CBCT Interpretation

Question 1

What is a good system of examination for CBCTs?

Answer 1

-symmetry
-margins
-bone consistency
-dentition
-supporting bone
-any other features?
-summary
-proposals

Question 2

When looking at symmetry and margins, what can you see here?

Answer 2

-superimposition of petrous temporal bone
-cloudy left sinus
-straight upper margin
-defined/cortication??

Question 3

When you see a feature and you don’t know what it is, how should you describe it?

Answer 3

-radiolucent/radiopaque
-site, shape, size
-margins
-other structures (Aetiology? and effect)
-provisional/differential diagnosis

Question 4

What are the definitions of radiolucent/radiopaque?

Answer 4

Radiolucent = loss of previously opaque material (bone, teeth -caries/cystic lesions)

Radiopaque = increased attenuation of x-ray beam (natural tissues don’t fully attenuate)

Question 5

What can cause radiopaque areas?

Answer 5

-increased density e.g. cortical bone
-increased thickness e.g. overlaps of teeth
-alteration e.g. soft tissue calcification
-soft tissue within an airspace

Question 6

Examples of ways to describe the site of a lesion?

Answer 6

-teeth
-alveolus
-basal bone (non-odontogenic)
-other bones
-extra-osseous

Question 7

What are the different ways in which you can describe the shape of a lesion?

Answer 7

-circular/oval
-unilocular (one obvious lesion, simple shape)
-multiocular (scalloped margin or internal divisions)
-irregular

Question 8

Why are we interested in the size of unknown lesions?

Answer 8

May indicate length of time its been tehre

Question 9

Why are we interested in the size of unknown lesions?

Answer 9

May indicate length of time its been there

Question 10

How do you describe the margins of a lesion?

Answer 10

-Well defined: corticated or not corticated
-Ill-defined

Question 11

When thinking about the aetiological relationship about an unknown lesion, what do you consider?

Answer 11

-apex of a tooth - ? vital
-crown of a tooth

is it related to a tooth or not basically

Question 12

What effects might a lesion have on other structures?

Answer 12

-no effect (lesions might not be big enough to have an impact)
-displacement (remodelling of bone etc)
-expansion
-resorption

Question 13

For provisional/differential diagnosis, what is a radiological sieve that you can go through?

Answer 13

-normal
-developmental
-traumatic
-inflammatory
-cystic
-neoplastic
-osteodystrophy
-metabolic/systemic
-idiopathic
-iatrogenic (cause by health professional)
-foreign body
-artefact

Question 14

What is the difference between CT and CBCT?

Answer 14

CT has hard and soft tissues
CBCT - only hard tissues (was developed for maxillodental features)

CBCT has a lower radiation dose. Is a beam rather than a thin fan

Question 15

What are the clinical indications for CBCT in dentistry?

Answer 15

-implant planning
-impacted teeth (normal and supernumeraries)
-pathology (cystic lesions, infections, benign tumours)
-orthognathic surgery
-hypodontia (implant planning)
-cleft palate for bone defects
-dental abnormalities - dilaceration, double teeth
-endodontic problems
-autotransplantation

Question 16

What guidance is there surrounding CBCT in dentistry?

Answer 16

-Sedentexct Guidelines on CBCT for Dental and Maxillofacial Radiology (2011)
-Guidance on safe use of dental cone beam CT equipment (2010) - government

Question 17

There are 20 EADMFR basic principles on the use of CBCT. What are some of them?

Answer 17

-use only when the Q cannot be answered adequately with a lower dose method
-if evaluation of soft tissues is required use medical CT or MRI
-use smallest volume compatible with clinical situation
-choose resolution compatible with situation (dont use higher resolution if not required)

Question 18

What are the different segment views you get with CBCT?

Answer 18

-axial
-coronal
-sagittal (from side)