If it is located in the inner side of the mouth opposite to the maxillary second molar, it may be a normal opening of the parotid duct, one on each side and symmetrical, which can be felt with the tongue and is a normal physiological phenomenon. In addition, it may be caused by the proliferation of granulation tissue in the inner wall of the mouth or bacterial infection, etc. 1, granulation tissue proliferation: it may be caused by long-term and repeated friction when chewing, or it may be caused by the formation of dental caries or pulpitis in the adjacent teeth, resulting in the protrusion of a fleshy rib in the inner wall of the mouth. If the former does not affect the daily eating and speaking, it can continue to be observed. If it continues to increase in size, it can be treated by orthodontics or surgical removal. The latter should first treat the adjacent affected teeth or use root canal therapy to treat pulpitis, and the granulation tissue proliferation will also subside after the treatment of the primary disease, and if it still exists for a long time, surgical treatment can also be chosen. 2. Bacterial infection: such as Staphylococcus aureus, pneumococcus and other bacteria causing oral infection, can occur in the mucosa of the oral cavity wall on the erosion or ulceration, some also have a pseudomembrane, may feel as the oral cavity wall raised a The fleshy rib may feel like a raised rib on the inside of the mouth. Bacterial infections should be treated with appropriate antibiotics, procaine gargle for pain relief, or watermelon cream to promote recovery. In daily life, attention should be paid to maintaining oral hygiene, rinsing the mouth in time after meals, and appropriately increasing the intake of vitamin-rich foods, such as oranges, apples, tomatoes, etc.