Cysts Flashcards
Define: cyst
Pathological cavity (usually epithelial lined) containing fluid, semi-fluid or gas that is not produced by the accumulation of pus
Describe the lining of cysts
- Continuous epithelial lining
- Discontinuous epithelial lining
- No epithelial lining
How do the majority of odontogenic cysts grow? What is the significance?
Hydrostatic mechanisms
Results in the round shape
How do OKC grow?
Through the medullary bone
What is required for a cyst to grow?
- Source of epithelium
- Proliferative stimulus
- Mechanism for growth
Define: odontogenic cyst
Cyst lined by epithelium dervied from odontogenic epithelium
Define: non-odontogenic cyst
Cyst lined by epithelium that is non-odontogenic in origin
Define: Inflammatory cyst
Inflammation is the stimulus causing epithelial proliferation and cyst formation
Define: developmental cyst
Where aetiology is unknown and deemed developmental
Epithelial source for radicular and residual cysts
Cell rests of Malassez
Epithelial source for dentigerous cysts and eruption cysts
Reduced enamel epithelium
Epithelial source for OKC, lateral periodontal cyst
Cell rests of Serres (remnants of the dental lamina)
List the odontogenic developmental cysts
OKC Dentigerous cyst Lateral periodontal cyst Eruption cyst Glandular odontogenic cyst Gingival cyst
List the odontogenic inflammatory cysts
Radicular cyst
Residual cyst
Paradental cyst
Which cysts are non-odontogenic?
Nasopalatine
Nasolabial
Presentation of cysts
- Compressible swelling if large
- Displacement or loose teeth
- If infected - similar symptoms to abscess (pain, discharge)
How does swelling occur with cysts?
Cyst expands through the normal anatomical boundaries of bone
Where is the swelling of cysts usually located?
Buccal or palatal in maxilla
Buccal in mandible (rare in lingual as it is thicker than buccal)
What are the characteristic clinical signs of cysts
- Eggshell cracking
- Bluish colour of mucosa
- Fluctuation
- Discharge of colourless fluid (cholesterol crystals)
What is eggshell cracking? How does it occur?
Continued resorption and bony expansion results in a thin layer of bone around the cyst which is easily broken on palpation
What is fluctuation?
Pushing the swelling on one side and feeling the transmission of pressure on the other side
What does fluctuation indicate?
The lesion is fluid filled
What proportion of patients with cysts have no symptoms
1/3 are asymptomatic and found by chance on radiograph
How may a cyst be detected during rct?
Inability to dry canals with paper points, could be due to cholesterol clefts indicating a cyst
List the investigations for cysts
Vitality testing of nearby teeth
Radiographs
Biopsies to confirm diagnosis
Aspiration?
List the histological features of INFLAMMATORY cysts
- Non-keratinised stratified epithelial lining
- Thick fibrous wall
- Inflammation markers present
- Cholesterol clefts
- Hyaline bodies
How do cysts resorb bone?
- The cyst itself does not resorb, instead the cyst/inflammatory mediators induces osteoclast activation
How fast do cysts grow on average?
Slow - 2cm in 10 years
How fast do cysts grow in children and why?
Faster - 5cm in 2 years
Due to less dense bone and quicker turnover
Frequency of radicular cysts
70%
Frequency of dentigerous cysts
15-20%
Frequency of OKC
3-5%
Define radicular cyst
Inflammatory cyst that develops from cell rest of Malassez stimulated to proliferate via inflammatory process arising from pulpal necrosis
Describe the lining of radicular cysts
Non-keratinised, squamous epithelium
May be discontinuous if replaced by granulation tissue or mural cholesterol nodules
What histological features are associated with radicular cysts
- Acute and chronic inflammatory cells
- Cholesterol clefts
- Foamy macrophages
- Hemosiderin
- Rushton’s bodies
Where are radicular cysts commonly found
Apex of non-vital tooth
Upper laterals common
Anterior maxilla > mandible
Describe the radiographic appearance of radicular cysts
- Size - 1.5-3cm dia
- Shape - round, unilocular
- Outline - smooth, well corticated if long standing and may be continous with lamina dura
- Uniformy radiolucent
What effects do radicular cysts and residual cysts have on adjacent structures
Displaced adjacent teeth (Rarely resorbed)
Buccal expansion
Displacement of antrum
Difference between the radiographic appearance of radicular cysts and apical granuloma
- Cysts have corticated margins, whereas granuloma does not
Define a residual radicular cyst
Remnant of a radicular cyst after the causative tooth has been extracted
How do residual cysts grow?
Via osmotic pressure - however it is very low as the tooth is not there
Where are residual cysts found?
Apical regions of an edentulous area in a tooth bearing region
Usually mandibular premolar area
Describe radiographic appearance of residual cysts
- Size - 2-3mm dia
- Shape - round, unilocular
- Outline - smooth, well-defined and well corticated margins
- Uniformly radiolucent
Define dentigerous cysts
Cyst developing from the remnants of the reduced enamel epithelium after the tooth has formed
What features does a cyst need in order to be dentigerous?
- Must contain the crown of the unerupted tooth
- Epithelial lining of the cyst is attached to the CEJ of the unerupted tooth