Inability to open the mouth cheek pain may be due to temporomandibular joint disorder, acute wisdom teeth pericoronitis and so on. 1. Temporomandibular joint disorder is the most common disease in the maxillofacial region, the main symptoms are pain in the preauricular region, inability to open the mouth, opening the mouth popping and so on. Attention should be paid to avoid mental stimulation, overwork, regular life, less late at night, change the habit of unilateral food chewing, do not bite too hard things, do not open the mouth too much when yawning, and pay attention to the facial joint area to keep warm. 2. Acute wisdom teeth pericoronitis main symptoms are: redness and swelling of the soft tissues around the crown, pain, severe cases can appear limited opening of the mouth, swallowing difficulties, facial swelling, and even general discomfort, headache, temperature rise, etc., the treatment includes anti-infective (such as metronidazole, cefuroxime, and other medications), local cleaning, incision and drainage, and so on. There are many reasons for the pain in the cheeks of the open mouth, it is recommended to consult a doctor in a timely manner, do not self-medication to avoid delays in the condition.