The pain in the right cheek when the mouth is opened wide may be caused by disease and muscle injury, or it may be the lesion of the temporomandibular joint. 1. the right side of the face in the external external force under the action of the blow, there is a local muscle damage, or chewing hard food, long time open mouth such as a bite off half an apple will lead to muscle damage will appear cheek pain. 2. Dental diseases may cause pain in the cheeks if the root tip inflammation violates the gap between the maxillofacial area and the gap is infected. Temporomandibular joint lesions, including temporomandibular joint disorders, temporomandibular joint trauma, etc., can cause pain in the cheeks. Therefore, the right side of the mouth opened wide cheek pain needs timely medical treatment, you can go to the stomatology department.