1, ulcers in the mouth for a long time: general mouth ulcers can be healed in 2 weeks, if the mouth ulcers for more than 4 weeks is still not good, you need to go to the hospital for examination and treatment. 2, discoloration: general oral mucosa white spot surface is relatively smooth, but if the surface of the white spot becomes very rough, hard nodules, weeping, protrusion or granuloma of grains, this is a typical lesion. 3.Lumps: If a rapidly increasing swelling appears in the mouth, which does not subside after treatment or has the tendency to ulcerate, do not be paralyzed. 4, loose teeth: the appearance of asymptomatic loose teeth and most of the teeth in the mouth, often is the performance of jaw bone lesions in the oral cavity to open the moist deterioration. 5.Mouth opening restriction: After excluding the jaw joint lesion, the patient should consider oral tumor, such as maxillary posterior carcinoma and tongue root carcinoma, whose early manifestation is mouth opening restriction. 6. Bleeding: repeated bleeding in the oral cavity without obvious reasons; 7. facial palsy and lower lip numbness of unknown origin: the facial nerve penetrates from the back of the skull and governs facial expression through the parotid gland endings. Cancer in the parotid gland is likely to destroy the facial nerve first and cause the symptoms of distorted mouth and eyes. 8.Changes in tongue movement and sensation: The sudden appearance of limited tongue movement, slurred speech, pain when speaking and swallowing, or loss of perception or numbness of the tongue hemilateral should be identified as soon as possible.