OS- Cysts Flashcards
What is a cyst?
A pathological cavity containing fluid/ semi fluid or gaseous contents which is not created by the accumulation of pus.
How can you differentiate between an infected cyst and an abscess?
Because infected cysts lose their cortication they look similar to abscesses so we need to consider the shape/size of the radiolucency.
Cysts will often be round and displace the teeth/bone around them.
Abscesses often have more irregular shapes and don’t displace the surrounding hard tissues. (but they can cause tissue breakdown)
What are the symptoms of a cyst in the jaw?
Pain
Tenderness
Slow growing swelling.
Displacement of teeth.
Mobility of teeth.
Discoloration of the tooth.
Although cysts are often asymptomatic until they get infected.
How can we tell if a cyst comes from the tooth or the periodontium?
Sensibility testing the tooth.
If the cyst comes from the tooth- the tooth will be non-vital.
If the cyst comes from the periodontium- the tooth will be vital.
What initial radiographs do we select to investigate a cyst?
Oblique occlusal/ Periapical / OPT (not for anterior)
What are the radiographic features we look for in a cyst?
- Shape (spherical or egg shaped)
- Margins (defined and corticated unless infected)
- Locularity- often unilocular
- Multiplicity- single/ bilateral (multiple would indicate a syndrome)
- Effect on the surrounding anatomy-
How aggressive is it- Displace (cortical plates/ adjacent teeth/ maxillary sinus/ inferior alveolar canal)
Root resorption? - Inclusion of unerupted teeth in the cyst.
How can we classify cysts?
Structure (epithelial or non epithelially lined)
Pathogenesis (Inflammatory or pathological)
Origin (Odontogenic or non-odontogenic)
What is an odontogenic cyst?
The most common type of bony swelling in the jaw (>90% of bony swellings are odontogenic cysts)
This is an epithelial lined cyst that arises from tooth tissue and is formed in a tooth bearing area.
How do ontogenic cysts form?
From leftover tooth tissue when it is broken down in the jaw.
Rests of mallasez- remnants of hertwigs epithelial sheath (dentine production)
Rests of Seres- remnants of the dental lamina (produces the dental papilla)
Reduced enamel epithelium- remnants of the enamel organ .
What are the two most common types of odontogenic cyst?
Radicular and residual.
What is a radicular cyst?
This is an inflammatory odontogenic cyst that is always associated with a non vital tooth.
What is the presentation of a radicular cyst?
Often asymptomatic (unless infected)
Typically slow growing with limited expansion.
How does a radicular cyst form?
There is proliferation of the epithelial rests of malassez at the apex due to the inflammatory change caused by pulp necrosis:
Either through
- Proliferating epithelium with central necrosis.
- The centre gets cut off from the blood supply & becomes necrotic. (This cyst inside is known as a microcyst which brings fluid into the granuloma)
- The epithelium surrounds the fluid area.
How do periapical granulomas differ from a radicular cyst?
**Peri apical granulomas could be treated by RCT of the tooth, A radicular cyst could not. (Conflicting information) **
Radicular cysts are larger than periapical granulomas. (>15mm diameter then 2/3 of cases would be a radicular cyst)
What are the radiographic features of a radicular cyst ?
- Well defined round/oval radiolucency.
- Corticated margin continuous with the lamina dura of the non-vital tooth.
- Larger lesions may displace the adjacent structures.
- Long standing lesions may cause external root resorption &/ contain dystrophic calcification.
What are the histological features of a radicular cyst?
stratified squamous epithelial lining.
Connective tissue capsule (with inflammation in the capsule)
What is a residual cyst?
When the radicular cyst remains after removal of the tooth or treatment via root canal
What is a lateral reticular cyst?
This is a radicular cyst that is associated with an accessory canal. This is located at the side of the tooth instead of the apex.
What are inflammatory odontogenic cysts?
These are odontogenic cysts associated with a vital tooth.
Give and describe two examples of inflammatory odontogenic cysts?
Radicular (and residual)- cyst occuring at the apex of a non vital tooth.
Paradental cyst- Cysts typically occuring at the distal aspect of a partially erupted mandibular third molar.
Buccal bifurcation cyst- typically occuring at the buccal aspect of the mandibular first molar.
What is a dentigerous cyst?
A cyst associated with the crown of an unerupted (and usually impacted tooth)
(Most common with the 3rd molars in the mandible)
What are the radiographic signs of a dentigerous cyst?
Corticated margins attached to the ADJ of the tooth.
Larger cysts may begin to envelope around the root of the tooth.
Tend to expand symmetrically initially but larger cysts may expand unilaterally.
Discuss the histology of a dentigerous cyst?
Thin non-keratinised Stratified squamous epithelium.
No significant inflammation- BUT may resemble a radicular cyst if inflamed
What do we measure when diagnosing a dentigerous cyst?
