Odontomes and Odontogenic Tumours

Question 1

Define tumour

Answer 1

A swelling or excessive growth of tissue

Not inherently malignant or something dangerous

Question 2

Define neoplasm

Answer 2

New (neo) growth (plasm) of tissue occurring outside of normal homeostatic mechanisms

May have histologically/cytologically immature or abnormal cells

Question 3

Define hamartoma

Answer 3

A mass of disorganised tissue native to its normal anatomical location

Histologically mature cells that are arranged in a disorganised manner

Question 4

Define malignant

Answer 4

A disease process with potential for impairing QoL and life expectancy. Will likely kill the patient if left untreated

Question 5

Define benign

Answer 5

A disease process with limited potential to impair life expectancy. If left untreated, it is unlikely to kill the patient but could persist/grow to impair QoL

Question 6

Define odontome

Answer 6

A hamartoma of the tooth forming tissues

An abnormal growth/mass of disorganised tooth forming tissue native to its normal anatomical location

Histologically, the cells that form these tissues will look normal but will be arranged in a disorganised manner

Question 7

List the 5 types of odontomes

Answer 7

Invaginated odontome

Evaginated odontome

Enamel pearl

Compound odontome

Complex odontome

Question 8

Briefly describe an invaginated odontome

Answer 8

Abnormal growth of tooth forming tissue. Essentially an infolding of tooth tissue.

Can present as something as simple as a deep cingulum pit. But this pitting process can also be much more severe, resulting in a channel running through the full length of a tooth

The more severe ones are sometimes referred to as a dens in dente, where you get invagination of the tooth tissue to the point where you get a tooth formed inside the tooth. These will have all the normal layers of tooth (enamel, dentine, pulp, cementum) arranged in the correct structural order and relationship to one another

Question 9

How would you treat an invaginated odontome that has resulted in a superficial cingulum pit?

Answer 9

Treatment will depend on the severity of the invagination and the patient’s ability to maintain OH in the area.

A shallow cingulum pit is unlikely to cause any issues as a PRF or a barrier to OH maintenance in the area, therefore a simple fissure sealant, if suitable could be used to prevent caries

Question 10

How would you treat an invaginated odontome that has resulted in a very deep cingulum pit?

Answer 10

The treatment will depend on how severe the invagination is.

In the more extreme circumstances, where we get a very deep pit, there is potential for food packing and subsequent decay (due to a combination of the PRF and poor OH in the region - as it would be difficult to clean a deep cingulum pit adequately), we can get a tooth that eventually becomes non-vital.

These teeth may need more destructive intervention or even complete removal, especially if they are abnormally shaped, and therefore do not function properly.

Question 11

Briefly describe an evaginated odontome

Answer 11

Abnormal growth of tooth forming tissue. Additional tooth forming tissue located on the outside of the crown of a tooth

Can be of varying severity e.g. just a little bit of extra dentine or enamel on the outside of the crown of a tooth or much bigger additions of tooth forming tissues (an additional cusp (talon cusp)

Question 12

Briefly describe an enamel pearl

Answer 12

Relatively common odontome (abnormal growth of tooth forming tissue)

Formed by the disruption of the enamel follicle which causes it to form a little pearl of enamel, usually at the furcation of a multi-rooted tooth

Question 13

Where are we most likely to see invaginated or evaginated odontomes?

Answer 13

Invaginated and evaginated odontomes are more common in anterior teeth, as well as maxillary teeth.

Most commonly see them affect the U2s but can be seen in any tooth

Question 14

Briefly describe a compound odontome

Answer 14

A mass or bag of little teeth

Contains the structural components of a tooth in the correct order (enamel, dentine, pulp, cementum). Has specific areas/parts which resemble the different tooth layers (enamel, dentine, pulp etc.)

Histologically appears much more organised than complex odontomes, with the enamel being laid down on top of the dentine and cementum being laid down the side of it

Radiographically, we will see that the mass is filled with tiny teeth with radiolucent lines that indicate the PDL space and radiolucent centres that indicate the pulp

Question 15

Briefly describe a complex odontome

Answer 15

A discrete disorganised mass of tooth forming tissue

Contains the structural components of a tooth (enamel, dentine, pulp, cementum) but it doesn’t appear to look like any particular structure as all the structural components are organised in a disordered manner. There is no differentiation between the enamel, dentine and pulpal components

Radiographically, we see a well defined radiopaque mass often with a radiolucent margin around it

Question 16

Odontomes can occur at any age but which age bracket is most commonly affected by them?

Answer 16

Adolescence

Question 17

Generally, how are odontomes (especially complex and compound forms) treated?

Answer 17

XLA

Question 18

Why do complex/compound odontomes need to be removed?

Answer 18

Can impede the eruption of teeth or lead to missing teeth

Can interfere with the orthodontic movement of teeth

Question 19

How are complex/compound odontomes usually discovered?

Answer 19

Usually found because a tooth hasn’t erupted

Or a tooth is missing

Or as a result of an X-ray taken as part of an orthodontic assessment (as they can interfere with orthodontic movement of teeth)

Question 20

Briefly describe an ameloblastoma and its features

Answer 20

Tumour (swelling or excessive growth of tissue) that originates from the dental lamina (tooth forming tissue)

Painless, slow growing expansile lesion

Locally aggressive/invasive but metastasis is very rare (not likely to spread to secondary sites and therefore not likely to kill an affected individual although it can significantly impair QoL)

Question 21

Why does an ameloblastoma need to be treated aggressively?

