L7 Introduction to interpretation of radiolucencies Flashcards
What 3 categories are dental radiolucencies divided into?
- Normal anatomical structure
- Artefact
- Pathology (congenital, developmental, acquired)
Describe some artefactual radiolucencies you may see in practice.
- Cracked sensor (creates radiolucent shadow)
- Blooming, seen in early solid state decetors
- Radiolucent line due to a bend in film
- Finger nail bends on film
- Film fogging due to light exposure prior to processing
When describing a pathological radiolucency, what factors need to be included?
- Site or anatomical position
- Size
- Shape
- Outline/edge of periphery
- Relative radiodensity
- Effects on adjacent structures
- Rate of growth (of previous radiographs are available to compare to)
Name some acquired causes of a pathological radiolucency.
- Localised infection
- Spreading infection
- Trauma
- Cyst (odontogenic or non)
- Tumour (odontogenic or non)
- Allied lesion (giant cell lesion, bone cyst, fibro-osseus lesion etc.)
Why is the position of a radiolucency relative to the ID canal important to note?
- Radiolucencies above the ID canal are likely to be odontogenic in origin
- Radiolucencies below the ID canal are likely to be non-odontogenic in origin, more likely vascular or neural origin
Name 3 lesions which are absolutely site specific.
- Radicular cyst: always at the apex of a non-vital tooth
- Dentigerous cyst: always found surrounding crown of unerupted tooth
- Nasopalatine duct cyst: always symmetrical around the midline of the maxilla
Why is the size of a radiolucency important?
Size can help to differentiate a lesion from normal anatomy, or can be helpful to differentiate between types of lesions.
What is the size of a normal follicle present around a developing tooth compared to a dentigerous cyst surrounding an unerupted tooth?
- Normal follicle size is 3mm or smaller (vertical measurement)
- Radiolucency greater than 3mm is more likely to be cystic
What is the normal size of the nasopalatine foramen compared to a nasopalatine duct cyst?
- Nasopalatine foramen = smaller than 6mm
- Cyst = greater than 6mm
NB: horizontal measurement
Compare the size of a periapical granuloma versus a radicular cyst (horizontal measurement).
- Periapical granuloma: likely to be less than 15mm
- Radicular cyst: likely to be greater than 15mm
Give 6 descriptions of radiolucency shapes.
- Monolocular (unilocular)
- Multilocular (e.g. ameloblastoma)
- Pseudolocular
- Round
- Oval
- Irregular (e.g. a simple bone cyst)
Name lesions that are commonly multilocular.
- Odontogenic keratocyst
- Botryoid odontogenic cyst
- Ameloblastoma
- Ameloblastic fibroma
- Odontogenic myxoma
- Giant cell lesion: central giant cell granuloma, cherubism, Brown tumour
- Aneurysmal bone cyst
Describe the outline of a residual cyst.
Well defined and corticated margin.
Clearly differentiated boundary between the lesion and normal bone.
Describe the outline of a nasopalatine duct cyst.
Well defined and corticated margin.
Well defined and corticated margins are usually seen in what type of disease?
Slow growing, benign disease. (Grows slow enough to be corticated).
- Cysts
- Benign odontogenic tumours
- Giant cell lesions
What does this image show?
A cementoblastoma.
Radiopaque.
Descibe the relative radiodensity of an odontoma.
Predominantly radiopaque lesion surrounded by a radiolucent margin.
Which lesions cause expansion of adjacent structures?
Slow growing, benign lesions.
E.g. giant cell lesion displacing the teeth.
Which lesion type appears ill-defined and “moth eaten”, and can cause the appearance of “floating teeth”.
Malignant lesion
Summary of radiolucencies.
