Radiological interpretation and the differential diagnosis of radiolucencies of the jaws Flashcards
What thought process should you follow when you see a radiolucency on a radiograph?
What do the submandibular fossa look like on a radiograph?
What does unilocular mean?
having, consisting of, or characterized by only one loculus or cavity; single-chambered.
What are the different types of cyst?
- Odontogenic cysts (formed from tissues involved in odontogenesis):
- radicular dental cyst
- residual dental cyst
- lateral periodontal cyst
- dentigerous cyst - Non-odontogenic cysts:
- nasopalatine duct cyst
- bone cysts (solitary bone cysts, aneurysmal bone cyst)
- nasolabial cyst
What is a radicular cyst?
- Origin: Cell rests of Malassez from the epithelial remnants of Hertwig’s root sheath.
- Most commonly found in adults aged 2-50.
- Most common of all jaw cysts (>70%)
- Site: Apex of a non-vital tooth
- Size: 1.5 – 3cm
- Shape: Round / Oval and unilocular
- Outline: Smooth, well defined, corticated (unless infected whereby cortication is lost)
- Radiodensity: Uniformly radiolucent
- Effects: Displace teeth, antral floor, IDN canal. Buccal expansion. Can resorb teeth but rarely
What’s the difference between a chronic and an acutely developed cyst?
See image
What is a residual cyst?
- Origin: Refers to a radicular cyst remaining after the causative tooth has been removed
- Age: Commonly adults >20 years
- Site: Apical region of the tooth bearing portion of the jaws
- Size: 1.5 – 3cm
- Shape: Round / Oval and unilocular
- Outline: Smooth, well defined, corticated (unless infected whereby cortication is lost)
- Radidensity: Uniformly radiolucent
- Effects: Displace teeth, antral floor, IDN canal. Buccal expansion. Can resorb teeth but rarely
What is a lateral periodontal cyst? (developmental)
- Origin: ? Reduced enamel epithelium
- Age: Commonly adults >30 years
- Frequency: Rare
- Site: Lateral root surface
- Size: Small
- Shape: Round and unilocular
- Outline: Smooth, well defined, corticated (unless infected whereby cortication is lost)
- Radiodensity: Uniformly radiolucent
- Effects: Displace teeth if large, rarely resorb. May cause buccal expansion
What is a botyroid cyst?
A multilocular variant of a lateral periodontal cyst. It is rare and seen more in middle age to older adults.
What is a dentigerous (follicular) cyst?
- Origin: Remnants of the reduced enamel epithelium after tooth formation
- Age: Usually adolescents / young adults
- Frequency: ~20% of odontogenic cysts
- Site: Crown of an unerupted and displaced tooth (3’s and 8’s)
- Size: Suspected if follicle >3-4mm can become large (several cm’s)
- Shape: Round / oval and unilocular
- Outline: Smooth, well defined, corticated
- Radiodensity: Uniformly radiolucent
- Effects: Displace teeth and resorb in ~50% May cause bony expansion displacement of the antrum
What is an eruption cyst?
a bluish swelling that occurs on the soft tissue over an erupting tooth. It is usually found in children. The fluid in thecyst is sometimes clear creating a pale-coloured cyst although often they are blue. An eruption cyst (eruption hematoma) is a developmental soft-tissue cyst ofodontogenic origin that forms over an erupting tooth.
What’s a nasopalatine duct cyst? (incisive canal cyst)
- Origin: Epithelial remnants of the nasopalatine duct or incisive canal.
- Age: Variable but commonly middle aged
- Frequency: Most common non odontogenic cyst ~1% of population
- Site: Midline anterior maxilla
- Size: From 6mm to several cm’s
- Shape: Round / oval and unilocular
- Outline: Smooth, well defined, corticated
- Radiodensity: Uniformly radiolucent
- Effects: Displace teeth distally, rarely resorb. Palatal expansion
What is a solitary bone cyst?
Commonly seen in the young – probable trauma related
What are the different types of multilocular radiolucencies seen in radiographs of the head and neck?
1. Odontogenic tumours:
- Keratocystic odontogenic tumour (Odontogenic keratocyst)
- Ameloblastoma
- Ameloblastic fibroma Ameloblastic fibro- odontoma
- Odontogenic myxoma
- Odontogenic fibroma
- Sialo-odontogenic tumour
2. Giant cell lesions:
- Central giant cell granuloma
- Cherubism
- Browns Tumour of Hyperparathyroidism
- Aneurysmal bone cyst
What is an odontogenic keratocyst?
- A multilocular radiolucency.
- They are seen in Gorlin Goltz Syndrome.
- Origin: Epithelium of the dental lamina
- Age: Peak incidence 2nd to 3rd decade
- Frequency: Rare but most common (if termed an odontogenic tumour)
- Site: Posterior body / angle of mandible Anterior maxilla canine region
- Size: Variable
- Shape: Oval, extending along the body of the mandible Pseudo / multilocular
- Outline: Smooth and scalloped, well defined and corticated
- Radiodensity: Uniformly radiolucent
- Effects: Tooth displacement, rarely resorb. Extensive expansion within cancellous bone. Possible cortical perforation.