A fistula is an abnormal passage or communication, usually between two internal organs or leading from an internal organ to the surface of the body. In dentistry, there are three different types:

  1. Oroantral fistula: An opening between the oral cavity and the maxillary sinus
  2. Orofacial fistula: An opening between the cutaneous surface of the face and the oral cavity
  3. Oronasal fistula: An opening between the nasal cavity and the oral cavity

A fistula generally develops after trauma to the mouth, due to periodontal disease, or after the loss of teeth. It collects the puss and other waste from the infection that has developed due to these issues and when full, forms a small bump. This bump often ruptures spontaneously and without treatment though dental attention is usually required as it represents the presence of an underlying infection. Treatment may include cleansing of the infected areas and antibiotics.