It is possible to put vitamin C on an ulcer and it is likely to relieve the symptoms of the ulcer and allow it to heal as soon as possible. Mouth ulcer is a common and incurable recurrent disease in dentistry, with typical recurrent, intractable and self-limiting characteristics. Even without special treatment, a single ulcer will have significant relief or even disappear in about 1-2 weeks, but will immediately recur again. It is very difficult to cure mouth ulcers clinically and requires attention to maintaining oral hygiene, regulating the mind and strengthening the immune system. In addition, the most important thing is to pay attention to the longer-term single-site mouth ulcers. If there are obvious hardening changes around the mouth ulcers, it is recommended to go to the local stomatology department for examination as soon as possible and perform pathological biopsy if necessary to prevent the occurrence of oral cancer.