Lateral Periodontal Cyst of Tooth Periodontium

Lateral Periodontal Cyst of Tooth Periodontium

Lateral periodontal cyst (LPC), originates along the lateral periodontium from the cells of periodontal ligament, is a noninflammatory cyst on the lateral surface of the root of a vital tooth. Lateral periodontal cyst is generally asymptomatic and presents a round or oval uniform lucency with well-defined borders radiographically.


The lateral periodontal cyst is considered a developmental odontogenic cyst with unusual occurrence. In most cases it is preliminary diagnosed as a radiographic finding, presenting as well circumscribed or as a round or teardrop-shaped radiolucent area. Due to its location it can easily be misdiagnosed as a lesion of endodontic origin. Final diagnosis should be based on histopatological examination.

Lateral periodontal cyst is considered a developmental odontogenic cyst with unusual occurrences that may be associated with vital teeth. LPC represents approximately 0.8% to 2% of all odontogenic cysts.

Literature review shows that the lateral periodontal cyst is more prevalent in adults in the 5th - 7th decades, with mean age of 52 years, without preference for race or sex.

The most frequently reported location of lateral periodontal cyst is the mandibular premolar area, followed by the anterior region of maxilla.

Lateral Periodontal Cyst Causes|Etiology

Lateral periodontal cyst (LPC) is a noninflammatory cyst on the lateral surface of the root of a vital tooth. The etiology of lateral periodontal cyst is unclear and the cell rests of Malassez, reduced enamel epithelium or remnants of dental lamina were suggested to cause formation and development of lateral periodontal cyst.

The pathogenesis of lateral periodontal cyst may be related to the three etiopathological hypotheses: reduced enamel epithelium, remnants of dental lamina and cellular remnants of Malassez.

The first hypothesis is that the cyst is lined by nonkeratinized epithelium reminiscent of the reduced enamel epithelium which is supported by PCNA immunohistochemical expression.

The second theory is related to dental lamina remnants, based on the fact that lateral periodontal cyst histopathologically presents glycogen-rich clear cells, which is also seen in the dental lamina.

The third hypothesis offered that the epithelial remnants of Malassez presented in the roots surface, principal location of the lateral periodontal cyst, play a role.


It is rare in young people under 30 years and affects individuals between the fifth and seventh decade of life. LPC was reported not to have a predilection for any race.

Although some studies report equal sex distribution, others report male preponderance. LPC occurs more often in the mandible, especially on the lateral aspect of premolar-canine root surfaces.

Symptoms of Lateral Periodontal Cyst

The patients with lateral periodontal cyst are generally asymptomatic and lateral periodontal cyst is often identified during routine radiographical examination.

Some time a small, soft-tissue swelling found just below or within the interdental papilla. However, as it is usually asymptomatic in nature, diagnosis need a radiograph for confirmation

Lateral Periodontal Cyst Radiology

It appears radiographically as a round or oval uniform lucency with well-defined borders <1 cm diameter. The radiographic characteristics of lateral periodontal cyst are not pathognomonic and can resemble an odontogenic keratocyst or lateral radicular cyst.

Radiographically, the cyst presents as a well circumscribed round or teardrop-shaped radiolucent area (generally not exceeding 1 cm in diameter) with a radiopaque rim, located laterally to the root of a vital tooth.

The periodontal ligament space as a rule is not enlarged and there must not be a communication between the cyst's cavity and the oral environment.

Occasionally, lateral periodontal cyst may be multicystic, and called as odontogenic botryoid cyst due to macro- and microscopic features resemble to "bunch of grapes" (from the Greek word "botrios").

The radiographic features may be inconclusive relative to the diagnosis. Other interradicular radiolucencies must be distinguished from the lateral periodontal cyst: anatomic radiolucencies, such as the mental foramen, maxillary sinus and the nutrient canals; cyst of pulpal origin, other cysts of the jaws, odontomas and other tumours.

It may resemble a cyst that develops laterally through a side channel accessory in a non vital tooth. In a retrospective study of injuries of no endodontic origin, 3.8% cases of lateral periodontal cyst responsible for various treatments without success were found.

Lateral Periodontal Cyst Histology

Histologically, lateral periodontal cyst is composed of a cystic cavity with a connective tissue wall with nonkeratinized squamous epithelial lining of 1-5 cell thickness and is generally without inflammation.

Histologically, lateral periodontal cyst is composed of a cystic cavity with a noninflammatory /inflammatory connective tissue wall with fine nonkeratinized squamous epithelial lining.

The histopathology revealed that lateral periodontal cyst is a developmental cyst characterized by a thin layer of nonkeratinized epithelium with a thickness of 1 - 5 mm, which resemble the reduced enamel epithelium. Nonkeratinized squamous epithelium is composed of 1 - 5 layers of cells displaying a palisade distribution.

The epithelium lining can be rich in epithelial plaques composed of the clear fusiform cells rich in glycogen. Some areas of the epithelial thickening, referred to as plaques or theca, are commonly found, and the connective tissue subjacent to the epithelium exhibits a zone of hyalinization.

Inflammation is not a feature and the walls of the cyst consist of mature collagen fibrous tissue. However, it is possible to observe the histopathological variant of LPC - botryoid cyst, that should receive a greater attention considering the rate of recurrence and unusual presentation.

The botryoid cyst represents a histopathological variant which presents with multilocular cystic "grape-like" appearance in the bone. Histopathological findings shows multiple cystic spaces lined by nonkeratinized stratified squamous epithelium.

Untreated lateral Periodontal Cyst

Untreated odontogenic cysts may cause root resorption, tooth displacement, expansion, and pain.


Treatment of LPC includes removal of the lesion surgically by conservative enucleation and follow-up of the patient radiographically to monitor for recurrence.

Generally after the enucleation of the cyst, leaving the bone cavity to be filled spontaneously. Any endodontic treatment or periapical surgery of the affected teeth is unnecessary, if all proved vital.

Healing Period after removal of Lateral Periodontal Cyst

During the healing period of 6 months to 1 year, bone regeneration will occur within the bony defect and recurrences are uncommon.

On the other hand, different regenerative approaches, including guided tissue regeneration (GTR) technique combined with decalcified freeze-dried bone allograft (DFDBA) and platelet rich plasma (PRP) technique have been used in the treatment of intraosseous cystic cavities.

Lateral Periodontal Cyst Differential Diagnosis

Differential diagnosis is of importance, since misdiagnosis may lead to false or unnecessary treatment of the lesion. It is important that the clinicians are aware of odontogenic keratocysts occupying a lateral periodontal position frequently.

Keratocysts must be differentiated from the lateral periodontal cysts because of their aggressiveness and high potential for recurrence following surgical removal. In addition, gingival cyst, lateral radicular cyst, pseudocysts and radiolucent odontogenic tumors must also be considered in differential diagnosis of lateral periodontal cyst.

Care After Surgery

The patients are advised to be followed radiographically to monitor for recurrence and regeneration of bony defects. Clinical healing is acceptable without recurrence, except the scar formation because of vertical incisions of flap design, and radiopacity on the distobuccal site of the tooth number 12 is observed, due to stabilized graft material in the cystic cavity, after 6 months follow-up period.

Satisfactory clinical and radiographic outcome can be achieved in the treatment of LPC using the principles of GTR.


Den Tim

Practicing Dentistry for 20 years