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BDS4 Radiology > Odontogenic Cysts > Flashcards

Odontogenic Cysts Flashcards

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1
Q

What is a cyst?

A

Pathological cavity that is fluid filled, semi filled or has gaseous contents and no pus (unless infected)

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2
Q

Do cysts have epithelial lining?

A

Majority except

NON ODONTOGENIC OTHER CYSTS:

SOLITARY BONE CYSTS
ANYEURYSMAL BONE CYST

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3
Q

What are the majority of cysts?

A

Odontogeic (>90%of cysts in OMFS region)

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4
Q

What is an odontigenic cyst?

A

Cyst that is related to dental apparatus and has dental origin

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5
Q

Where does the epithelial lining of odontogenic cysts arise from?

A

Rests of Malassez

Rests of serres

Reduced enamel epithelium

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6
Q

What are epithelial cell rests of Malassez?

A

Odontogenic epithelial cells located within the periodontal ligament matrix.

Remnants of odontogenic epithelium remain in the periodontal ligament !!!!

While their function is unknown, they may support tissue homeostasis and maintain periodontal ligament space or even contribute to periodontal regeneration.

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7
Q

How can an odontogenic cyst form from epithelial cell rests of mallasez?

A

During tooth development there is inner and outer enamel epithelium which grows downwards forming epithelial root sheath of Hertwig which outlines TOOTH SHAPE AND FORMATION OF HARD TISSUE

Once root forms no need for this epithelium anymore and it normally degredades and dissolves but in some cases clumps of epithelial cells remain in PDL which remain static (they are vital but not active) and can be triggered to switch on (inflammation) resulting in cyst

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8
Q

What are rests of serres?

A

These are remnants of dental lamina epithelium entrapped within the gingiva.

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9
Q

How can odontogenic cyst form from rest of serres?

A

These are remnants of the dental lamina that once tooth formation is complete they are no longer needed and break up and disintegrate but in some cases they remain In jaw bones resulting in cysts

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10
Q

What is reduced enamel epithelium?

A

The epithelial covering of the enamel after its formation is completed.

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11
Q

How can reduced enamel epithelium lead to cyst formation?

A

After tooth formation when tooth is UE, the inner and outer enamel ep of tooth germ come close to each other forming reduced enamel ep which covers crown of UE tooth and as tooth pushes to erupt it breaks up but reduced enamel ep can be source of cyst

DENTIGEROUS CYST

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12
Q

What are the most common odontogenic cysts?

A

Radicular cysts (residual cysts) - 60%

Dentigerous cysts (eruption cysts) - 18%

Odontoegnic keratocysts - 12%

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13
Q

What is a radicular cyst?

A

This is an odontogenic inflammatory cyst associated with a NON VITAL TOOTH

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14
Q

What teeth are radicular cysts associated with?

A

non vital teeth

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15
Q

How can we be more inclined a cyst is radicular?

A

if tooth is grossly carious, likely non vital then consider this

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16
Q

Why do radicular cysts arise?

A

Tooth is non vital, necrotic products from pulp break down exist tooth at apex resulting in inflammation which can trigger cyst (inflammation can cause cells to activate)

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17
Q

When are radicular cysts most common in presentation?

A

4-5th decade - most common for caries and non vital teeth

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18
Q

Do radicular cysts affect males and females?

A

yes equal rates

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19
Q

Where do majority of radicular cysts occur?

A

60% maxilla
40% mandible

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20
Q

How might a pt present with radicular cyst? 6

A

Often asymptomatic

Pain (if secondarily infected)

Swelling (often buccal) - gradual expansion as slow growing)

Dislodgement of adjacent teeth (tooth may change position)

Pressure, numbness, altered sensation - if in region of nerve canal (IANC, mental nerve)

Tooth mobility

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21
Q

Do radicular cysts grow fast?

A

No, often slow growing and can grow for Long time to become large (have limited expansion)

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22
Q

What may a radicular cyst be rather than cyst?

A

Periapical granuloma

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23
Q

What is a PA granuloma?

A

A periapical granuloma is a relatively common lesion or growth that develops around the tip of a tooth’s root. It consists of a proliferating mass of granulation tissue (new tissue that forms on a wound) and bacteria that forms in response to dead tissue in the pulp chamber of the tooth.

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24
Q

How can we tell if its PA granuloma of radicular cyst?

