There are two types of abscesses: periodontal and periapical. A gum abscess (also called a periodontal abscess) usually is caused by an infection in the space between the tooth and gum. The infection may occur after food gets trapped between the gum and tooth. In people with severe periodontal disease, bacteria can build up under the gum and in the bone. A tooth-related abscess (also called a periapical abscess) occurs inside the tooth. This happens when the tooth’s nerve is dead or dying. This type of abscess shows up at the tip of the tooth’s root. Then it spreads to the surrounding bone. Most abscesses cause pain in the mouth, so patients usually seek treatment immediately. An abscess will not go away on its own and is always considered serious because the infection may spread to other parts of the body. Call your dentist for an appointment.