Odontogenic Tumours

Question 1

Are odontogenic tumours mainly benign or malignant?

Answer 1

Mostly benign

Question 2

What are the symptoms of an odontogenic tumour?

Answer 2

Mainly asymptomatic - incidental finding
Pain is usually secondary to infection or pathological fracture

Question 3

What are the 3 main types of odontogenic tumours?

Answer 3

Epithelial
Mesenchymal
Mixed

Question 4

Which type of odontogenic tumours have enamel/ dentine formation present? Why?

Answer 4

Mixed tumours (epithelial and mesenchyme)
Due to the concept of induction:
- odontoblasts are mesenchymal- dentine induces the maturation of ameloblasts to form enamel

Cannot have enamel without dentine

Question 5

What are the 3 main sources of epithelium?

Answer 5

Rests of molasses (hertwigs root sheath)
Rests of serres (dental lamina)
Reduced enamel epithelium (enamel organ)

Question 6

What is an example of an epithelial odontogenic tumour?

Answer 6

Ameloblastoma

Question 7

What is an example of a mesenchymal odontogenic tumour?

Answer 7

Odontogenic myxoma

Question 8

What is an example of a mixed odontogenic tumour?

Answer 8

Odontoma

Question 9

What are the 2 most common odontogenic tumours?

Answer 9

Ameloblastoma
Odontoma

Question 10

What is an Ameloblastoma?

Answer 10

Epithelial odontogenic tumour
Locally destructive, slow growing
Most common in posterior mandible

Question 11

What is the Radiographic appearance of Ameloblastoma?

Answer 11

Multi cystic (most common) - may have thick curved septae
(Uni cystic in younger patients)

Well defined corticosteroid margins

Displacement of adjacent structures, thinning of bony cortices
Knife edge external root resorption

Question 12

What is a clinical characteristic finding of Ameloblastoma?

Answer 12

Expands in all directions
Hard bony swelling
Teeth not TTP

Question 13

What are the histological features of Ameloblastoma?

Answer 13

Follicular - islands of fibrous tissue
Plexiform - Ameloblastoma cells arranged in strands, no connective tissue capsule
Desmoplastic

Question 14

What is the management of Ameloblastoma?

Answer 14

Surgical resection with margin (1cm normal tissue)

Question 15

What is the recurrence rate of Ameloblastoma?

Answer 15

15%

Question 16

What is the malignant transformation of Ameloblastoma?

Answer 16

Very rare <1% cases
- ameloblastic carcinoma

Question 17

What is an adenomatoid odontogenic tumour (AOT)?

Answer 17

Benign epithelial tumour
Unilocular radiolucnecy with internal calcifications around the crown of unerupted maxillary canines. Often not symmetrical.
Causes impeded eruption

• anterior maxillary (Ameloblastoma= posterior mandible)
• spreads past CEJ

Question 18

What is the histological findings of AOT?

Answer 18

Distinctive patchy calcifications
Duct like structure

Well developed fibrous capsule surrounding cells - tumour removal is simple and recurrence is low

Question 19

What is calcifying epithelial odontogenic tumour (CEOT)?

Answer 19

Occurs most commonly in posterior mandible
50% associated with unerupted tooth

Radiolucency with internal radiopacities
- very variable presentation

Question 20

What is an odontogenic myxoma?

Answer 20

A benign mesenchymal tumour
Most common in mandible

Slow growing along bone before causing notable bucco lingual expansion

Question 21

What is the Radiographic presentation of an odontogenic myxoma?

Answer 21

Well defined radiolucency with thin corticated margins
Small lesions= unilocular
Large lesions= multilocular with scalloped margins (soap bubbles)

Question 22

What is the histological findings of an odontogenic myxoma?

Answer 22

Loose myxoid tissue with stellate cells
No capsule - locally invasive

Question 23

What is the management of odontogenic myxoma?

Answer 23

Curettage or resection (depending on size)
High recurrence rate (25%) so follow up.

Question 24

What is an Odontoma?

Answer 24

A benign mixed tumour
- malformation of dental tissue
- mature to a certain stage, can be associated with dentigerous cysts
- surrounded by dental follicle

Lie ABOVE inferior alveolar canal

Question 25

What are the 2 types of Odontoma?

Answer 25

Compound - appear as mini teeth (denticles), anterior maxilla

Complex - disorganised mass of dental tissues, posterior mandible