A

Look at SIZE OF LESION!!
>15mm then 2/3rds are radicular cyst

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25
How can we get radicular cyst?
Pulp necrosis --> PA periodontitis --> PA granuloma --> radicular cyst
26
What are the radiographic features of radicular cysts? 6
Well defined margins Rounded shape Radiolucent Corticated margin of radiolucency that continuous with the Lamina dura - if we can follow the corticated margin with LD its good indication If large it displaces structures Resorption of root unlikely unless long standing then external root resorption
27
What is a good radiographic indication its a radicular cyst?
continuous with the lamina dura of tooth and corticated margin
28
Describe the histology of a radicular cyst
Fibrous CT wall and lined epithelium (stratified squamous ep, non-keratinised) Can contain cholesterol in fluid due to RBC breakdown
29
How can radicular cyst develop from granuloma (histology)?
This is due to epithelial cell rest of malassez which is present in the PDL, the tooth is non vital and there is necrotic debris which can activate these cells due to inflammation and they begin to divide within the granuloma resulting in centre of granuloma becoming cut off from blood supply --> necrosis --> cyst forming
30
Why do majority of cysts grow at same rate?
Path of least resistance of growth Osmosis - centre of cell draws in water by osmosis which causing pressure on surrounding bone resulting in resorption of bone and cyst continues to grow (activation of osteoclasts)
31
What are the two ways radicular cysts form?
Epithelium proliferates in granuloma resulting in central necrosis due to lack of blood supply Epithelium surrounds fluid area
32
Why can we get egg shell crack on palapation of a radicular cyst?
Cyst has thinned cortical bone and when we feel it it will crack slightly
33
What can radicular cyst do to cortical plate?
Thin and displace it
34
If we were removing a cyst why do we want a CBCT?
We want to see buccal/lingual expansion and proximity to important nerve structures - if layer of bone separating then theres a protection of nerve
35
Why is a rounded well formed lesion a good sign?
Good sign cyst isn't nasty! if cancer then often grows fast, fast eating of bone
36
What can give moth eaten appearance to bone?
Osteomyelitis
37
What is osteomyelitis?
(which is infection and inflammation of the bone marrow, sometimes abbreviated to OM)
38
If cyst is near mental foramen what are some symptoms pt will tell us of?
Tingling sensation Aletered sensation Numbness uncommon as cyst wont completely invaded nerve just press on space
39
If as a dentist we take PA and we can only see radiolucency partially what do we do?
OPT CBCT
40
What is the issue with OPTs for cysts?
Poor in midlinede to superimposition of cerical spine and spine base
41
What are the teeth symptoms of radicular cyst?
Mobility Spaces in dentition Titling of tooth Altered occlusion
42
What are some other symptoms of radicular cysts ?
Mental nerve Infra-orbital nerve -altered sensation to cheek, upper lip, lateral aspect of nose, below eyelid IAN Maxillary sinus - can obliterate this space leading to muffling sound/voice changes, pain when moving head, postal changes
43
How can we tell if maxillary sinus been affected?
Pain on postural changes Muffling sound of voice - blocked sinus affects voice
44
Can a cyst cause vision problems?
Can cause diplopia if large enough and pushing against floor of orbit
45
Can a cyst cause vision problems?
Can cause diplopia if large enough and pushing against floor of orbit
46
What is a residual cyst?
This is a variant of a radicular cyst that occurs after the tooth in question is extracted or if tooth has RCT
47
Why is it hard to provide if residual cyst of due to RCT?
Successful RCT and residual cyst Unsuccesful cyst = radicular cyst continuing
48
When may residual cyst form?
Pt has radicular cyst, we Xla tooth, and end up with residual cyst
49
What is a lateral radicular cyst?
This is when necrotic produce from pulp necrosis comes out of accessory canal resulting in lateral radicular cyst
50
What is an inflammatory collateral cyst
these are odontogenic, inflammatory cysts associated with VITAL TEETH There are two types: paradental cyst buccal bifurcation cyst
51
What teeth are inflammatory collateral cysts associated with?
Vital teeth
52
What is a parental cyst?
This is cyst that is associated with distal aspect of PE 3rd molar
53
What is a buccal bifurcation cyst?
Cyst on buccal aspect of molar teeth
54
What is the cause of inflammatory collateral cysts?
It is a simple cyst which rises from inflammation often due to residual bits of odontogenic epithelium (nonK SS)
55
What is a clinical presentation on an inflammatory odontogenic collateral cyst?
NOt ofte obvious can be detected on radiographs by chance or if tooth is moving (pt often notices this) well defined radiolucency, unilocular
56
What vies does PA show?
Anterior posterior view Superior inferor doesn't show buccal lingual extension !!
57
What is a buccal bifurcation cyst?
Cyst that occurs at buccal bifurcation usually for first molar sign is that teeth titled and root goes lingually and crown goes buccaly so lingual cussp tend to go up way affecting occlusion
58
What is a dentigerous cyst?
This is an ODONTOGENIC, DEVELOPMENTAL CYST that is associated with CROWN OF UNERUPTED USUALLY IMPACTED TOOTH
59
What is dentigerous cyst usually to do with?
Crown of unerpted usually impacted tooth
