Cysts Flashcards
What is a cyst?
Pathological cavity containing fluid, semi-fluid or gas
Often lined by epithelium
What can the classification of a cyst be based on?
Location (jaw/soft tissues/maxillary antrum)
Cell type (epithelial/non-epithelial)
Pathogenesis (Developmental/inflammatory)
What are the 2 main categories of cysts based on WHO (1992)?
Epithelial
Non-epithelial
What are the 2 types of epithelial cysts?
Odontogenic & non-odontogenic
What are the 2 types of odontogenic cysts?
Inflammatory odontogenic cysts
Developmental odontogenic cysts
What are the 3 types of inflammatory odontogenic cysts?
Radicular cyst (apical & lateral)
Paradental cyst
Residual cyst
What are the 5 types of developmental odontogenic cysts?
Odontogenic keratocyst
Dentigerous cyst (Follicular/eruption cyst)
Lateral periodontal cyst
Glandular odontogenic cyst (sialo-odontogenic)
Gingival cyst of adults
Name 3 types of epithelial, non-odontogenic cysts
Median palatine cyst
Nasiolabial cyst
Nasopalatine cyst (incisive canal cyst)
Are non-epithelial cysts odontogenic or non-odontogenic?
Non-odontogenic
Name 2 types of non-epithelial cysts
Solitary bone cyst
Aneurysmal bone cyst
What are the 3 things needed for a cyst to form? (Pathogenesis)
- Source of epithelium
- Stimulus for cavitation + epithelial cell proliferation
- Mechanism(s) for continued cyst growth + accompanying bone resorption (cyst will only grow if bone is resorbed)
What is the source of epithelium of dentigerous cysts and how does it proliferate?
Reduced enamel epithelium (REE)
Space between REE + enamel leads to cyst formation
What are the 3 mechanisms of cyst growth?
- Internal hydraulic pressure
- Bone resorption
- Epithelial growth
Describe the internal hydraulic pressure mechanism of cystic growth and which cysts it occurs in
Expansion of inflammatory + dentigerous cysts
Protein accumulation within cyst walls as semipermeable membrane due to osmotic pressure
Fluid accumulates within cyst lumen creating positive pressure in the cysts -> encouraging bone resorption
Describe the bone resorption method of cystic growth
Pro-inflammatory cytokines IL-1 (released by macrophages), TNF + PGER (released by fibroblasts) induce bone resorption
Produced by inflammatory cells in cysts, stimulating bone resorption
What are the general clinical features of cysts?
Swelling
Displacement/loosening of teeth
Pain (if infected)
Eggshell cracking
Sign of fluctuance - movable/compressible; the larger the cycts, the more fluctuance
What type of radiograph would you take for small cystic lesions?
I/O PA
How many rads are usually taken for cysts? How are they taken and why?
2 images taken at right angles to each other
So can locate where the cyst is
Which radiographs are taken of the maxilla?
PA + oblique occlusal
OPG + lateral oblique
Occipitomental (OM)
True lateral
CBCT
Which radiographs are taken of the mandible?
PA + true occlusal
OPG + lateral oblique
PA (Ap) of mandible
CBCT
What are the radiological signs to look for?
Location
Size
Shape
Margin
Effect on adjacent structures
How do cysts appear clinically?
Well-defined, round or oval radiolucency
Well-defined margin
What type of teeth are radicular cysts related to?
Related to non-vital tooth
Where do radicular cysts develop within?
Periapical granuloma
Describe how a radicular cyst would look on a radiograph
Unilocular, well defined, well corticated radiolucency at apex of non-vital tooth
Where is the commonest site of radicular cysts?
Upper incisors
What are the peak ages for a radicular cyst?
4-5th decade
Describe the nature of radicular cysts’ growth
Regular growth limited buccal expansion
Usually continuous with the lamina dura of root of affected tooth
Do radicular cysts cause resorption?
Do not usually cause resorption
If long-standing can cause resorption + displacement of adjacent teeth
How are radicular cysts treated?
Endo
surgical extraction
What can form if a radicular cyst is retained following an extraction?
Residual radicular cyst
Describe what a residual radicular cyst looks like on a radiograph
Well-defined, round/oval radiolucency
Where are residual radicular cysts always found?
Edentulous area
After extraction of affected tooth
What is the key histology of a radicular cyst?
Thick wall of fibrous granulation tissue
Inflamed - chronic + acute inflammatory cells (neutrophils)
Cholestrol clefts + foreign body giant cells in wall/lumen
Mucous cells particularly in maxillary cysts, due to location - hyaline bodies may be seen
Describe the epithelial lining of a radicular cyst
Non-keratinised stratified squamous
Variable thickness most common but can be thin/attenuated in long-standing cysts
What is inside the lumen of a radicular cyst?
Pale pink serous exudate, macrophages, desquamated epithelial cells, inflammatory cells + cholestrol clefts
What are dentigerous cysts also known as?
Eruption cysts
What are dentigerous cysts attached to?
Attached at CEJ surrounding crown of unerupted 8s + 3s (typically enveloping crown)
What is the peak age for a dentigerous cyst?
3-4th decade
When is a cyst expected in regard to the follicular space?
If it exceeds 3mm
Describe the radiological appearance of a dentigerous cyst
Unilocular, well-corticated radiolucency, late buccal expansion
Classically crown of associated tooth lies centrally within cyst