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1

Odontogenic Cysts Definition

Cysts lined by odontogenic epithelium

2

Inflammatory Cysts

Reactive, result or inflammation

3

Developmental Odontogenic Cysts

Unknown origin, although each type of cyst is thought to
arise from an aberration occurring at some point along the
continuum of normal tooth development

4

Classes of Inflammatory Cysts

• Periapical (radicular) cyst
• Residual periapical (radicular) cyst
• Buccal bifurcation cyst

5

Periapical Radicular Cysts basics

Always arises from a tooth with a necrotic pulp
• Often asymptomatic

6

Periapical cysts radiographic features

• Loss of lamina dura
• Relatively well-circumscribed radiolucency surrounding the apex/root
• May reach a large size

7

Periapical cysts v granuloma radiographically

radiographically identical

8

What is the difference
between a cyst and a
granuloma?

The periapical granuloma is an accumulation of chronically inflamed granulation tissue seen at the apex of a nonvital tooth. The radicular cyst is a lesion that develops over a prolonged period of time within an existing periapical granuloma. A cyst, by definition, has an epithelial lining.

9

Treatment of periapical cysts

endodontic therapy on
the involved tooth, or extraction of the tooth with curettage of
the cystic space. If the lesion does not resolve, seriously
consider biopsy. Don’t keep re-treating the tooth…

10

Residual Periapical Cyst

Radiographically appears as an
oval or round lucency within the
alveolar ridge at the site of a
previous tooth extraction.
Histology is similar to the
periapical cyst… The clinical
history and radiographic
description that you provide are
necessary to diagnose this

11

Buccal Bifurcation Cysts

Often develops on the buccal aspect of the
mandibular first permanent molars
• Usually seen in children from 5 to 11 years of age
• Complaints of tenderness, swelling, foul-tasting
discharge
• Buccal periodontal pocket may form
• One third of patients have bilateral involvement

12

Buccal Bifurcation Cyst Radiographical présentation

Radiographs reveal
a well-circumscribed
lucency involving
the bifurcation and
roots

13

Tx of Buccal Bifurcation Cysts

Treatment consists of enucleation of the cyst
without extraction of the tooth. Complete
healing is usually seen.

14

Developmental Odontogenic Cysts

• Dentigerous Cyst
• Eruption Cyst
• Odontogenic Keratocyst
• Orthokeratinized Odontogenic Cyst
• Gingival (alveolar) cyst of the newborn
• Gingival Cyst of the Adult
• Lateral Periodontal Cyst
• Calcifying Odontogenic Cyst
• Glandular Odontogenic Cyst

15

Dentigerous Cysts basics

Defined as a cyst originating
from the separation of the
follicle from around the
crown of an unerupted tooth.
Fluid accumulates between
the reduced enamel
epithelium and the crown.
• Most common developmental
odontogenic cyst, making up
20% of epithelial-lined
gnathic cystic lesions

16

Clinical presentation of Dentigerous cysts

Most DC’s commonly involve
mandibular third molars,
followed by maxillary canines,
maxillary third molars, and
mandibular second premolars.
• There is a slight male
predilection. The DC is most
often diagnosed between the
ages of 10 and 30.
• They are usually
asymptomatic, and are
discovered incidentally during
radiographic exam.

17

Dentigerous cysts and bone expansion

Occasionally they may cause painless expansion of the bone upon
reaching a large size.

18

Dentigerous Cysts communicate with oral cavity

If a DC communicates with the oral cavity (partially erupted tooth
or adjacent periodontal defect), the cyst may become infected, with
subsequent pain and swelling experienced by the patient.

19

Dentigerous Cyst - Radiographic

• Usually unilocular radiolucency associated with the
crown of an unerupted tooth
• The cyst usually has a well-defined, thin, sclerotic
border

20

Radiographic presentation of an infected dentigerous cyst

• An infected cyst may show ill-defined borders
• Large lesions may appear multilocular due to persistence of bony
trabeculae
• Occasional tooth displacement, root resorption

21

Hyperplastic dental follicle v dentigerous cyst

Some clinicians allow 3-4 mm for a dental follicle. Anything bigger is
often a dentigerous cyst, but COULD also be an odontogenic
keratocyst, ameloblastoma, or another odontogenic entity. Biopsy
and histologic evaluation will provide the final diagnosis.

22

Dentigerous Cyst – Treatment and
Prognosis

• Removal of the unerupted tooth
• Enucleation of the cyst
• Large cysts may be marsupialized prior to
removal
• Excellent prognosis, low chance of recurrence
• Infrequent bad stuff: ameloblastoma, squamous
cell carcinoma, intraosseous mucoepidermoid
carcinoma

23

Eruption Cyst

• This is the soft tissue counterpart of the
dentigerous cyst. The associated tooth is only softtissue
impacted.

24

Eruption Cyst - Clinical

• This cyst is most often seen in children younger than age 10
• There is a soft, translucent swelling of gingiva located over the
crown of an erupting tooth.
• Blood may be present in the cyst fluid, giving a blue color to the
lesion.
• Eruption cysts usually involve permanent first molars or maxillary
incisors

25

Erruption cyst radiographically

Radiographically, the erupting tooth
appears normal. The soft tissue is seen
as a slightly radiopaque dome over the
involved tooth

26

Tx of eruption cysts

These cysts often
rupture
spontaneously with
eruption of the tooth
– treatment is usually
not necessary

27

Odontogenic Keratocyst Basics

OKC’s arise from cell rests of the dental lamina
• It is thought that they do not enlarge by increased osmotic pressure
within the lumen, but from unknown factors inherent in the
epithelium or cyst wall
• Sporadic and syndromic cases are associated with a PTCH tumor
suppressor gene mutation on chromosome 9q22
• 3%-11% of all odontogenic cysts are keratocysts

28

Odontogenic Keratocyst (OKC/KCOT) -
Clinical

• 60% diagnosed between age 10
and 40 years
• Slight male predilection
• Mandible, 60%-80% of cases;
propensity for posterior
mandibular body and ascending
ramus
• Usually asymptomatic
• May grow large, tend to grow in
an antero-posterior direction
with no bony expansion

29

Odontogenic Keratocyst (OKC/KCOT) –
Radiographic

• OKC’s display a
well-defined
lucent area with
smooth, often
corticated
margins
• They may
appear
multilocular

30

OKC and unerupted teeth

• Associated with an unerupted
tooth in 25% to 40% of cases
• Radiographically similar to
dentigerous cysts when
associated with an unerupted
tooth