60
What causes dentogerous cyst?
Cystic change of dental follicle
61
When are dnetigerous cysts most common?
2nd-4th decate M>F Maxilla more common due to 3rd molar impaction
62
How do dentogerous cysts appear on radiographs?
Large well defined corticated radiolucency that is around the crown of tooth Corticated margin attaches to ACJ of tooth (this is where dental follicle attaches) Can get very large as it expands and can envelope root of tooth if going downwards) Can displace teeth (teeth will move ue to being pushed by cyst) so tooth will look like its in weird location Can affect other structures such as maxillary sinus, IAN canal
63
If pt had dentigerous cysts what are their complaints?
May complain of tingling, altered sensation or numbness due to damage to IAN (TO LOWER LIP) No pain often just change in sensation (lower lip is numb or tongue)
64
What can cause a numb lower lip?
Cyst (denigerous, OK) Trauma Tumour Infection Fracture of mandible Damage to IAN after XLA iatrogenic damage to nerve by needle
65
Are dentigerous cysts symmetrical?
Initially but can become asymmetrical as they expand unilaterally when large
66
What is the lining of a dentigerous cyst?
non K stratified squamous ep
67
Main signs of dentogerous cyst?
Cyst that is continuous with ACJ of unerupted usually impacted tooth more common in mandible due to M3M
68
What may a dentogerous cyst actually be?
Can be enlarged follicle- need to consider this
69
Why can unerupted teeth have radiolucency over crown region?
Dye to dental follicle which remains until tooth erupts
70
How big is dental follicle normally?
up to 3mm in deminesion at crown
71
When do we consider area to be an enlarged follicle rather than dentigerous cyst?
4mm, symmetrical and even around crown
72
When may we consider cyst rather than enlarged follicle?
Dentogerous cyst if >4mm - consider monitoring Dentigerous cyst most likely and assume >10mm or if asymmetrical
73
What is one variation of dentigerous cysts'?
Eruption cysts
74
WHat is an eruption cyst?
benign cysts that appear on the mucosa of a tooth shortly before its eruption. They may disappear by themselves but if they hurt, bleed or are infected they may require surgical treatment to expose the tooth and drain the contents.
75
Where do eruption cysts occur?
Around crown of teeth that is erupting - usually just covered by soft tissue rather than within bone blueish appearance
76
Who gets eruption cysts?
Children - lots of teeth to erupt!!
77
Where are eruption cysts most common?
Incisors
78
What is a odontogenic keratocyst?
This is an odontogenic, developmental cyst that HAS NO SPECIFIC RELATIONSHIP TO TEETH (dental structure formation rather than tooth)
79
When are OKs common?
2nd to 3rd decade more common in males Mandible >mandible (POSTERIOR MANDIBLE CLASSIC PLACE!!)
80
Where are odontogenic keratocysts most common?
posterior aspect of mandible
81
What is the issue with OK?
Good news not cancer! but the problem with these cysts is that they have a high recurrence rate and have aggressive growth and damage we remove the cyst and often another OK will develop need 10 year radiographic follow up of pt
82
Why can't we enuculate an OK?
due to the characteristic nature of the cyst - it is aggressive growth and damage, high recurrence rate, multiloculated, invades lingual cortex we sometimes need to resect mandible
83
How does an odontogenic keratocyst appear?
Scalloped margins (rather than well defined we see undulations) 1/4 are multilocular often cause displacement of adjacent teeth huge risk of pathological fracture
84
How can odontogenic keratocysts often expand?
Can expand disgnificantlly mesio-distally before expanding buccal lingually (trabecular bone before cortical)
85
Why is histology so important for cyst dx?
We need to know what type of cyst it is as it. changes management If we have an odontogenic keratocyst then management is very different and follow up etc
86
How do we take sample of cyst fluid?
Cyst aspirate - which is wide bore needle biopsy to remove part of contents of cyst and Elaine it
87
How do we know.a cyst is an OK?
40g per litre of protein - LOW PROTEIN CONENT (normally >50 contains squames
88
Describe the histology of OKs?
Keratin present keratinised (para) strat squamous wavy corrugated ep with no rete pegs so so no strong attachment to underlying tissue and can detach easy Basal cell layer - palisading -all cells same height and nucleus all at same height
89
IF an odontoegnic keratocyst becomes infected what happens to the cell histology?
All characteristic features of OK disappear and wont be a specific looking cyst can often lead to pathologist wrongly dx cyst
90
Why do OK cysts recur?
Due to thin epithelial lining that breaks up quickly due to daughter cysts which are tiny keratyocust that occur within wall of main cyst and if left behind continues to grow the ep lining grows in clusters so certain part can grow quicker
91
Do we need to XLA teeth in OK cases?
Yes if in close connection with cyst or else increased recurrence rate
92
IF we see multiple cysts what must we think?
Syndrome such as goblin goltz syndrome (basal cell nevus syndrome)
93
What is basal cell nevus syndrome?
This is a syndrome where we get multiple OK cysts can also have other symptoms such as pitting on palms on hands soles of feet calcification of dura mater in younger children 15

BDS4 Radiology (2 decks)

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