Cysts of the Jaw & Oral Regions 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 systs?
Inflammatory odontogenic systs
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
Where are epithelial, non-odontogenic cysts found?
Fissures
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
Where are the 3 sources from which the lining of epithelium is derived from?
Rests of Malassez
Reduced enamel epithelium
Remnants of the dental lamina
Which cysts have epithelium derived from the Rests of Malassez?
Radicular cyst
Residual cyst
Which cysts have epithelium derived from reduced enamel epithelium?
Dentigerous cyst
Eruption cyst
Which cysts have epithelium derived from remnants of the dental lamina?
Odontogenic keratocyst
Lateral periodontal cyst
Gingival cyst of adult
Glandular odontogenic 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 are the sources of epithelium of inflammatory cysts and how do they proliferate?
Epithelial cell rests of Malassez derived from remnants of Hertwig’s root sheath
Cell rests dotted throughout PDL, when trapped within periapical granuloma, with correct stimulus it proliferates
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 is the source of epithelium of an odontogenic keratocyst>
Remnants of dental lamina (initial buds before tooth germ, aka Glands of Serres)
What is the source of epithelium of a nasopalatine duct cyst?
Nasopalatine duct epithelium - between 2 palatine processes
What is the source of epithelium of a nasolabial cyst?
Epithelial remnants at site of fissures (between processes)
What is the source of epithelium of a mucous retention cyst?
Salivary duct epithelium
What is the source of epithelium of a lympoepithelial/branchial cyst?
Inclusions of epithelium in lymphoid tissue
What is the source of epithelium of a thyroglossal cyst?
Thyroglossal duct epithelium
What are the stimuli for epithelial proliferation + cavitation?
Inflammation/inflammatory stimulus
Inflammatory cells secrete cytokines
Possible links to genetic defects in a tumour suppressor gene in a subset of odontogenic keratocysts
Genetic stimulus
Give examples where inflammation/inflammatory would be a stimulus for epithelial proliferation + cavitation
Site-specific: e.g. necrotic pulp -> PA granuloma -> inflammatory cyst
Periodontal pocket - lateral periodontal inflammatory dental cyst (if lots of inflammation)
Which cytokines would be released by inflammatory cells for epithelial proliferation + cavitation?
IL-1, IL-6 + TNF + growth factors
Epidermal growth factor (EGF) + transforming growth factor (TGF) beta
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
Describe the epithelial growth method of cystic growth and where do we see it in particular
Growth factors such as EGF + TGF beta may cause pronounced proliferation of cyst epithelium
Particularly important in odontogenic keratocysts which show pronounced mural growth even in absence of marked inflammation
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