal treatment and then repair the tooth. Currently, resin materials are used to fill the tooth, and the result is very beautiful and natural, and it does not affect eating after the filling. After root canal treatment, the tooth will become more fragile, you can choose to set the porcelain crown for repair, if the tooth has lost a small piece of the area is very small, and did not injure the nerve, just a simple filling can be repaired.