BDS4 odontogenic tumours

Question 1

What are the 3 groups of odontogenic tumours?

Answer 1

Epithelial
Mesenchymal
Mixed - epithelial and mesenchyme

Question 2

What is the first dental hard tissue to form?

Answer 2

Dentine - formed by odontoblasts
Mesenchymal in origin

Question 3

What is the concept of induction?

Answer 3

Only MIXED tumours can have dentine/ enamel formation
Presence of dentine is important for induction of maturation of ameloblasts and formation of enamel.

Question 4

Where are odontogenic tumours most likely to occur?

Answer 4

Most likely to occur in the jaw bones but some rare cases can occur in soft tissue

Question 5

How are odontogenic tumours often discovered?

Answer 5

Often incidental finding due to imaging to other reasons
Non-eruption of teeth
Late-stage bony expansion

Question 6

What % of oral/ maxillofacial lesions that are sent for histopathological assessment in the UK are odontogenic tumours?

Answer 6

1% - rare

Question 7

What are the most common odontogenic tumours of epithelial origin?

Answer 7

Ameloblastoma
Adenomatoid odontogenic tumour (AOT)
Calcifying epithelial odontogenic tumour

Question 8

What is a common type of odontogenic tumour of mesenchymal origin?

Answer 8

Odontogenic myxoma

Question 9

What is a common type of odontogenic tumour of mixed origin?

Answer 9

Odontoma/ odontome

Question 10

What are the characteristics of an ameloblastoma?

Answer 10

Benign epithelial tumour
Locally destructive but slow-growing
Typically painless
Most common in 4-6th decades
80% occur in posterior mandible
Characteristic pattern of growth - extends in every direction fairly equally.

Question 11

What are the 2 radiological appearances of an ameloblastoma?

Answer 11

Multi-cystic - 85-90% - typically more common in older patients

Uni-cystic - typically more common in YOUNGER patients

Question 12

What are the margins generally like in an ameloblastoma?

Answer 12

Well-defined, corticated
Potentially scalloped

Question 13

What are the effects an ameloblastoma can have on adjacent structures?

Answer 13

Displacement of adjacent structures - can push other structures out of the way e.g. teeth
Thinning of bony cortices
Knife-edge external root resorption - clean cut roots - not ragged like other lesions may be

Question 14

What is the management of an ameloblastoma?

Answer 14

Surgical resection with margin

Question 15

What is the most common radiographic presentation of an adenomatoid odontogenic tumour (AOT)?

Answer 15

Benign epithelial tumour

Uni-locular radiolucency with internal calcification around crown of unerupted maxillary canine

Margins well-defined & corticated/ sclerotic

Question 16

What is the common histology of AOT?

Answer 16

Distinctive with patchy calcification
Duct-like structure

Question 17

What is the common histology of ameloblastoma?

Answer 17

Ameloblast-like cells
Stellate reticulum like tissue
Fibrous tissue

Question 18

What is very characteristic of adenomatoid odontogenic tumour (AOT)?

Answer 18

Typically attached apical to ECJ - asymmetrical involvement of root and crown of the tooth

Question 19

Presentation of a calcifying epithelial odontogenic tumour (CEOT)?

Answer 19

Slow-growing but can become large
Half are associated with and unerupted tooth
Variable radiographic presentation

Question 20

Radiographic presentation of odontogenic myxoma?

Answer 20

Well-defined radiolucency
Soap-bubble appearance common for larger lesions
Smaller lesions unilocular

Slow growth along bone before causing notable bucco-lingual expansion

Question 21

Histological presentation of odontogenic myxoma?

Answer 21

Loose myxoid tissue with stellate cells

May contain islands of inactive odontogenic epithelium

Question 22

Management of odontogenic myxoma?

Answer 22

Curettage - scraped out

Resection - removal of bone and tumour

Depends on size

Question 23

Why is follow-up of treated odontogenic myxoma important?

Answer 23

High recurrence rate - 25%

Question 24

Describe an odontoma?

Answer 24

Benign mixed tumour
Malformation of dental tissue
Lie above inferior alveolar canal - similar to teeth
Surrounded by a dental follicle

Question 25

What are the 2 types of odontoma and describe each?

Answer 25

Compound odontoma - ordered dental structures - may appear as multiple “mini teeth” e.g. denticles
More common in anterior maxilla

Complex odontoma - disorganised mass of dental tissues
More common in posterior body of mandible