Peri-Apical Cysts
What is a Peri-Apical Cyst?

A peri-apical (radicular) cyst is the most common tooth-derived cyst.

cyst is a sac-like structure (in this case) derived from tooth-related tissues.  It can be gas-filled, gel-filled or
blood-filled but normally it is not pus-filled (that is, it is not normally/initially infected).

What are the signs & symptoms?

Whilst small, the cyst is often not noticed.  When larger though, teeth can become mobile.  Cysts can become
infected and this can be when it is first noticed by either dentist or patient.
Photo of an excised peri-apical cyst (tooth already removed)
What are the causes of Peri-Apical Cysts?

The usual cause is a tooth that becomes infected with the result that the tooth dies.

Toxins from the dead
tooth-pulp exit the end of the tooth, leading to inflammation of the surrounding tissues. This
inflammation stimulates the cells found in the tooth-supporting structures, resulting in the formation of a
that may be infected or sterile.

Eventually, the
granuloma becomes a cyst.

These are not usually clinically detectable when small but are most often discovered as incidental findings on X-

How are they treated?

Several treatment options exist for such cysts.

cysts resolve with endodontic therapy (‘root canal treatment’) of the involved tooth.  Those lesions should be
monitored radiographically to ensure such resolution.

Cysts that fail to resolve with such therapy should be surgically removed and checked under a microscopic
analysis.  This is often accompanied by an ‘
apicectomy’ of the tooth involved.  This entails shaving off the end of
the tooth and sealing, preventing the recurrence of the
cyst (in theory).
Last Updated 13th June 2017
University of Arkansas, College of Health Sciences


Useful Articles:

Radiographics 1999.  Cysts & Cystic Lesions of the Mandible

Dental Update 2015.  Odontogenic Cysts - An Overview

Cysts of the Jaws.  University of Missouri-Kansas City School of Dentistry