Odontogenic cysts Flashcards
What is a cyst?
- A pathological cavity containing fluid or gas.
- Not created by the accumulation of pus.
- Most are lined by epithelium (but not all)
- The site of origin is often obvious.
In the jaws all odontogenic cysts are ________, but a number of cystic lesions, which included in the differential diagnosis, are not. They are derived from epithelial residues of tooth forming organ.
epithelium lined
What problems do cysts cause?
- Increase in size
- Damage or displacement of teeth
- Vital structures damaged (e.g. IAN compression injury)
- Infection
- Pain
- Bone resorption – pathological fractures e.g. with chewing
Cysts are common, and there are several classifications used to describe them which overlap with each other. List the classification of odontogenic cysts.
Odontogenic cysts of inflammatory origin:
* Radicular cyst (70%)
* Residual cyst
Inflammatory collateral cysts
* Paradental cyst
* Mandibular buccal bifurcation cyst
Odontogenic & non- odontogenic developmental cysts: (non inflammatory)
* Dentigerous cyst (15%)
* Eruption cyst
* Odontogenic keratocyst (10%)
* Lateral periodontal cyst (5%)
* Botryoid odontogenic cyst
* Gingival cysts(5%)
* gingival cysts of adults
* gingival cysts of infants (alveolar cyst)
* Glandular odontogenic cyst (5%)
* Calcifying odontogenic cyst (5%)
* Orthokeratinised odontogenic cyst (5%)
Which cells do odontogenic cysts develop from?
o Epithelial rests of Serres
o Reduced enamel epithelium
o Rests of malassez
Give examples of cystic lesions that are not epithelium lined.
E.g., solitary bone cyst, aneurysmal bone cyst which may be included in a classification as ‘bone cysts’.
Generally, cysts whereby the epithelial lining is derived from remnants of the tooth forming tissue are formed odontogenic, and further subdivided into ____________ and _________ cysts.
Inflammatory and developmental
What are cysts whose epithelial lining is derived from sources other than tooth forming tissues classified as?
Non-odontogenic. (developmental)
What are the incidence of cysts?
90% odontogenic
10% non odontogenic
Describe the mechanism of Cystic growth.
Need source of epithelium, stimulus for epithelial proliferation and mechanism of growth & bone resorption:
- Inflammation causes epithelium proliferation and the cells in the cyst centrally breakdown. Increased osmotic pressure thereby draws the water inwards.
- Bone resorption occurs due to the release of collagenase and prostaglandins by fibroblasts, osteoclasts and stimulating factors.
- Initially bony hard swelling forms, which becomes thinner and you get egg shell like crackling, which can then become a fluctuant swelling.
What are the key features of a cyst?
- Form sharply defined radiolucency’s (>20mm more likely to be cyst) – round or ovoid shape, surrounded by a narrow, radiopaque or corticated margin and extends to lamina dura of involved tooth. (MUST consider keratocyst as differential diagnosis)
- Fluid may be aspirated, and some thin-walled cysts can be transilluminated (difficult intra-orally)
- Slow growing, displace rather than resorb teeth
- Symptomless unless infected and often incidental findings on radiographs – important not to leave as can lead to infection, displacement of local structures like teeth / neurological structures.
- If symptomatic: can cause movement of teeth, discreet swelling, infection, pain
- Rarely large enough to cause pathological fractures if bone resorption occurs.
- Form compressible and fluctuant swellings if extending into the soft tissues
- Appear bluish when close to the mucosal surface
What is a radicular cyst?
- Most common of all odontogenic cysts, account for over 50% of jaw cysts
- Usually found at apex of tooth – arise due to proliferation of epithelial remnants of PDL as a result of periapical periodontitis due to death of pulp.
- Usually asymptomatic – incidental finding on rads – well defined, corticated radiolucency. Usually unilocular but can be multilocular always associated with non-vital tooth
- Long term: can cause swelling, bony expansion.
- Rarely occur before 10 years of age usually 30-50 yrs of age. More common in males
How does a radicular cyst grow?
- Due to chronic inflammation in the peri-radicular tissues resulting in a periapical granuloma stimulating the epithelium rests of Malassez.
- Following this there is central degeneration and necrosis which causes the formation of a cavity (lined by epithelium).
- Cyst expansion occurs via hydrostatic pressure as debris accumulates centrally.
- Radicular cysts are always associated with a non-vital tooth, and this is important diagnostically. May get infection.
- More common in maxilla (highest in anterior region)
What is the treatment for radicular cyst?
Enucleation – soft tissue over the cyst is lifted, and cyst removed/nucleated – cystic capsule completely removed reducing possibility of recurrence. Remaining cavity thoroughly cleaned & tight closure completed.
What is a residual cyst?
- These are radicular cysts which remain in situ after the tooth/teeth have been removed.
- Although the histological features are very similar, the source of the inflammation has been removed therefore the wall of a residual cyst may mature and become relatively uninflamed with a thin and irregular lining.
