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Definition: A radicular cyst is a cyst on the apex of a non-vital tooth

Clinical features

The age at presentation is wide, ranging from 20–60 years.

Radicular cysts are more common in males than females, roughly in the proportion of 3 to 2. The maxilla is affected more than three times as frequently as the mandible.

 These features reflect the frequency and location of non-vital teeth. Although deciduous teeth are often devitalised by caries, radicular cysts are rarely seen before the age of 10 years, probably because of the time required for them to form.

There is a slowly progressive painless swelling, with no symptoms until the cyst becomes large enough to be noticed. The swelling is rounded and at first hard. Later, when the bone has been reduced to eggshell thickness, a crackling sensation may be felt on pressure. Finally, part of the wall is resorbed entirely away, leaving a soft fluctuant swelling, bluish in colour, beneath the mucous membrane. The dead tooth from which the cyst has originated is (by definition) present, and its relationship to the cyst will be apparent in a radiograph.

 Infection may supervene because of the associated non-vital tooth, and the swelling becomes painful and may rapidly expand, partly due to inflammatory oedema.

Radiography

A radicular cyst appears as a rounded, radiolucent area with a sharply defined outline.

 A condensed radiopaque corticated periphery is present in slowly growing/chronic

 The dead tooth from which the cyst has arisen can be seen and often has a large carious cavity or other cause evident.

 Adjacent teeth may be tilted or displaced a little and can become slightly mobile as their bony support is reduced.

 

Sequela

Periapical abscess: pus discharge

Or

Periapical granuloma: Localized  mass of chronic granulation tissue containing PMN’s, lymphocytes, plasma cells.

Or

 Radicular cyst

Radiographic evidence may be

  • Radiographic indication of pulp exposure clinically test Non-vital
  • Widening of apical PDL or periapical radiolucency:rarefying osteitis
  • Discontinuity of lamina dura
  • Rarefying osteitis: radiolucency
  • Sclerosing osteitis/condensing osteitis: radio-opacity
  • Calcific degeneration

 

Radicular cyst: key features

  • Form in bone in relation to the root of a non-vital tooth
  • Arise by epithelial proliferation in an apical granuloma
  • Are usually asymptomatic unless infected or large
  • Diagnosis is by the combination of radiographic appearances, a non-vital tooth and appropriate histological appearances
  • Clinical and radiographic features are usually adequate for planning treatment
  • Do not recur after enucleation
  • Residual cysts are radicular cysts that remain after the causative tooth has been extracted
  • Cholesterol crystals often seen in the cyst fluid but are not specific to radicular cysts

 

 

Parulis (gingival abscess) in maxillary mucosa and representing pus extension from a periapical abscess

Palatal abscess representing extension of a periapical abscess

A rounded and sharply defined area of radiolucency is associated with the apices of the  caries /nonvital tooth root.

  

 Cysts range from a few millimeters to several centimeters in diameter, although most measure less than 1.5 cm. In long-standing cysts, root resorption of the offending tooth and occasionally of adjacent teeth may be seen.

Periapical lesion. (a) Conventional intraoral periapical radiograph of tooth 22. (b and c) Cross-section and axial cone-beam computed tomography image of the same tooth revealing the loss of palatal cortex. (c and d) Tangential and three-dimensional reconstruction image showing the dramatic extent of lesion. (e) Three dimensional reconstruction (surface volume) depicting the loss of bone in the labial cortex and the proximity of the lesion to the floor of the nasal fossa

Various sections depicting the cystic pathology in the maxillary anterior region. The dimensions of the cyst, extent of bone loss, labial cortical plate expansion, and thinning are markedly seen hence giving a clear picture about the lesion

Residual cyst

When the necrotic tooth is extracted but the cyst lining is incompletely removed, a residual cyst may develop months to years after the initial extirpation

Residual cyst associated at the site of an extracted tooth

Differential diagnosis

Radiographically, a differential diagnosis for periapical cyst must include periapical granuloma. In areas of previously treated apical pathology, a surgical defect or a periapical scar might also be considered. In the anterior mandible, periapical radiolucency should be distinguished from the earliest developmental phase of periapical cemento-osseous dysplasia. In the posterior quadrants, apical radiolucencies must be distinguished from a traumatic bone cyst. Occasionally, odontogenic tumors, giant cell lesions, metastatic disease, and primary osseous tumors may mimic a periapical cyst radiographically. In all of these considerations, associated teeth are vital.

 

Dentigerous cyst

The dentigerous cyst is a cyst around the crown of an unerupted tooth, with the epithelial lining attached around the cemento-enamel junction.

 Panoramic radiograph:  impaction of the right mandibular third molar and a large, well-defined radiolucency surrounding its crown and involving the distal root of the adjacent second molar.

  

Clinical features

Dentigerous cysts are more than twice as common in males as females, between the ages of 10 and 30 years. .

Two-thirds develop on lower third molars. Upper canines and lower premolars are also affected, reflecting the most frequently impacted teeth.

 They grow by internal pressure and cause the same clinical features as other cysts that expand the jaw; expansion with displacement of adjacent structures.

They are often a chance radiographic finding when the cause is sought for an unerupted tooth.

Radiography

The cavity is circumscribed, rounded and always unilocular and contains the crown of the tooth.

 Dentigerous cysts grow slowly and have a corticated outline.

Cysts may attain a very large size, larger than 10 cm, and large cysts may appear to be multilocular on radiographs (pseudoloculation) because bony ridges on the inside of the bony cavity are superimposed on the image.

 The affected tooth is often displaced a considerable distance, lower third molars to the lower border of the mandible or high in the ramus.

 In longstanding cysts, the enclosed tooth may become resorbed.

 

A panoramic view demonstrates a dentigerous cyst in an adolescent enclosing the permanent right mandibular impacted canine.

Possible complications

Extensive bone destruction with growth

Resorption of adjacent tooth roots

Displacement of teeth

Neoplastic transformation of lining (rare)—ameloblastoma formation; carcinoma very rarely

A, Dentigerous cyst exhibiting cortical expansion. B, A large dentigerous cyst of the right maxilla. C, An axial computed tomography (CT) scan of an expansile maxillary dentigerous cyst and associated impacted tooth.

Intraoral examination with no clinical signs: No swelling, no tenderness, normal color mucosa and clinically absent third molar teeth at the region, bilaterally. (a) Right side. (b) Left side

 On cone beam computed tomography panoramic (a) Axial (b) and sagittal (c and d) reformations was showed two well-defined unilocular radiolucent areas surrounded by thin sclerotic border associated to third molars displacement. On the right side, it has 23.64 mm diameter (c) and on the left side it has 16.57 mm diameter (d)

Transoperative clinical images (a) right side, notice the big cavity surrounding the impacted tooth (b) Left cavity

Dentigerous cyst: key features

 

  • Arise in bone and contain the crown of an unerupted tooth, which is usually displaced
  • Are most frequently associated with unerupted third molars and canines
  • Clinical and radiographic features usually provide an accurate preoperative diagnosis but confirmation is histological
  • May be mistaken radiographically for an odontogenic keratocyst or ameloblastoma
  • Respond to enucleation or marsupialisation and do not recur after treatment

 

Differential diagnosis

A differential diagnosis of pericoronal radiolucency should include odontogenic keratocyst, ameloblastoma, and other odontogenic tumors.

 Ameloblastic transformation of a dentigerous cyst lining should be part of the differential diagnosis.

 Adenomatoid odontogenic tumor would be a further consideration with anterior pericoronal radiolucencies, and ameloblastic fibroma would be a possibility for lesions occurring in the posterior jaws of young patients.

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