“Lateral periodontal cysts (LPCs) are defined as non-keratinised and non-inflammatory developmental

cyst A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble ...

s located adjacent or lateral to the

root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...

of a vital tooth.” LPCs are a rare form of jaw cysts, with the same

histopathological Histopathology (compound of three Greek words: ''histos'' "tissue", πάθος ''pathos'' "suffering", and -λογία ''-logia'' "study of") refers to the microscopic examination of tissue in order to study the manifestations of disease. Spec ...

characteristics as

gingival cyst Gingival cyst, also known as Epstein's pearl, is a type of cysts of the jaws that originates from the dental lamina and is found in the mouth parts. It is a superficial cyst in the alveolar mucosa. It can be seen inside the mouth as small and whiti ...

s of adults (GCA). Hence LPCs are regarded as the intraosseous form of the extraosseous GCA. They are commonly found along the lateral

periodontium The periodontium is the specialized tissues that both surround and support the teeth, maintaining them in the maxillary and mandibular bones. The word comes from the Greek terms περί ''peri''-, meaning "around" and -''odont'', meaning "tooth" ...

or within the bone between the

roots A root is the part of a plant, generally underground, that anchors the plant body, and absorbs and stores water and nutrients. Root or roots may also refer to: Art, entertainment, and media * ''The Root'' (magazine), an online magazine focusing ...

of vital teeth, around

mandibular In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

canines Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surn ...

and

premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...

s. Standish and Shafer reported the first well-documented case of LPCs in 1958, followed by Holder and Kunkel in the same year although it was called a periodontal cyst. Since then, there has been more than 270 well-documented cases of LPCs in literature.

Signs and symptoms

Observable clinical signs of a LPC include a small,

soft-tissue Soft tissue is all the tissue in the body that is not hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue connects, surrounds or supports internal organs and bones, and includes muscle, tendons, liga ...

swelling found just below or within the

interdental papilla The interdental papilla, also known as the interdental gingiva, is the part of the gums (gingiva) that exists coronal to the free gingival margin on the buccal and lingual surfaces of the teeth A tooth ( : teeth) is a hard, calcified stru ...

. However, as it is usually

asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered as ...

in nature, LPCs are usually detected through

radiography Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeuti ...

. On

radiographs Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...

, the LPC appears with a well-defined round, oval or sometimes tear-drop shape. It also has an opaque outline along the edge of the tooth root. In rare situations, possible implications include loss of enamel and

dentin Dentin () (American English) or dentine ( or ) (British English) ( la, substantia eburnea) is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by e ...

e of adjacent teeth, loss of

lamina dura Lamina dura is compact bone that lies adjacent to the periodontal ligament, in the tooth socket. The lamina dura surrounds the tooth socket and provides the attachment surface with which the Sharpey's fibers of the periodontal ligament perforate. O ...

and enlargement of the

periodontal ligament The periodontal ligament, commonly abbreviated as the PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which it sits. It inserts into root cementum one side and onto alveolar ...

space. Under the

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...

, the LPC is seen as a cystic cavity with a thin layer of epithelium along its margin and held up by a

connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tissue ...

. In most cases, no

inflammatory cell White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mu ...

cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

are present, but in some rare instances,

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

in the fibrous capsule can be observed. Many transparent cells rich in

glycogen Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body. Glycogen functions as one o ...

can found in either

plaque Plaque may refer to: Commemorations or awards * Commemorative plaque, a plate or tablet fixed to a wall to mark an event, person, etc. * Memorial Plaque (medallion), issued to next-of-kin of dead British military personnel after World War I * Pla ...

s or in the outermost epithelium layers. There is often thickening of the epithelium or plaque formation seen.

Formation/Pathophysiology

The origin of the LPC remains controversial, with extensive debate in the literature over the different hypotheses. Base on the findings, the pathogenesis of LPC may be related to three etiopathological hypotheses.

Reduced enamel epithelium

The hypothesis suggested that the

is lined by nonkeratinized epithelium reminiscent of the reduced enamel epithelium which is supported by

PCNA immunohistochemical expression Proliferating cell nuclear antigen (PCNA) is a DNA clamp that acts as a processivity factor for DNA polymerase δ in eukaryotic cells and is essential for replication. PCNA is a homotrimer and achieves its processivity by encircling the DNA, whe ...

Remnants of dental lamina

LPC histopathologically presents

-rich clear cells, which are also seen in the

dental lamina The dental lamina is a band of epithelial tissue seen in histologic sections of a developing tooth. The dental lamina is first evidence of tooth development and begins (in humans) at the sixth week in utero or three weeks after the rupture of the ...

