Long-term non-healing ulcers may be caused by heavy recurrent aphthous ulcers, traumatic ulcers, cancerous ulcers and so on. 1. Heavy recurrent aphthous ulcers: also known as periungual aphthous ulcers, these ulcers have a longer healing time, and the ulcers are deeper and larger, and will leave a scar after healing. 2. Traumatic ulcers: this kind of ulcer is not removed due to the irritation of the stump and crown, so the ulcer continues not to heal. 3. Cancer ulcers: Because they are tumors, the ulcers grow larger and larger, and sometimes they are painful. There may be other reasons why the ulcers do not heal for a long time, so it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.