An oral fistula, also called a gumboil, is when inflamed pus forms an abscess causing a pressure increase in the surrounding tooth area. If the accumulated pus has no pathway to drain, spontaneous drainage may occur over time through the bone next to the tooth root. This pathway through which the pus burrows is called a fistula.


A fistula can form for a number of reasons:

  • mouth trauma or injury
  • infection
  • result of surgery
  • congenital defect


Fistulas usually appear near the roof of the mouth or on the gum and can be difficult to detect. A fistula is called a parulis when it becomes an elevated nodule in the mouth’s surface, appearing like a small pimple. This pimple usually ruptures to form an opening.

Similar Conditions

A fistula can sometimes be mistaken for and oftentimes is the result of other oral conditions.

  • torus—Elevated and bony to the touch, tori don’t necessarily need to be treated or corrected.
  • impacted/uninterrupted tooth—If an impacted tooth becomes infected, a fistula can form.
  • tooth abscess/canker sore—Mouth sores, if left untreated, can lead to fistulas.


A fistula is usually recognizable by a dentist based on its appearance and extensive tests are not required. Treating a fistula requires antibiotics and possibly the extraction of the infected tooth that led to the fistula via a root canal surgery. Sometimes treatment also calls for draining the abscess that led to the fistula. This is usually followed by root canal surgery.

To have a fistula correctly diagnosed and treated, consult with a dentist as soon as possible.

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