Mouth pain when eating, the pain site is different, there may be different causes, such as may be caused by gum or tooth disease, may be caused by some inflammation of the oral mucosa and other causes, or nearby tissue diseases caused by the cause of the pain involved. 1. If some diseases exist in the gums or teeth, such as gingivitis, periapical periodontitis, dental caries and other etiologic factors, it will cause pain manifestations in the gums and teeth and other places. Due to the chewing force or temperature stimulation of the affected area when eating, then there is a possibility of significant pain symptoms. 2. If the pain occurs in the upper jaw, the side walls of the mouth, etc., the pain may be caused by oral ulcers. You can observe whether there is an ulcerated surface on the painful area. With ulcers on the oral mucosa, the pain can also be irritated by food or worsened. 3. Pain in the mouth when eating, but also alert to whether with the oral cavity near the tissue of some diseases, such as maxillary sinusitis, osteomyelitis of the jawbone, jawbone swelling, etc., can also be due to the development of inflammation, occupying lesions, and so on, and affects the neighboring tissues so that the pain occurs. The pain may be accentuated by the movement involved in eating. In addition, the causes of oral pain are more than one, it is recommended that patients go to the hospital stomatology department in time for the appropriate examination, to clarify the cause of the disease.