Oral root canal therapy is usually painless and can be performed with preoperative anesthesia for patients with pulpitis where the pulp is not completely necrotic. Root canal therapy consists of three major steps: root canal preparation, root canal disinfection and root canal filling. It is the treatment of choice for endodontitis and apical periodontitis, and is used to control tooth inflammation, prevent further progression of the disease and restore tooth function by cleaning out infected material from the root canal. In patients with apical periodontitis, the pulp is essentially necrotic and the root canal procedure is usually painless. In patients with pulpitis, the pulp is not completely necrotic and pain may occur during root canal preparation, requiring preoperative anesthesia, which usually provides significant relief. Root canal system is complex, it is recommended to go to a regular hospital stomatology department.