Bone protrusion underneath the inner side of the teeth is usually associated with alveolar bone hyperplasia, odontogenic cysts, and apical periodontitis. 1. Alveolar Bone Hyperplasia: mainly refers to the bone hyperplasia protruding in the gingival area, which is usually related to chronic inflammatory stimulation, trauma, heredity and other factors. 2. Odontogenic cysts: mainly occurring in the periapical and gingival areas, when the cysts gradually increase in size, they will protrude from the surface, resulting in a protrusion of the bone underneath the medial side. 3. Periapical inflammation: usually associated with periapical inflammation, repeated inflammatory stimulation caused by purulent reaction, the formation of fistula, it will show a bone protrusion under the inner side of the tooth, when touched, there is obvious pain. If you find that the bone underneath the inner side of the tooth is protruding, it is recommended that you go to the hospital to take a picture in time to understand the situation, and if you need surgery, you should carry out surgical treatment as soon as possible.