The timing of having a residual root for secondary removal after extraction needs to be determined based on a variety of factors such as the location of the remaining residual root, the difficulty of extraction, and other factors. 1. Location: If the residual root is close to the maxillary sinus, inferior alveolar nerve canal and other special physiological structures, due to the higher risk of removing the residual root, it is recommended to take a CT to analyze and plan the extraction program before determining the method of extraction, and the process of extraction needs to be very careful to avoid causing the penetration of the maxillary sinus, the inferior alveolar nerve canal damage or compression and other undesirable consequences. 2. Difficulty of extraction: If the residual root position is low, or there is a large root bifurcation and root bending and other abnormalities, local anesthesia and then turn the flap to open the window to fully expose the trauma, and then with the clamp extraction method or the apical kinda to carry out the second removal. Tooth extraction should go to the regular hospital.