Possible causes and treatment methods for severe pain, swelling or prolonged discomfort during or after treatment: 1, the root canal treatment process, the treatment instruments beyond the apical space damage the tissue around the root tip, resulting in tissue edema (pain after root canal preparation) 2, root canal preparation will be the root canal of necrotic tissue and bacteria pushed out of the apical hole, resulting in acute inflammation of the root tip (often the affected tooth although the nerve is dead 3, chemical periapical inflammation caused by drug leakage out of the apical hole during root canal disinfection (prompting patients to follow up on time during treatment) 4, apical bleeding during pulp treatment (stopping bleeding is crucial in one-time root canal treatment or pulp extraction under local anesthesia) The above cases need to be treated according to acute inflammation, with appropriate grinding of the tooth and systemic infusion of anti-inflammatory fluids, and then after the inflammation is eliminated. Treatment. For patients with root canal filling, they will gradually get better after treatment. 5. Missing root canal with infection. It is necessary to find the root canal that was missed and then do root canal filling treatment. 6. Need to do root canal filling treatment again 7, root canal filling when the adhesive exceeded the apical hole caused irritation to the root tip 8, chronic periapical inflammation apical inflammation can not be completely eliminated through root canal treatment The above two need to remove the apical inflammation through apical surgery 9, root bifurcation lesions can not be solved through root canal filling 10, periodontal pulp joint lesions – retrograde pulpitis The above two Need to do periodontal treatment, reduce the occlusion, such as really can not be retained can be considered extraction 11, the tooth itself has a hidden crack, although the perfect root canal treatment, but can not solve the affected tooth long bite pain. If the tooth cannot be retained, it should be extracted as soon as possible. 12. Due to the special location of the affected tooth, the root canal filling process may cause irritation to the inferior alveolar nerve when the instrument exceeds the apical hole or the root filling paste exceeds the apical hole. Use nerve-nourishing drugs, local physiotherapy and microwave treatment as soon as possible, and it will gradually improve after three months. 13. Problems of other surrounding teeth. Find other teeth and treat them as early as possible. In short, root canal filling treatment is a very complicated process, and it is inevitable that the doctor will have this or that problem during the treatment. Once there is pain or swelling, the patient should have enough trust in the doctor and give the doctor enough time, which often happens in the clinic. But after the doctor timely treatment, most of the affected teeth can be fully recovered, only a very few difficult cases, the doctor can not explain, for this kind of affected teeth I think can be systemic infusion control inflammation premise, can take the apical resection surgery, if really can not deal with the final end of the situation is to pull out, but must be distinguished from the trigeminal nerve pain.