. Therefore, LPC might be related to dental lamina remnants.

Cellular remnants of Malassez

The

epithelial cell rests of Malassez In dentistry, the epithelial cell rests of Malassez (ERM) or epithelial rests of Malassez (''pax epithelialis pediodontii'') are part of the periodontal ligament cells around a tooth. They are discrete clusters of residual cells from Hertwig's ep ...

(ERM) presented in the roots surface, principal location of the LPC, play a role in LPC formation. Several additional theories had been proposed regarding the origin of lateral periodontal cysts, including the possibility that the lesions may arise as a result of pulpal infection manifesting itself in a lateral position or chronic

periodontal disease Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main cau ...

activating the rests of Malassez.

Diagnosis, prognosis and predictive factors

Lateral periodontal cysts are

and are usually exposed in patients routine

. The onset of lateral periodontal cyst are insidious and subtle, with a yearly growth rate of 0.7 mm. Adjacent teeth

vitality Vitality (, , ) is the capacity to live, grow, or develop. More simply it is the property of having life. The perception of vitality is regarded as a basic psychological drive and, in philosophy, a component to the will to live. As such, peo ...

is of great importance when contemplating a pre-surgical working diagnosis of lateral periodontal cyst as missing adjacent teeth or past

endodontic Endodontics (from the ancient Greek, Greek roots ''endo-'' "inside" and ''odont-'' "tooth") is the Specialty (dentistry), dental specialty concerned with the study and treatment of the dental pulp. Overview Endodontics encompasses the study ...

treatment would affect and confuse the differential diagnosis. It is rare but have been reported in literature that cysts can display

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The ...

ry bone expansion, bone

perforation A perforation is a small hole in a thin material or web. There is usually more than one perforation in an organized fashion, where all of the holes collectively are called a ''perforation''. The process of creating perforations is called perfor ...

and overlying gingiva communication. Lateral periodontal cysts radiographically present as a rounded, teardrop shape that are usually less than 10mm in size, presenting with a uni-cystic well-delineated

radiolucency Radiodensity (or radiopacity) is opacity to the radio wave and X-ray portion of the electromagnetic spectrum: that is, the relative inability of those kinds of electromagnetic radiation to pass through a particular material. Radiolucency or hyp ...

. Lesions are situated usually between the tooth lateral surface between the root apex and alveolar crest. A prominent cortical boundary is also usually observed. Associated teeth root divergence and absorption is seldom observed, with loss of periodontal ligament space and

also possible. Lateral periodontal cysts have to undergo surgical removal by excision or

conservative enucleation Conservatism is a cultural, social, and political philosophy that seeks to promote and to preserve traditional institutions, practices, and values. The central tenets of conservatism may vary in relation to the culture and civilization in ...

, with post surgery radiographic follow up for several years, monitoring recurrence. Bone regeneration within the bony defect usually occurs from 6 months to 1 year. Recurrence is unlikely but have occurred and reported in literature. Root divergence due to lateral periodontal cysts are normalised or reduced after surgical treatment, without

orthodontic Orthodontics is a dentistry specialty that addresses the diagnosis, prevention, management, and correction of mal-positioned teeth and jaws, and misaligned bite patterns. It may also address the modification of facial growth, known as dentofacial ...

intervention required.

Squamous cell carcinoma Squamous-cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on th ...

development has been reported within literature to occur in lateral periodontal cysts.

Classification

Lateral periodontal cysts can be classified into two morphological types: Unicystic and Multicystic. Botryoid odontogenic cyst (BOC) was once classified as one type of LPC by Altini and Shear in 1992. It was opposed by Van der Waal in the same year as he stated that BOC extends well beyond the lateral area of root, therefore should not be considered as a variant of LPC. But it is possible that the cells of origin for both cysts are the same.

Treatment and management

Successful treatment of LPC consists of surgical removal of the lesion by conservative enucleation with guided bone regeneration technique (GBR) with

xenograft Xenotransplantation (''xenos-'' from the Greek meaning "foreign" or strange), or heterologous transplant, is the transplantation of living cells, tissues or organs from one species to another. Such cells, tissues or organs are called xenograf ...

and resorbable collagen membrane. This is often achieved without affecting the periodontal health of adjacent teeth. Periodic radiographic follow-up monitoring of the patient for any recurrence is also recommended. Typically, bone regeneration of the bony defect is achieved within 6–12 months, by placing an

osteoconductive {{Short pages monitor