Periapical Cyst Overview

Development of Periapical Cysts

• Initially, periapical cysts swell to a round hard protrusion, but later the body resorbs some of the cyst wall, leaving a softer accumulation of fluid underneath the mucous membrane.
• Secondary symptoms of periapical cysts include inflammation and infection of the pulp, causing dental caries and necrosis of the pulp.

Characteristics of Periapical Cysts

• Larger cysts may cause bone expansion or displace roots.
• Discoloration of the affected tooth may occur.
• Patients may present negative results to electric and ice tests of the affected tooth, but will be sensitive to percussion.
• Surrounding gingival tissue may experience lymphadenopathy.
• The alveolar plate may exhibit crepitus when palpated.

Complications of Periapical Cysts

• Expansion of the cyst causes erosion of the floor of the maxillary sinus.
• As the cyst enters the maxillary antrum, the expansion rate increases due to available space for expansion.
• Performing a percussion test by tapping the affected teeth will cause shooting pain, which is often clinically diagnostic of pulpal infection.

Causes of Periapical Cysts

• Periapical cysts are usually caused by root infection involving tooth decay.
• Untreated dental caries allow bacteria to reach the level of the pulp, causing infection.
• The bacteria gain access to the periapical region of the tooth through deeper infection of the pulp, traveling through the roots.
• The resulting pulpal necrosis causes proliferation of epithelial rests of Malassez, which release toxins at the apex of the tooth.

Stages of Periapical Cyst Development

• Initial stage: Epithelial cells from the rests of Malassez at the apex of the roots of a non-vital tooth become stimulated due to the body's inflammatory response to bacterial endotoxins infecting the pulp or as a direct response to necrotic pulp tissue.
• The cyst develops due to an inflammatory stimulus in 3 stages.

General Information

• Periapical cysts are commonly known as dental cysts and are the most common odontogenic cyst.
• They may develop rapidly from a periapical granuloma as a consequence of untreated chronic periapical periodontitis.
• Periapical cysts are usually located in the maxillary anterior region and are caused by pulpal necrosis secondary to dental caries or trauma.
• The cyst's lining is derived from the epithelial cell rests of Malassez, which proliferate to form the cyst.