DrRupak Sethuraman
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Introduction
Classification
Differential Diagnosis
Radiographic Techniques
Conclusion
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To know the classification of pericoronal
radiolucencies.
To know the differences between each of the
pericoronal radiolucencies.
Advice of relevant radiographs to achieve a
diagnosis.
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Pericoronal radiolucencies comprise those
lesions which cause radiolucency in the
coronal region of the tooth or teeth.
The teeth are usually not erupted or may be
clinically as covered by the cystic fluid under
the overlying mucosa.
1.
2.
3.
4.
Dentigerous cyst
Odontogenic keratocyst
Paradental cyst
Eruption Cyst
DENTIGEROUS CYST:
(Synonym - Follicular cyst)
Definition:
It can be defined as an odontogenic cyst that
surrounds the crown of an impacted tooth.
It is estimated that about 10% of impacted teeth have formed a
dentigerous cyst.
Pathogenesis:
It is uncertain but apparently it develops by accumulation of
fluid between the reduced enamel epithelium and enamel
surface resulting in a cyst in which crown is located within the
lumen.
Clinical features:
10- 50yrs (Peak 2nd decade)
 Male predilection.
Commonly involve:
Mandibular molars, Maxillary Canines, Maxillary Molars,
Supernumerary teeth.
The cyst is always associated with crown of an
impacted, embedded or unerupted tooth.
Most of them are Solitary. Bilateral or multiple
are in association with
Cleidocranial dysplasia
and Maroteaux-lamy syndrome.
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Expansion of bone with subsequent
facial asymmetry
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Displacement
of
teeth,
Root
resorption of adjacent teeth and
pain are subsequent sequelae (steps)
of continuous enlargement.
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Displacement of third molar such that
it comes to lie compressed against the
inferior border of the mandible.
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In case of a cyst associated with a
maxillary cuspid, expansion of
anterior maxilla often occurs and
resemble acute sinusitis or cellulitis.
Location:
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Epicenter above the crown of the
involved tooth
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Attached at
Cemento
enamel
junction
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Well corticated Margins
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Little
tendency
towards
scalloping
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Unicystic, some are multilocular
Periphery and shape
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Dentigerous
cysts
typically
have
well-defined cortex with a curved or
circular outline.
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If infection is present, the cortex
may be missing.
Internal structure

The internal aspect is completely
radiolucent except for the crown
of the involved tooth.
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The circumferential
dentigerous cyst
appears to erupt through the cyst as
“through the hole in a doughnut”
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The lateral dentigerous cyst occurs on
one side of the involved tooth.
Differential diagnosis:
o Ameloblastoma –
o soap bubble appearance
o Causes root resorption.
o
Calcifying Odontogenic Cyst
o Common in maxilla, cortical plate perforation
o
Adenomatoid odontontogenic tumor
o Anterior maxillary teeth, root divergence
o Cystic lining does not arise from CEJ
o
Odontogenic Keratocyst
o Mandibular ramus third molar region.
o Delayed Expansion so diagnosed very late.
Potential complications:
o Epidermoid carcinoma
o
Mucoepidermoid carcinoma
o
Mural Ameloblastoma
Management:
-Small lesions can be surgically removed.
-Large cysts are often treated by surgical drainage or
marsupialization.
Definition:
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A cyst derived from the
remnants of the dental lamina,
with a biologic behavior similar
to a benign neoplasm, with a
distinctive lining of 6-10 cells
in thickness & exhibits a basal
cell layer of palisaded cells & a
surface of corrugated
parakeratin.
It is named keratocyst because
cyst epithelium produces so
much keratin that it fills the cystic
lumen.
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Keratocystic odontogenic Tumor
Oral Oncology (2007) 43, 619–
620
 Epithelium
lining the OKC has innate growth potential, as in
a benign tumor. This difference in the mechanism of growth
gives OKCs a different radiographic appearance.
 Islands
of epithelium in the connective tissue may give rise
to satellite microcysts.
-They
occur in a wide age range, but most
develop during the second and third decades,
-Slight male predilection.
-Common site :
Mandibular ramus third molar region
-Asymptomatic, although mild swelling may
occur.
-No obvious swelling seen in these cases.
-Rarely paresthesia is noted.
-Pain may occur with
secondary infection.
-Aspiration may reveal a
thick, yellow, cheesy
material (keratin)
-High
propensity
recurrence.
for
Location
-Posterior
body of the mandible (90%
occur posterior to the canines) and
ramus (more than 50%).
-The epicenter is located superior to
the inferior alveolar nerve canal.
Periphery and shape:
-Well
corticated border unless they
have become secondarily infected.
-Smooth round or oval shape identical
to that of other cysts, or it may have
a scalloped outline.
Internal structure:
-Radiolucent.
-Some cases curved internal septa – multilocular appearance.
Effects on surrounding structures
-Propensity to grow along the internal aspect of
the jaws, causing minimal expansion.
-This occurs throughout the mandible except
for the upper ramus and coronoid process,
where considerable expansion may occur.
-OKCs can displace and resorb teeth but to a
slightly lesser degree than dentigerous cysts.
-The inferior alveolar nerve canal may be
displaced, inferiorly.
-In the maxilla this cyst can invaginate and
occupy the entire maxillary antrum.
Management:
 Surgical excision is the
treatment of choice.
 Marsupialization
 Enucleation and primary
closure
 Enucleation and packing
open
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Differential diagnosis:
o Dentigerous cyst
o Ameloblastoma
o Residual cyst
o Traumatic bone cyst –
o
o
More scalloped and very thin
borders, covers more than one
tooth.
Is anterior in location.
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Associated
with
partially
impacted 3rd molars
Result of inflammation of the
gingiva over an erupting molar
0.5 to 4% of cysts.
Clinical Features –
The involved region shows a
slightly erupting third molar,
where a part of cusp can be
seen.
Probe can usually pass through
the distal extent of the third
molar into the cystic lumen.
Cystic lumen is not totally
covered as in other cysts.
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Radiology
–
radiolucency seen in
the distal aspect of
the tooth with a well
defined cystic lining.
Cyst usually covers a
part of the crown
portion
and
not
necessarily
starts Differential Diagnosis –
1. Dentigerous Cyst
from the CEJ.
Treatment
Enucleation
2. Residual Cyst – especially
after extraction of third
molar.
– 3. Radicular cyst
4. Lateral Periodontal Cyst
It is a form of dentigerous cyst associated
with erupting deciduous /permanent
teeth in children.
Clinical features:
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These cysts are found in children of
different ages and occasionally in
adults if there is delayed eruption.
Deciduous and permanent teeth are
involved
frequently
anterior
to
permanent first molar.
It appears as a circumscribed fluctuant
often translucent swelling of the
alveolar ridge over the site of eruption
of the teeth.
When the cystic cavity contains blood
the swelling appears purple or deep
blue hence it is called ‘Eruption
hematoma.
Radiographic features:
o It may show soft tissue shadow and
usually
there
is no bone
involvement.
o
In some cases saucer shape
excavation of bone projecting into
cavity.
Treatment:
No treatment is necessary as the
cyst often ruptures spontaneously.
Surgically, exposing the crown of
tooth may aid the eruption process.
Any Questions?