A cracked incisor needs to be checked for the depth of the crack, if it only reaches the dentin layer, a cavity can be prepared and resin restoration can be done, if the crack reaches the pulpal cavity, root canal treatment is needed. 1. Cracks do not reach the pulpal cavity: Teeth hit by external forces can lead to cracks in the enamel, or cracks to reach the dentin layer, causing teeth sensitive to the outside world of hot, cold, sour and sweet, cracks in the enamel can be temporarily observed, not to be dealt with first. If the crack reaches the dentin layer, it is necessary to prepare a cavity and then fill it with resin, or restore it with veneer or crown. 2. Cracks to the pulp cavity: If the tooth’s crack is greatly, that’s why it can cause symptoms of pulpitis, it needs resin filling after root canal treatment and crown restoration to protect the tooth. The incisor knocked cracked a crack, it is recommended to go to the hospital in time to take pictures to check the depth of the crack, timely treatment.