CLINICAL REPORT
Australian Dental Journal 2002;47:(3):262-265
Pericoronal radiolucencies and the significance of early
detection
CS Farah,* NW Savage†
Abstract
Pericoronal
radiolucencies
are
common
radiographic findings encountered in general dental
practice. They usually represent a normal or
enlarged dental follicle that requires no intervention;
alternatively they may represent a pathological
entity that requires appropriate management and
histopathological interpretation. A pericoronal
space of greater than 2.5mm on an intraoral
radiograph and greater than 3mm on a rotational
panoramic radiograph should be regarded as
suspicious. Although many pathological processes
may present radiographically as pericoronal
radiolucencies associated with unerupted teeth, the
most common is the dentigerous cyst. These lesions
may enlarge considerably if allowed to develop
unchecked, and have the potential for pathological
transformation. In this report we present four cases
of large pericoronal radiolucencies associated with
unerupted teeth, and highlight the importance of
early detection and management of such lesions.
Key words: Pericoronal radiolucency, dentigerous cyst,
dental follicle, case reports.
(Accepted for publication 26 November 2001.)
INTRODUCTION
The crowns of unerupted teeth are normally
surrounded by a soft tissue remnant known as the
dental follicle. Radiographically the follicle appears as
an homogeneous radiolucent space around the tooth
with a thin outer radiopaque border.1 Since cystic
change can occur in these follicles, it is important to
identify any developing pathology at an early stage.
Although other forms of pathology may present
radiographically as pericoronal radiolucencies
associated with unerupted teeth, the most common is
the dentigerous cyst.2
The dentigerous cyst, also known as the follicular
cyst, is the second most common odontogenic cyst, and
*Postdoctoral Research Fellow and Registrar in Oral Medicine and
Pathology, Oral Biology and Pathology, The University of Queensland.
†Reader in Oral Medicine and Pathology, The University of
Queensland, and Consultant Oral Pathologist, Royal Brisbane
Hospital, Brisbane.
262
accounts for approximately 15 to 20 per cent of jaw
cysts.2 However, in contrast to the more prevalent
inflammatory radicular cyst, it is a developmental cyst
that arises from the dental follicle and so encloses the
crown, and is attached along the cemento-enamel
junction (CEJ) of an unerupted tooth. It develops by
accumulation of fluid between the reduced enamel
epithelium, which lines the inner surface of the fibrous
dental follicle, and the crown.3 Dentigerous cysts may
grow to a large size before they are identified. Most are
diagnosed upon investigation of a tooth that has failed
to erupt, or as an incidental radiographic finding, as
they are usually not painful unless secondarily
infected.4 Many patients first become aware of the cyst
as a slowly enlarging swelling. This is common in
edentulous patients with retained unerupted teeth.4
Dentigerous cysts are defined as true developmental
lesions and so are most commonly associated with
impacted teeth, particularly the permanent mandibular
third molars and maxillary canines, and to a lesser
extent mandibular premolars and maxillary third
molars.3
Radiographically the cyst appears in association with
the crown of an unerupted tooth as a well-defined
unilocular pericoronal radiolucency with a well
corticated sclerotic margin, unless it becomes
secondarily infected. Occasionally trabeculations can
be seen giving the appearance of a multilocular lesion.
The cyst may involve adjacent teeth and cause root
resorption or displacement. Different variants of the
dentigerous cyst have been identified including the
eruption cyst,1 lateral dentigerous cyst, circumferential
dentigerous cyst,5 and the inflammatory dentigerous
cyst.6 Although most dentigerous cysts are solitary,
multiple cysts are found in association with nevoid
basal cell carcinoma syndrome and cleidocranial
dysplasia.1
The dentigerous cyst may enlarge and extend
posteriorly to involve major portions of the ramus, or
anteriorly into the body of the mandible to involve
roots of adjacent teeth. It can also expand into the
antrum displacing involved teeth posteriorly or toward
the orbital floor. In this article four cases of large
pericoronal radiolucencies are presented to highlight
Australian Dental Journal 2002;47:3.
