Cysts of the Jaws 1 Flashcards
What is a cyst
A pathological cavity having fluid, semi-fluid or gaseous contents & which is not created by the accumulation of pus
-> almost all are benign
What is a cyst called if it contains pus?
Infected cyst- pus is not part of pathology
What makes cysts a diverse group of lesions?
Can be:
symptomatic or asymptomatic
Slow or Fast growing
Indolent or destructive
What are the signs and symptoms of cysts?
- Swelling
- Pain & Tenderness
- Gradual tooth movements/spacing
- Mobility
- Prevented tooth eruption
- Discolouration of the tooth
- Egg shell cracking noise on palpation
How do you know if the cyst is coming from odontogenic or from the periodontium?
Assess the vitality
-> If vital = coming from the periodontium
How do you decide which radiographs to take for a cyst?
Patient history
Clinical examination
Which initial radiographs are taken to investigate cysts?
Periapical radiograph
Occlusal radiograph (if larger)
Panoramic radiograph (if very large)
- Only use large if necessary (higher radiation dose)
- Don’t use for (esp upper) anterior cysts
- Lots of limitations as there is anatomical features superimposed
Which supplemental radiographs can be used to investigate cysts?
- Cone beam CT (CBCT)
- Facial radiographs
- PA mandible view
- Occipitomental view
-> important as these show proximity to surrounding anatomy
Which radiographic features of cysts should be assessed?
- Location
- Shape
- Margins
- Locularity- how many chambers (uni/multi/pseudo)
- Multiplicity- how many of them there are (single is most common)
- Inclusion of erupted teeth
What shape do cysts tend to be on radiographs?
Spherical or egg shaped
-> can stretch as it reaches cortical bone as there is less resistance (some may destroy cortex)
How do margins of cysts appear radiographically?
Usually well defined and corticated
-> unless infection
What is meant by pseudolocular?
Appears like this as it pushes up against other structures
What does multiple cysts suggest?
That they are occurring as a result of a syndrome
How is aggression of cyst predicted?
By looking at effect on surrounding anatomy
-> Displacement of cortical plates, adjacent teeth, maxillary sinus, IAC
What may occur to tooth roots due to chronic cysts?
Root resorption
How are cysts classified?
Structure- epithelium lined OR non-epithelium lined
Origin- odontogenic OR non-odontogenic
Pathogenesis- developmental OR inflammatory
Where are odontogenic cysts never found?
Above maxillary sinus
Below IDN
What are the developmental types of odontogenic cyst?
Dentingerous (eruption) cyst
Odontogenic keratocyst
Lateral periodontal cyst
What are the inflammatory types of odontogenic cyst?
Radiciular cyst (and residual)
Inflammatory collateral cyst
-> Paradental
-> Buccal bifurcation cyst
What are the developmental types of non-O cysts?
Nasopalatine duct cyst
What are the other types of non-odontogenic cyst?
Solitary bone cyst
Aneurysmal bone cyst
-> no-epithelial lining
What are the general features of odontogenic cysts?
Occur in tooth bearing areas
-> arise from tooth material (can be a follicle)
Most common bony swelling of jaws
-> 90% of all cysts in oral/maxillofacial region
All lined with epithelium
What are the epithelial remnants can lead to odontogenic cyst formation?
Rests of Malassez (radicular)
-> Remnants of Hertwig’s epithelial root sheath
Rests of Serres (OK)
-> Remnants of the dental lamina
Reduced enamel epithelium (Dentigerous)
-> Remnants of the enamel organ
What are the most common odontogenic cysts?
Radicular cyst
Dentigerous cyst
Odontogenic Keratocyst
What causes radicular cysts?
Associated with a non-vital tooth
-> Initiated by chronic inflammation at apex of tooth due to pulp necrosis
What are the epidemiological features of radicular cysts?
Usually occurs in 40-50s
M=F
60% in maxilla, 40% in mandible
How do radicular cysts present?
Often asymptomatic
Pain if they become infected
Usually slow growing with limited expansion
How are periapical granulomas and radicular cysts differentiated?
If diameter of radiolucency is >15mm
-> 2/3 of these are radicular cysts
*PA granulomas will respond to RCT
What are the radiographic features of radicular cysts?
Round/oval
Well-defined
Coricated- margin continuous with lamina dura of non-vital tooth
Larger lesions may displace adjacent structures
Long standing lesions
-> External root resorption
-> dystrophic calcification
How do radicular cysts appear histologically
- Epithelial lining (often incomplete)- NK stratified squamous
- Connective tissue capsule
- Inflammation in capsule
- Cholesterol clefts
- Mucous metaplasia
- Hyaline/rushton bodies (unique to odontogenic epithelium)- no clinical significance
What can cause rests of mallasez to start dividing in radicular cysts?
