A cyst is a pathological cavity filled with fluid, semifluid or gaseous contents. It is frequently lined by epithelium but not always. Dental cysts are of different types and can be classified as under.
Classification of Cysts
1. Epithelial Cysts
a. Developmental Cysts
• Odontogenic Cysts
• Non Odontogenic Cysts
b. Inflammatory Cysts
• Ridiculer cyst, lateral and apical
• Residual cyst
• Paradental cyst and mandibular infected buccal cyst
• Inflammatory collateral cyst
2. Non Epithelial Cysts
1. Also called follicular cyst.
2. Separation of the follicle from around the crown of an interrupted tooth leads to its origin.
3. It covers the crown of the tooth and is attached at its came to enamel junction.
4. Developmental cyst and its tissue of origin is reduced enamel epithelium.
5. Fluid accumulation between the reduced enamel epithelium and crown of an interrupted tooth leads to the formation of the dentigerous cysts.
1. Mostly in the age range of 10 -30 yrs
2. More common in males
3. More common in mandible.
4. It mostly involves interrupted mandibular third molars, though other sites such as maxillary canines, maxillary third molars and mandibular second premolars are also involved.
5. On examining clinically it reveals a missing tooth or teeth and mostly a hard swelling which results in facial asymmetry
6. It is asymptomatic, occasionally patient presents with pain or swelling
Central Type Dentigerous Cyst
Most common and it surround the crown of the tooth and the crown projects into the cyst
The Circumferential Dentigerous Cyst
Surrounds the entire crown but does not involves the occlusal surface, so the tooth may erupt through the cyst
The Lateral Dentigerous Cyst
Usually associated with mesioangular impacted mandibular 3rd molars where cyst grows laterally along the root surface and only partially surrounds the crown
It presents a well circumscribed unilocular radiolucency around crown of tooth
• odontogenic kerotocyst
• unicystic ameloblastoma
• CEOT (Pindborg tumor)
• Adenomatoid odontogenic tumour
• Eruption cyst
• Treated by surgical removal, which usually involves the tooth as well.
• Large cysts may be treated by marsupialization.
• The cyst lining should be sent for histologic examination because ameloblastomas have been reported to occur in the cyst lining.
• Also called as eruption hematoma.
• Develops as a result of separation of dental follicle from around the crown of an erupting tooth
• It is a developmental cyst.
• Tissue of origin is reduced enamel epithelium
• Mostly in children less than 10 yrs age.
• Seen as soft translucent swelling in the gingival mucosa overlying the crown of an erupting deciduous or permanent teeth
• any erupting tooth, 1st permanent molars and maxillary incisors are most frequently involved.
• Blue to dark red in colour due to presence of blood in the cystic fluid
• No treatment is necessary as the cyst often ruptures spontaneously ,permitting the tooth to erupt
• Surgically exposing the crown of the tooth helps in tooth eruption.
Odontogenic keratocyst (okc)
• Derived from the remnants of the dental lamina
• High recurrence rate.
• It is a developmental cyst.
• Tissue of origin is dental lamina
• Epithelium appears to have innate growth potential.
• Wide age range from infancy to old age
• Mostly in males
• 70-80% cases involve the mandible / ascending ramus
• Asymptomatic unless secondarily infected
• Enlarges in antero-posterior direction without causing gross bony expansion hence no swelling seen.
• Aspiration reveals a thick, yellow, cheesy material (keratin).
• An aspirate of less than 4.0 gm of soluble protein level is indicative of OKC.
• well demarcated unilocular or multilocular radiolucency with a scalloped, radiopaque margin
• May be associated with interrupted tooth.
• dentigerous cyst
• odontogenic myxoma
• adenomatoid odontogenic tumor
• ameloblastic fibroma
Treatment: Enucleation and curettage
Non-Odontogenic Developmental Cysts
• Derived from remnants of the inferior portion of the nasolacrimal duct.
• Exact origin is unknown. It may arise from the epithelial rests in fusion lines of the globular, lateral nasal, and maxillary processes or may be nasolacrimal duct
• Asymptomatic. Slowly enlarging soft tissue swelling obliterates the nasolabial fold
• Occurs in the region of the maxillary lip and base of ala, lateral to the midline
• are less than 1.5 cm
• Age ranges from 12 to 75 years, with a mean age of 44 years.
• Mostly in females.
• Soft tissue lesion located adjacent to the alveolar process above the incisors apices.
• Being a soft tissue lesion, plain radiographs may not show any changes.
• The investigation could include computed tomography (CT) or magnetic resonance imaging (MRI)
• The swelling caused by an infected nasolabial cyst may cause an acute dentoalveolar abscess.
• Nasal furuncle, if it pushes upward into the floor of the nasal cavity.
• Mucous extravasation cyst or acystic salivary adenoma
Treatment: Surgical excision
Nasopalatine Duct Cyst
• Also called as Incisive canal Cyst, Median palatine cyst
• Commonest of non-odontogenic cyst
• Derived from epithelial remnants of naso-palatine duct
• May develop at any age but most common in 4 – 6 decades
• Slow growing swelling with occasional salty taste discharge.
