Cysts of the Jaws

Question 1

What is a cyst?

Answer 1

A pathological cavity with fluid, semi-fluid or gaseous contents and which is not created by the accumulation of pus
Usually, but not always, lined by epithelium

Question 2

What makes up a cyst?

Answer 2

Wall = fibrous CT
Lumen = space where contents of cyst sits (fluid, semi-fluid or gaseous contents)
Lining

Question 3

Odonotgenic cyst WHO classification?

Answer 3

Odontogenic cysts of inflammatory origin

• Radicular cyst
• Inflammatory collateral cysts

Odontogenic and non-odontogenic developmental cysts

• Dentigerous cyst
• Odontogenic keratocyst
• Gingival cyst
• Lateral periodontal cyst
• Glandular odontogenic cyst
• Calcifying odontogenic cyst
• Orthokeratinised odontogenic cysts
• Nasopalatine duct cyst

Question 4

How common are cysts in adults?

Answer 4

Cysts 2nd most common type of lesion (mucosal 1st)

Question 5

Jaw lesions: most to least common?

Answer 5

Odontogenic cysts 70%
Odontogenic tumour 15%
Fibro osseous lesions 10%
Bone tumours 5%

Question 6

Cysts of the jaws classification?

Answer 6

Epithelial cysts
- Odontogenic: Inflammatory and developmental
- Non-odontogenic: nasopalatine duct cyst, nasolabial cyst
(non-odontogenic cysts linked to developmental process)

Cyst like lesions

Question 7

Classification of odontogenic cysts?

Answer 7

Inflammatory:

• Radicular
• Residual
• Collateral/paradental cysts

Developmental:

• Follicular cysts: Dentigerous cyst, eruption cyst
• Odontogenic keratocyst
• Gingival cysts
• Lateral periodontal cyst/botryoid odontogenic cyst
• Glandular odontogenic cyst
• Calcifying odontogenic cyst
• Orthokeratinised orthogenic cyst

Question 8

Position of cysts?

Answer 8

DIAGRAM
Apical radicular - around apex
Lateral radicular - side of apex
Lat periodontal - side of root next to crown
Dentigerous - around angled unerupted crown
Eruption - around unerupted crown
Nasopalatine duct - above central incisor crowns
Nasolabial - above lateral incisors
Residual cyst - not related to teeth
Keratocyst - often largest and most destructive, classic site = angle of mandible, large, irregular
Gingival cyst - adults - next to tooth lateral to crown
Alveolar cyst - infants - above unerupted crown (white nodules on alveolus - commonly mistaken for thrush)

Question 9

Frequency of jaw cysts?

Answer 9

Radicular 65%
Follicular 20%
Keratocyst 5%
Nasopalatine 5%
Others <5%

Question 10

Pathogenesis of jaw cysts - what do they need to develop?

Answer 10

Source of epithelium so they can get the lining

Stimulation for proliferation

Mechanism for growth and bone resorption so it can expand

• Differs between inflam and developmental cysts

Question 11

Where are the remnants of hertwig’s root sheath located?

Answer 11

In the periodontal ligament

Question 12

What are the sources of epithelium that help form a cyst?

Answer 12

• Radicular cysts = remnants of hertwigs root sheath
• Follicular cysts = reduced enamel epithelium
• Keratocysts, gingival cysts = Remnants of dental lamina (usually in retromolar area)

Question 13

What are cysts mechanism for growth and bone resorption?

Answer 13

• Osmosis and hydrostatic pressure results in growth of radicular and dentigerous cysts = cells in centre breakdown = hypertonic centre = water brought in to centre by osmosis = increasing hydrostatic pressure = unicentric expansion

Proliferation of the lining, especially in odontogenic keratocysts

Bone resorption by:
- IL-1 and IL6
- Prostaglandins
- Endotoxins from bacteria cause inflammation and activate T-cells = fibroblasts and KGF and FGFs stimulated
The above stimulate osteoclasts

Question 14

What are the stimuli for proliferation to help form a cyst?

Answer 14

- Inflammation:
Apical granuloma - radicular cysts
Periodontitis - inf lat periodontal cyst
Pericoronitis - paradental cyst 
- Developmental cysts:
Factors are unknown
Dentigerous cyst: eruptive force and profliferation? hydrostatic pressure?
Keratocyst: epithelial proliferation, hydrostatic pressure? tumour?

Question 15

What is a radicular cyst?

What are radicular cysts associated with?

Answer 15

Arise in the periodontal ligament from the epithelial rests of Malassez as a result of inflammation following death of the pulp
Always associated with a non-vital tooth

Question 16

Radicular cyst locations?

Answer 16

Apical:
- At the apex of a tooth associated with the opening of the root canal

Lateral:
- At the side of a tooth associated with a lateral branch of the root canal

Residual
- A radicular cyst which has persisted after extraction of the associated tooth

Question 17

What age group are more likely to have radicular cysts?

Answer 17

30-39yrs old

Question 18

Pathogenesis of radicular cysts?

Answer 18

Caries = non-vital pulp = periapical granuloma = proliferating odontogenic epithelium = radicular cyst

Question 19

What epithelium does a radicular cyst have?

Answer 19

Non-keratinised SS epi

Question 20

Pathology of radicular cysts?

Answer 20

Keratin 2%
Cilia 10% (hairy surface)
Hyaline bodies 10% (within epi)
Mucous cells 15%
Cholesterol 30% (crystals)

Question 21

How to differentiate a radicular cyst from a granuloma?

Answer 21

Cysts are:
Larger
More radiolucent
Well defined
Corticated outline
Painless
BUT only 50% are diagnosed pre-operatively

Question 22

How to differentiate a cyst and granuloma based on size?

Answer 22

Size less than a cm = more likely to be a granuloma
2cm = more likely to be a cyst
Larger = more likely to be a radicular cyst

Question 23

What is a collateral cyst: paradental cyst?

Answer 23

A cyst which arises on the lateral aspect of a tooth as a result of inflammation in a periodontal pocket
Arises from pocket epithelium
A particular type of paradental cyst arises at the buccal aspect of partially erupted molars
- Usually around partially erupted 8s, especially distobuccal aspect

Question 24

Paradental cyst histology?

Answer 24

Lining is v hyperplastic, SS non-keratinised epi