Endotoxins from bacteria
What is meant by unicentric and multicentric?
Unicentric- all parts expand at same rate
Multicentric- parts of epithelium are more active
-> finger like processes form and grow in AP direction (with less clinical swelling)
How do radicular cysts form?
Proliferating epithelium with central necrosis
Epithelium surround fluid area
How does continued growth of radicular cysts occur?
Osmotic effect with semi-permeable wall
Cytokine mediated growth
What is a residual cyst? (variant of radicular)
When radicular cyst around apex of NV toothl persists after loss of tooth/successful RCT
-> as an encapsulated collection of fluid
What is a lateral radicular cyst?
Radicular cyst associated with a lateral/accessory canal (not apex)
-> located at side
What is an inflammatory collateral cyst?
Inflammatory odontogenic cyst assicuated with vital tooth
-> encompasses paradental and buccal bifurcation (depends on location)
Where does a paradental cyst occur?
Typically occurs at distal aspect of partially-erupted mandibular third molar
Where does a buccal bifurcation cyst occur?
Typically occurs at buccal (buccal bifurcation) aspect of mandibular first molar
What is a dentigerous cyst?
Developmental odontogenic cyst associated with crown of unerupted (& usually impacted) tooth e.g. mandibular third molars, maxillary canines
-> Cystic change of dental follicle
What are the epidemiological features of dentigerous cysts?
Most common in 2nd-4th decades
Male > female
Mandible > maxilla
Most commonly assoc. with 8s as these are often unerupted/impacted
What are the radiographic features of a dentigerous cyst?
Corticated margins attached to ACJ
Larger cysts may begin to envelope root of tooth
Initially symmetrical- may expand unilaterally as it gets larger
May be evidence of displacement of teeth and cortical bone
What do patients complain of when they have dentigerous cysts?
Lip is numb- cyst pushes on IDN
Mobility of adjacent teeth
What are the histological features of dentigerous cysts?
Thin NK Stratified squamous epithelium lining
-> attached to ACJ of unerupted tooth
May look like radicular cyst if inflamed
What is the histological indicators of enlarged follicle?
Cuboidal epithelium
Walls have islands of lamina
How are dentigerous cysts distinguished from enlarged follicle?
Consider cyst if follicular space >4mm/ radiolucency is asymmetrical
-> Measure from surface of crown to edge of follicle
-> Assume cyst if >10mm
What is an eruption cyst?
Variant of dentigerous cyst (almost exclusive to children)
-> Contained within soft tissue rather than bone
Associated with an erupting tooth
-> More commonly incisors
What is an odontogenic keratocyst?
Developmental odontogenic cyst with no specific relationship to teeth (may be near or touching and does arise from tooth tissue)
What are the epidemiological features of OK?
- Most common in 2nd & 3rd decades
- Male > female
- Mandible > maxilla (3:1)
- Posterior > anterior
- Worse recurrence rate
What are the radiographic features of OK?
Scalloped margins
Often multilocular
Often cause displacement of adjacent teeth
Root resorption is uncommon
How do OK characteristically expand?
Enlarges markedly in medullary bone space before displacing cortical bone
-> significant mesio-distal expansion without bucco-lingual expansion
What are the pre-operative diagnostic tests for OK?
Cyst aspirate
-> should contain- squames and low protein content (<4g/dl)
What are the histological features of an OK?
Wall
-> daughter/sateillite cysts can be found (if these are left they will form a new cyst)
Epithelial lining- may be parakeratinised
-> No rete pegs in epithelium
-> Basal palisading- basal cells at same height
-> evidence of multicentric growth with finger like projections
Cavity- wavey appearance
How are OKs treated?
Marsupialisation
1. Cut a hole and allow it to drain slightly = reduces in size and moves away from the canal and reduces risk of mandibular fracture and can be removed easier.
2. Remove tooth too to prevent recurrence
3. Close monitoring for years post surgery
How does basal cell naevus syndrome present? (aka Gorlin-Goiltz/Bifid rib syndrome)
Multiple odontogenic keratocysts
Multiple basal cell carcinomas
Palmar & plantar pitting
Calcification of intracranial dura mater
How does basal cell naevus syndrome differ from OK?
Histological identical to non-syndromic OK but occur at younger age around 15 years
