Recurrent aphthous ulcers are the most common ulcerative damage in the oral mucosa. It is characterized by periodic recurrent attacks with varying intervals, ranging from short continuous episodes that start and end, to long intervals of 2 to 3 months. Ulcers tend to occur on the lips, tongue, and cheeks, but can also occur on the floor of the mouth, soft palate, and pharynx. A general dentist should be able to treat this disease, so you can go to a general hospital dentistry department. There is a special oral mucosa department in the specialized dental hospital to treat oral ulcers, so if you want specialized diagnosis and treatment, you can go to the mucosa department of the dental hospital. If, in addition to recurrent oral ulcers, there are also recurrent ulcers on the external genitalia, it may not be recurrent aphthous ulcers, but may be leukoarthrosis, which is a more serious rheumatic immune disease and requires consultation at the rheumatology department of a general hospital. Many problems of oral cavity are related to systemic diseases, so it is necessary to pay more attention to abnormal symptoms of the body and seek timely medical treatment in specialized departments. There are also many oral cancer manifested as ulcers with infiltrative growth. Hard lumps can be touched at the base and around the ulcers, with elevated and untidy edges and depressions in the middle, and granular bumps on the surface of the depressions covered with necrotic tissues, which are usually painless or painful after stimulation, and can have spontaneous pain when invading nerves. Therefore, ulcers that are more than 2 weeks long need to be closely observed, and those that do not always heal should be seen by the maxillofacial surgery department of the oral hospital.