And how do we interpret the results?
The radius of the follicle.
If it is >4mm consider that it is a cyst.
If it is >10mm assume it is a dentigerous cyst.
Give an example of a variant of a dentigerous cyst?
An eruption cyst where the cyst is contained in the soft tissues rather than bone. There is enlargement of the follicle around the tooth.
This is more commonin incisors and almost exclusively in children.
What is an odontogenic keratocyst?
This is a cyst that originates from tooth structure but has no specific relationship to the teeth.
How does an odontogenic keratocyst present radiographically ?
It has scalloped margins.
Can be multilocular.
Often causes the displacement of adjacent teeth.
Doesn’t have very good growth pottential.
How do we diagnose an odontogenic keratocyst?
Aspiration biopsy- it should contain squames and has a low soluble protein content.
Discuss the histology of an odontogenic keratocyst.
No rete pegs with the epithelium and connective tissues- this means the epithelium can separate from the wall allowing bits to remain in bone after surgery.
Multicentric growth
Production of daughter cysts (satelite cysts- that can be left behind)
What type of cyst has the biggest problem with recurrence and why?
Odontogenic keratocyst - it has no rete pegs with the epithelium and connective tissue which allows the epithelium to separate from the wall- allowing bits to remain in bone after surgery
What is the presentation of Basal Naevus syndrome?
multiple odontogenic keratocyst
Multiple basal cell carcinomas
Palmar and plantar pitting. .
What is the nasopalatine duct cyst?
A developmental non-odontogenic cyst which arises from the nasopalatine duct remnants.
How does a nasopalatine duct cyst present?
Often asymptomatic-
Patients can note a salty taste in the patient’s mouth without infection.
Larger cysts can displace the teeth or cause swelling in the palate.
Cyst always involves the midline but is not always symmetrical.
Discuss the histology of a nasopalatine duct cyst.
Non-keratinised stratifed squamous with modified respiratory epithelium
How does a Nasopalatine duct cyst present on a radiograph.
Corticated radiolucency between/ over the roots of the central incisors
Often unilocular
May appear Heart shaped- due to the superimposition of the anterior nasal spine.
How do we differentiate between a cyst and the incisive fossa on a radiograph?
If <6mm assume incisive fossa.
6-10mm monitor
>10mm suspect cyst.
What is a solitary bone cyst?
non-odontogenic cyst without an epithelial lining.
e.g. a simple/traumatic or haemorrhagic bone cyst.
How does a solitary bone cyst present?
Usually asymptomatic (incendental finding)
Rarely pain or swelling.
Discuss the radiographic features of a solitary bone cyst?
Most commonly found in the premolar/molar region of the mandible.
Variable definition & cortication.
What is an anerusymal bone cyst?
A cyst in which blood is aspirated during an aspiration biopsy.
What is a Stafne cavity?
This is not a cyst.
This is a depression in the bone which contains salivary or fatty tissue. (although cortical bone is preserved)
It only occurs in the mandible (almost exclusvely lingual.
Discuss the presentation of a stafne cavity.
Often in the angle or posterior body of the mandible.
Well defined & corticated
Inferior to the inferior alveolar canal
Asymptomatic
Rarely displaces adjacent structures.
How do we take an aspiration biopsy.
Using a 5-10ml wide bore needle to drain the contents in the GDP.
How do we take an incisional biopsy?
This is partial removal under LA.
A mucoperiosteal flap is raised with bone removal if required. We incise and remove a section of the lining to obtain a sample.
What is an excisional biopsy?
Complete removal of the cyst.
What are the two cyst treatments. Compare them. Their indications. Advantages and disadvantages.
Enucleation- Removal of the whole cystic lesion under GA.
Indications: Dependent on patient healing ability and adjacent structures.
Advantages- Whole lining can be examined pathologically. Limited closure. Little aftercare needed. Bone healing should happen after removal.
Disadvantages-
Risk of mandibular fracture with large cysts.
Chance of leaving some of the lining (causing recurrence)
If it is a dentigerous cyst we want to preserve the tooth.
Can damage adjacent structures.
Clot filled cavity may become infected.
Contraindications- old age/poor health.
Marsupilisation- Creation of a surgical window in the wall of the cyst to remove the contents and suture it to the surrounding epithelium. To encourage the cyst to decrease in size for later enucleation.
Indications- If enucleation would damage the surrounding structures. If access to the area is difficult. To allow eruption of the teeth affected by a dentigerous cyst. Elderly or medically compromised patients unable to withstand extensive surgery. Very large cysts that would be at risk of jaw fracture with enuclceation.
Advantages- Simple to perform. May spare vital structures. Can combine with enucleation at a later date.
Disadvantages- Opening may close and cyst can reform. Complete lining is not available for histology. It is difficult to keep clean and lots of aftercare needed.