Fig 1. A large multilocular radiolucency associated with the crown of
a horizontally impacted 48 which extends into the right ramus above
the mandibular foramen and into the posterior region of the right
mandibular body. The right inferior dental canal has been displaced
and is in close relation to the lesion.
the significance of early identification and management
of these lesions.
CA S E R E P O RT S
All cases reported in this article were referred to the
Oral Medicine Clinic at the School of Dentistry, the
University of Queensland, and managed surgically in
the Oral and Maxillofacial Surgery department.
Histopathological reporting of the surgical
specimens was carried out by one of the authors
(NWS).
Case No 1
A 25-year-old caucasian female was referred for
management of a large multilocular radiolucent lesion
in the right vertical mandibular ramus, above the level
of the mandibular foramen, angle and posterior aspect
of the body (Fig 1). The lesion was associated with an
unerupted and horizontally impacted 48 with the
crown facing posteriorly. There were no obvious signs
of 46 or 47 root resorption. Clinically there was no sign
of soft tissue swelling or cortical plate expansion and
no local symptoms or sensory deficit. A provisional
diagnosis of dentigerous cyst was made on the basis of
the pericoronal configuration of the lucency with
encirclement of the CEJ, and the patient was referred
for management. The cyst was removed surgically and
submitted for histopathological examination. The
larger of two soft tissue fragments measured
40⫻14⫻10mm and the smaller 22⫻15⫻5mm with the
lining attached to the CEJ of the 48. The sections
showed an inflamed cyst wall with a non-keratinized
epithelial lining of regular thickness with no abnormal
proliferation. In a few foci, hyaline bodies were
prominent in the epithelium. The histology was
consistent with a clinical diagnosis of dentigerous cyst.
Case No 2
A 37-year-old caucasian male was seen for review of
a unilocular radiolucency in the right vertical
mandibular ramus associated with an unerupted 48
Australian Dental Journal 2002;47:3.
Fig 2. A unilocular radiolucency in the right vertical mandibular
ramus associated with an unerupted 48. The tooth is displaced
inferiorly to the centre of the lesion that extends anteriorly to the root
of 45. The radiograph shows a contour change of the lower border
of the body of the mandible consistent with expansion and thinning
of the cortex. There is also advanced 45, 46, and 47 root resorption.
(Fig 2). The tooth was displaced inferiorly to the centre
of the lesion that extended anteriorly to the root of 45.
The radiograph showed a contour change of the lower
border of the body of the mandible compared with the
left side and there was advanced 47, 46 and 45 root
resorption. The medical history was non-contributory.
Clinically there was some swelling on the inferior
aspect of the right mandible with facial asymmetry. A
provisional diagnosis of dentigerous cyst was made
based on the relationship of the lucency to the
unerupted tooth. The cyst was surgically removed
along with the embedded 48. The molar was attached
at the CEJ to a pericoronal cyst measuring
30⫻20⫻20mm. The cyst contents were greyish and
glistening suggesting cholesterol crystal formation.
Histopathological examination showed a very lightly
inflamed cyst wall with a thin non-keratinized
squamous epithelial lining. One sector contained a
granulomatous focus containing necrotic cells,
cholesterol clefts, and a mixed inflammatory infiltrate
and phagocytic cells. The histology was consistent with
a diagnosis of dentigerous cyst.
Case No 3
A 20-year-old caucasian male was referred regarding
an enlargement of the vertical ramus and posterior
portion of the body of the right mandible. The patient
presented with pain in the 46 area, and clinical
examination revealed an enlarged ramus. Medical
history
was
non-contributory.