Answer 21

Recurrence more likely if not treated aggressively

Question 22

List the non-modifiable risk factors of an ameloblastoma

Answer 22

Ethnicity, 10x more common in Black African people

Age, most commonly affect those in their 40-50s

Question 23

Describe the radiological features of an ameloblastoma

Answer 23

Most commonly a multilocular radiolucency (can be unilocular), with evident bony expansion and damage to adjacent teeth (resorption).

More commonly seen in the mandible rather than the maxilla and posteriorly rather than anteriorly

Question 24

How are ameloblastomas classified?

Answer 24

Classified into 3 subtypes-

Follicular (histologically appears organised)

Plexiform (histologically appears quite disorganised)

Unicystic (presents much like a cyst)

Question 25

Both ameloblastomas and odontogenic keratocysts commonly present as multilocular radiolucenies? What radiological features may help us distinguish between them?

Answer 25

There will be bone expansion in an ameloblastoma whereas a keratocyst doesn't tend to cause significant bone expansion Ameloblastomas are also more likely to cause external resorption of associated teeth, whereas odontogenic keratocysts are less likely to do that

Question 26

How would a plexiform ameloblastoma present?

Answer 26

Slow growing, painless and expansile solid tumour within the bone. Histologically, will have a disorganised architecture

Question 27

How would a follicular ameloblastoma present?

Answer 27

Slow growing, painless and expansile solid tumour within the bone. Histologically, will have an organised architecture

Question 28

How would a unicystic ameloblastoma present?

Answer 28

Slow growing, painless, expansile lesion that presents like a cyst (well defined, corticated, unilocular radiolucency on a radiograph that may transition to become multilocular later)

Question 29

If an operation was undertaken to lift a flap, remove the bone and expose the area containing a suspected unicystic ameloblastoma, what are the 3 possible presentations we could find?

Answer 29

Once this area is opened up, we would find a cyst cavity instead of a solid mass of tumour. If this was sent to a pathologist following removal, the pathologist would find a cyst but in parts of the corner of the cyst, there may be a fond-like appearance with features of an ameloblastoma OR there may be a solid mass of tumour in one corner OR even some islands of tumour tissue going off into the stroma deep to the cyst wall lining. This would be the only way to determine between a cyst and a unicystic ameloblastoma

Question 30

How can we differentiate between a cyst and a unicystic ameloblastoma

Answer 30

Undertake surgery, lift a flap, remove the bone and expose the area containing the suspected cyst. Take a biopsy sample to send to a pathologist following removal. On examination, the pathologist would find a cyst but in parts of the corner of the cyst, there may be a fond-like appearance with features of an ameloblastoma OR there may be a solid mass of tumour in one corner OR even some islands of tumour tissue going off into the stroma deep to the cyst wall lining. This would be the only way to determine between a cyst and a unicystic ameloblastoma.

Question 31

Briefly describe the management protocol for an ameloblastoma

Answer 31

An ameloblastoma is not a cyst or a hamartoma but it is a locally aggressive neoplasm (benign tumour). The chances of an ameloblastoma recurring if it isn't treated properly are much higher (++) Following history taking, examination (E/O, I/O) and special tests (radiographs), if we suspect an ameloblastoma, we need to confirm the diagnosis by taking a biopsy. Once confirmed, we need to assess the extent of the ameloblastoma using radiographs or CT Then we need to treat the ameloblastoma with local resection (removal of the tumour with a margin of normal bone on either side) If the ameloblastoma is particularly large, we may also need to undertake reconstructive surgery following removal

Question 32

Apart from an ameloblastoma, what other odontogenic tumours can arise in the mouth?

Answer 32

Cementoma Cemental dysplasia Cemento-osseous dysplasia

Question 33

How are PA cysts treated? How likely are they to recur?

Answer 33

Enucleation (removal of the cyst in its entirety) RCT/XLA of associated tooth Unlikely to recur if properly treated

Question 34

How are odontogenic keratocysts treated? How likely are they to recur?

Answer 34

Enculeation with curettage (scraping the bone to make sure we get all the little remnants of cyst lining out) is the gold standard approach. Can also be treated with marsupialisation In some cases, a solution called Carnoy's solution (which fixes the tissues, kills the cells and makes the cyst much easier to remove) can be used High recurrence rate (+). As keratocysts are multilocular rather than unilocular, it may be a little bit more difficult to get all of the cystic tissue out with enucleation. To add, the cyst lining is very delicate so it is easy to leave a bit of it behind.

Question 35

What is Carnoy’s solution used for?

Answer 35

Sometimes used to treat an odontogenic keratocyst Fixes the tissues, kills the cells and makes the cyst much easier to remove

Question 36

How are oral cancers treated? How likely are they to recur?

Answer 36

Treated using a wide excision with a good margin of normal tissue. Because it is a cancer (malignant tumour), it has the potential to metastasise so we will also need to start thinking about treating the lymph nodes with either surgery, radiotherapy and possibly chemotherapy. May need to think about undertaking a reconstruction to reconstruct the primary site following removal as well Highly likely to recur (+++), if not treated properly

Question 37

Define cancer

Answer 37

A malignant tumour Swelling or excessive growth of tissue that has the capacity to impair QoL and life expectancy. If left untreated, the affected individual will likely die

Question 38

What odontogenic cyst type resembles an ameloblastoma on a radiograph?

Answer 38

Odontogenic keratocyst

Question 39

What tooth forming tissue is responsible for the formation of an ameloblastoma?

Answer 39

Dental lamina

Question 40

An ameloblastoma is a ______ ______

Answer 40

A benign tumour (swelling or excessive growth of) the dental lamina (a tooth forming tissue)