• Large cyst may cause mid palatine swelling
• Male: female ratio. 3:1.
• Radiolucent area with well defined margins.
• Heart shaped radiolucency
• Symmetrical about the mid line and sometimes shifted to one side
• Peri apical granuloma
• Radicular cyst
• Enucleation, preferably from the palate to avoid nasopalatine nerve.
• If cyst is large marsupialization.
Median Palatal Cyst
• Rare cyst develops from epithelium entrapped along the line of fusion of lateral palatal shelves of maxilla
• Occurs in the midline of posterior palate
• Presents as a firm or fluctuant swelling of the midline of hard palate posterior to the palatine papilla
• Occurs in young adults
• Radiographically shows well circumscribed radiolucency in the midline of the hard palate
• A midline radiolucency without clinical evidence of expansion is probably a nasopalatine duct cyst
Treatment: surgical removal
Inflammatory Odontogenic Cyst
• Also known as apical periodontal cyst, periapical cyst or root end cyst
• True cyst
• Epithelial lining is derived from epithelial rests of malassez
• Initially there occurs proliferation of epithelial rests in the periapical area
• It continues with epithelial mass increasing in size by division of cells on the periphery
• The cells in the central portion becomes separated further away from their source of nutrition which eventually degenerate become necrotic and liquefy. This forms an epithelium lined cavity filled with fluid.
• Long standing cyst may undergo an acute exacerbation of the inflammatory process – cellulitis – or form a draining fistula
• lamina dura lost
• Rounded radiolucency encircles the affected tooth apex
• Root resorption
• Usuallyinvolves molar teeth and appear as a radiolucent zone that surrounds the root and fills interradicular space at the bifurcation.
• Extraction of involved tooth
• Curettage of periapical tissue
Pseudo- Or Non-Epithelial Cysts
Solitary Bone Cyst
• Also known as Simple bone cyst, traumatic bone cyst, hemorrhagic bone cyst
• May be related to trauma
• represent hemodynamic disturbances in medullary bone
• Most common in long bones and rare in jaws.
• In children and adolescents
• Involves 2-3rd decades.
• Mostly in males.
• premolar and molar region in the mandible.
• Mostly asymptomatic
• Radiolucency seen.
• Regular outline common, prominent around and between the standing teeth
• well defined margin
Aneurysmal Bone Cyst
• Rare cyst of the jaws.
• Arise as primary lesion or secondary to bone disease
• Occurs in people less than 20 yrs
• post ramus region of the mandible
• Firm expansile swelling causes facial deformity
Radiographically: uni or multilocular with ballooned out appearance due to cortical plate expansion
• Surgical curettage
• Uncommon developmental anomaly of the mandible.
• Appears as round or oval well demarcated radiolucency between the premolar region and the angle of the jaw beneath the inferior dental canal
• Depression or concavity on the lingual aspect of the mandible
Soft Tissue Developmental Cysts
• Mucous extravasations cyst
• Mucous retention cyst
Mucous Extravasations Cyst
• In lower lip, cheek and floor of mouth.
• Young adults
• Presents clinically as a bluish or translucent submucosal swelling
• Traumatic rupture of minor salivary gland duct
Mucous Retention Cyst
• Almost never found in the lower lip
• Derived from cystic dilatation of a duct due to obstruction and lined by ductal epithelium
• No surrounding chronic inflammatory reaction
• Describes a swelling in floor of mouth which resemble a frog’s belly
• most ranula are mucous extravasation cysts
• ranula may extend through the mylohyoid muscle and present in the submindibular area or neck (plunging ranula)
• It is derived from the residues of the embryonic thyroglossal duct .
• Glands descends from foramen caecum of the tongue
• The residues usually get entrapped in the region of the hyoid bone where it can give rise to the cyst
• Very rare. located in floor of the mouth and the tongue
• Management : surgery
• Ectopic thyroid gland (on the tonuge) may be functioning
• Excision may affect the function of the gland
Dermoid and Epidermoid Cyst
Occurs at variable sites in the head and neck including, floor of mouth.
Present as intra-oral or submental swellings
Arise from entrappment of epithelium in the midline because of deranged fusion of mandibular & hyoid branchial arches
Asymptomatic and slow growing soft swelling in young adults.
Gingival Cyst of Infants
Also known as
• Gingival Cyst of Newborn
• Dental lamina Cyst of Newborn
• Epstein Pearls
• Bohn’s Nodules
• More common in new born infants
• Small, single or multiple keratin-filled cysts on the alveolus.
• Epstein's pearls — Along the midpalatine raphae,small keratin filled cysts/ nodules found probably derived from the entrapped epithelial remnants along the line of fusion.
• Bohn’s Nodules -- Small keratin-filled cysts/nodules scattered over the palate, mostly along the junction of hard and soft palate and derived from the salivary gland structures.
• arises from dental lamina
• Epithelial remnants of dental lamina, rests of serres have the capacity to proliferate, keratinise and form small cysts
• Parakeratinised stratified squamous epithelium & keratin fills the cyst cavity
• Because of pressure from the cyst the overlying oral epithelium maybe atrophic
Treatment: Once there contents are expelled they atrophy and disappear