If a fleshy lump grows on the root of the gum and pus often spills out of it, this is a fistula hole. Fistulas are formed when a tooth has chronic periapical infection that is not treated in a timely manner, or when the patient has had the tooth killed but the root canal is not treated properly and the root tip of the tooth becomes inflamed. The alveolar bone is resorbed and fistulas and fistula holes are present. In such cases, it is important to re-treat the root canal, which has a probability of success of about 80%. If successful, the fistula and fistula holes will gradually disappear, the patient’s alveolar bone will gradually return to normal, and the tooth will be restored with a pile crown and can be used like a normal tooth.