For root canal retreatment, fillings are mainly removed by mechanical removal, chemical dissolution, and surgical treatment. 1. Mechanical removal: For underfilled or poorly filled root canals, it is recommended to use a fine root canal file to unblock the root canals first, and then use a specific root canal file to lift and remove them. 2. Chemical dissolution: For some dense root canals that cannot be unblocked, chloroform can be used to dissolve them and then remove the filling after unblocking. It should be noted that chloroform is carcinogenic, so be careful when using it and do not touch the oral mucosa. 3. Surgical treatment: for the filling beyond the apical foramen of the root canal retreatment, generally difficult to remove, if necessary, apical surgery, open the window to remove the inverted filling. Due to the complexity of the operation, it is recommended to go to a regular hospital stomatology department for consultation.