Radiographic Interpretation and CBCT

Question 1

What details are useful to include when reporting on periradicular changes?

Answer 1

Location

Size

Margins

What these changes signify

If appropriate suggest further investigation or treatment

Question 2

What are the steps in the system of examination for EO radiographic images?

Answer 2

symmetry
margins
bone consistency
dentition
supporting bone
any other features

-> summary/proposals

Question 3

What are the stages in visual analysis of EO radiographic images?

Answer 3

If you can see right and left- compare and look for differences
 Start at the top and go down
 Look for unusual opacities and radiolucencies
 Look for site (how is it related to other structures- does it affect/relate to aetiology), size (can be misleading), shape

Question 4

What does a straight horizontal upper margin slightly curved at the sides suggest?

Answer 4

Presence of a liquid/fluid (meniscus)

Question 5

What does a curved upper margin suggest radiographically?

Answer 5

Something expanding

Question 6

What does radiolucency suggest? In which cases would it be seen?

Answer 6

Loss of hard tissue
-> Seen in bone and teeth OR Cysts

Question 7

What causes structures to appear radiopaque?

Answer 7

Increased attenuation

Question 8

What are the causes of increased attenuation?

Answer 8

Increased density e.g. cortical bone

Increased thickness e.g. overlaps

Changes/Alteration of tissues e.g. soft tissue calcification

Soft tissue within an air space

Amalgam and gold restorations

Question 9

What are the different descriptors for shape when interpreting radiographs?

Answer 9

 Circular- expanding evenly
 Unilocular- one obvious lesion, simple
 Multilocular- scalloped margin, internal divisions
 Irregular- difficult to describe (more worrisome- esp. if irregular borders)

Question 10

What may size of a radiographic lesion indicate?

Answer 10

Length of time it has been present (not always)

Question 11

What are the different descriptors for margins of radiographic lesions?

Answer 11

Well defined:
Corticated (white line)
Non-corticated

Ill-defined (require investigation)

Question 12

Why are corticated lesions preferred?

Answer 12

Slow progressing as bone remodelling required

Question 13

What are the different effects a lesion seen on a radiograph can have on other structures?

Answer 13

no effect

displacement

expansion

resorption (aggressive)

Question 14

What are the options in the radiological sieve used in making provisional diagnosis?

Answer 14

normal
developmental
traumatic
inflammatory
cystic
neoplastic
osteodystrophy
metabolic/systemic
idiopathic
iatrogenic- caused by tx
foreign body
artefact- broken digital receptor

Question 15

What are unerupted teeth surrounded by?

Answer 15

Reduced enamel epithelium

-> Can undergo pathological change

Question 16

What happens if you remove a tooth that has a cyst but not the cyst itself?

Answer 16

It can remain and grow
-> if assymptomatic monitor radiographically every 6-12 months

Question 17

What can happen to corticated lesions due to infection?

Answer 17

Loss of corticated margin

Question 18

What is the issue with the antral septum

Answer 18

Can create illusion of pathological lesion from some views

Question 19

What are the features of conventional CT?

Answer 19

Thin fan shaped beam directed at patient on table
 Detectors pick up the beam as it goes around patient many times
 Creates axial slices- modern machines can look at sagittal and coronal
 Very high x-ray dose
 Shows hard and soft tissues

Question 20

What are the features of CBCT?

Answer 20

Beam is cone shaped, requires bigger detector to pick up beam
 Will typically go around patient once (single rotation)
 Less radiation
 Better for hard tissues

Question 21

What are the indications for using CBCT?

Answer 21

Implant planning

Impacted teeth (normal and supernumeraries)

Location

Relations, e.g. inferior alveolar canal, root resorption

Pathology – cystic lesions, infections,

Question 22

Indications for CBCT continued:

Answer 22

Benign tumours

Orthognathic surgery

Hypodontia

Cleft palate – bone defects

Dental abnormalities – dilaceration, double teeth

Endodontic problems

Autotransplantation

Question 23

In what situations in CBCT not used?

Answer 23

Cancer patients

Question 24

What are some of the most important principles when using CBCT?

Answer 24

Use only when question cannot be answered adequately with lower dose method

If evaluation of soft tissues required- consider Medical CT or MRI

Use smallest volume compatible with clinical situation

Choose lowest resolution compatible with equipment (lowers dose)