Radiographic
examination revealed two large multilocular cystic
lesions (Fig 3). The first was a thin walled large cyst in
the right ramus associated with the unerupted 48, and
the second in the body of the mandible associated with
the unerupted 47 separated by an incomplete bony
partition. Teeth 18, 28 and 38 were all unerupted. A
provisional diagnosis of two dentigerous cysts was
made. The lesions were surgically removed and
consisted of cystic areas, teeth, and a solid soft tissue
mass measuring 85⫻40⫻20mm. A separate specimen
consisted of bone and soft tissue measuring
15⫻5⫻4mm. Histological examination revealed three
distinct morphological patterns. In the tissues removed
263
Table 1. Radiographic features for early detection of
developing pericoronal pathology
1. Follicular radiolucency greater than 2.5cm in diameter.
2. Unerupted tooth with an enlarged follicular space which is not in
its normal eruption position.
3. Unerupted tooth with an enlarged follicular space and root
formation is complete.
4. Inferior border of the follicular space is visible across the neck of
the tooth.
Fig 3. Two large multilocular cystic lesions are seen in the vertical
ramus and posterior portion of the body of the right mandible. The
first cyst is located in the right ramus associated with the unerupted
48, with obvious expansion of the ramus. The second is located in the
body of the mandible associated with the unerupted 47, and extends
to the root of 45. There is possible 46 distal root resorption.
from the ramus, the microscopic features were those of
a dentigerous cyst with a thin non-keratinized lining
epithelium and a loosely textured uninflammed fibrous
wall. In one wall sector there were a few islands of nonproliferating odontogenic epithelium. The tissues
removed from the body of the mandible showed both
an ameloblastoma within the wall of a cyst and a solid
ameloblastoma. The lesion was very cellular and
infiltrative. There was also evidence of ameloblastic
tissues within the submucosa and the gingivae. The
histopathological diagnoses were that of dentigerous
cyst and ameloblastoma.
Case No 4
A 22-year-old caucasian female was referred for
assessment of a radiolucency in the angle and vertical
ramus of the left mandible (Fig 4). The patient
originally complained of pain in the posterior right
mandible, and a panoramic plain film revealed
extensive coronal decay or resorption of the 47, and a
horizontally impacted 48. Tooth 38 was impacted with
an associated radiolucency extending from the distal
root of 37 to the mid vertical ramus. There was no sign
of displacement or root resorption of 37.
Clinical examination excluded soft tissue swelling or
cortical plate expansion on the left side, and there were
no local symptoms or signs of sensory deficit along the
terminal distribution of the inferior alveolar nerve. A
Fig 4. A large unilocular radiolucency associated with an unerupted
and impacted 38. The radiolucency extends from the apex of the 37
mesial root to the mid vertical ramus.
264
provisional diagnosis of dentigerous cyst associated
with 38 was made on the basis of the pericoronal
configuration of the lucency with encirclement of the
CEJ, and the patient was referred for surgical
management. The cyst was enucleated intact with 38
and submitted for histopathological examination. The
specimen consisted of a larger portion attached at the
neck of the tooth and measuring 15⫻8⫻8mm, and a
smaller separate portion measuring 8⫻5⫻5mm. The
sections showed a cyst lined by a parakeratinized
squamous epithelium six to eight cells thick, with an
undulating epithelial surface and basal cell palisading.
The fibrous capsule was relatively uninflammed and
contained occasional daughter cysts. These features
were consistent with a diagnosis of odontogenic
keratocyst.
DISCUSSION
The large cysts presented in this report outline the
importance of early detection of pericoronal
radiolucencies and appropriate management. If any
tooth, especially a mandibular third molar or maxillary
canine, is either missing, unerupted, impacted or out of
alignment, the underlying cause should be investigated.
