The situation of biting into a part of the mouth and forming an ulcer is clinically common, professionally known as traumatic ulcers, most often found on both sides of the cheek and the tongue. If this kind of ulcers appear once in a while, there is no need to worry too much, it can be healed naturally in 1-2 weeks and no special treatment is needed. However, if it is a certain part of the mouth, due to the sharp tooth tip or bad restoration caused by the continuous long-term traumatic ulcers, we must be alert. Because long-term traumatic ulcers have the risk of cancer, if the ulcer lasts longer than 1 month, it is necessary to go to a professional stomatology department for a pathological biopsy of the ulcer to check whether it is cancerous or not, and most importantly, it is necessary to eliminate sharp tooth tips or bad restorations to fundamentally prevent oneself from biting into the mouth.