It is usually possible to have another root canal after root canal treatment. Root canal therapy is a treatment for endodontics periapical disease, removing the infected material from the root canal, achieving sterility in the root canal through root canal disinfection, and finally performing a tight root canal filling. If the root canal treatment is not perfect, apical inflammation recurs. Root canal retreatment can be performed. If the first root canal treatment leads to incompetent root canals, lateral penetration of the root canal wall, severe destruction of the pulp chamber floor, or root resorption caused by inflammation, root canal retreatment will be very difficult, or even root canal retreatment fails. Therefore, the possibility of retreatment after root canal treatment depends on the situation of the first root canal treatment, which needs to be determined after taking radiographs at the dentist.