This is recommended because of the speed with which
the cyst may enlarge, and to provide the tooth involved
with the best chance for eruption. Cysts developing in
the growing child will enlarge much more rapidly than
in the adult,7 and lesions 40 to 50mm in diameter can
develop in a three to four year period, although patients
may only give a history of a slowly enlarging swelling.8
The differential diagnosis of pericoronal
radiolucencies should include ameloblastoma,
odontogenic keratocyst, and other odontogenic
tumours such as adenomatoid odontogenic tumour in
anterior radiolucencies and ameloblastic fibroma in the
posterior jaws of young patients. Distinction should be
made between the widening of the follicular space that
normally accompanies eruption, and the early stages of
cyst formation (Table 1). This can undoubtedly present
a diagnostic dilemma when relying solely on
radiographic features.9
If a radiolucent cystic lesion is discovered, then
prompt referral for assessment and early surgical
intervention is warranted. If it is hoped that the tooth
will erupt, then marsupulization of the cyst may be
appropriate. This will allow free drainage of the liquid
content of the cyst, shrinkage of the cyst sac, and new
bone formation on its capsular aspect.7 However, the
most applied approach for the surgical removal of
Australian Dental Journal 2002;47:3.
dentigerous cysts is enucleation of the entire cyst
including both the epithelial layer and the capsule with
appropriate management of the resultant dead space.7
If dentigerous cysts remain without appropriate
treatment, they can become increasingly large in size
and continue to expand uninhibited. This makes future
management strategies more complex, increases the
risk of pathological bone fracture, and compromises
adjacent dento-alveolar structures. Dentigerous cysts
appear to have a greater tendency to cause root
resorption of adjacent teeth compared to radicular
cysts or odontogenic keratocyst.4 This may be derived
from the potential of the dental follicle, from which the
cyst originates, to resorb the roots of the deciduous
teeth.10 Transformation of the epithelial lining of the
cyst into an ameloblastoma is also possible, as is rare
carcinomatous transformation.2
While most dentigerous cysts seen commonly in
relation to unerupted teeth in both the maxilla and the
mandible are comparatively smaller in size than the
ones presented here, it is clear that they can achieve
significant dimensions and cause marked tissue
destruction. It is crucial then that the clinician fully
investigate all teeth that fail to erupt at the expected
time, and promptly initiate appropriate assessment and
management of suspected cystic lesions.
REFERENCES
1. Wood NK, Goaz PW, Schwartz LJ. Pericoronal radiolucencies.
In: Wood NK, Goaz PW, eds. Differential diagnosis of oral
lesions. 3rd edn. St Louis: Mosby, 1985:357-378.
Australian Dental Journal 2002;47:3.
2. Regezi JA, Sciubba JJ. Cysts of the oral region. In: Regezi JA,
Sciubba JJ, eds. Oral pathology; clinical pathologic correlations.
3rd edn. Philadelphia: WB Saunders Company, 1999:288-322.
3. Kramer I, Pindborg J, Shear M. Epithelial cysts. In: Kramer I,
Pindborg J, Shear M, eds. Histological typing of odontogenic
tumours. 2nd edn. World Health Organization, Geneva:
Springer-Verlag, 1992:36-40.
4. Shear M. Dentigerous (follicular) cyst. In: Wright, ed. Cysts of
the oral regions. 3rd edn. Oxford: Pergamon Press, 1992:75-98.
5. Mader C, Wendelburg L. Circumferential dentigerous cyst. Oral
Surg Oral Med Oral Pathol 1979;47:493.
6. Prabhu NT, Rebecca J, Munshi AK. Dentigerous cyst with
inflammatory etiology from a deciduous predecessor – report of
a case. J Indian Soc Pedod Prev Dent 1996;142:49-51.
7. Seward G. Treatment of cysts. In: Shear M, ed. Cysts of the oral
regions. 3rd edn. Oxford: Wright, 1992:227-256.
8. Seward G. Radiology in general dental practice. London: British
Dental Association, 1964.
9. Daley TD, Wysocki GP. The small dentigerous cyst. A diagnostic
dilemma. Oral Surg Oral Med Oral Pathol Oral Radiol Endod
1995;79:77-81.
10. Struthers P, Shear M. Root resorption produced by
ameloblastomas and cysts of the jaws. Int J Oral Surg
1976;5:128-132.
Address for correspondence/reprints:
Dr CS Farah
Oral Biology and Pathology
The University of Queensland
Brisbane, Queensland 4072
Email: c.farah@mailbox.uq.edu.au
265