Inability to open mouth may be caused by wisdom teeth pericoronitis, temporomandibular joint disorder disease, mandibular fracture, etc. It can be treated by medication, physical therapy and surgery under the guidance of doctor. 1. Wisdom teeth pericoronitis: It is one of the common oral diseases, often with symptoms such as limited mouth opening (jaw can not open the mouth), bad breath and fever. It can be treated by using iodized glycerin, cephradine capsules and other types of medications such as local rinses and antibacterial drugs, or by surgical methods such as pericoronary gingivectomy and wisdom tooth extraction. 2. Temporomandibular joint disorder: it may be caused by psychological factors, immune factors, etc. It often has symptoms such as pain, abnormal opening degree, etc., and there may be the symptom of inability to open the mouth with the chin. It can be treated by using pain-relieving and intra-articular injections such as ibuprofen tablets and sodium vitrate injections, or by physical treatment such as hot compresses and lasers. 3. Mandibular fracture: usually caused by trauma, etc. It usually has symptoms such as facial swelling, limited mouth opening (jaw can not open the mouth), facial asymmetry, etc. It can be treated by taking amoxicillin capsules. It can be treated by taking amoxicillin capsules, and if there is an open wound, it should be treated with antibacterial and tetanus-preventive drugs such as tetanus antitoxin and other types of medication, and by surgical methods such as manipulation and repositioning, traction repositioning, and intermaxillary fixation, and so on. If you can’t open your mouth because of muscle tension and teeth clenching after a trauma, you should be alert to the possibility of tetanus. It is recommended to consult a doctor in time to clarify the cause of the disease under the guidance of the doctor and then treat it.