Radiographic Localisation

Question 1

Function of radiographic localisation

Answer 1

To determine location of a structure or pathological lesion in relation to other structures

Question 2

When is there a need for radiographic localisation?

Answer 2

Where clinical examination is insufficient to provide an answer

Question 3

What clinical situations would lead to a radiograph localisation being taken? (5)

Answer 3

1. Position of unerupted teeth
   - Normal but impacted/ectopic
   - Supernumerary
2. Location of roots/root canals
   - Endo
3. Relationship to pathological lesions
4. Trauma
   - Dental
   - Bone fractures
5. Soft tissue swellings
   - Tissue/source

Question 4

What do you see from the OBSERVATION radiograph 36?

Answer 4

36

• Radiolucency on mesial apex
• Indicates tooth is non vital due to periodical periodontitis
• Needs RCT if to be saved

Question 5

Why is the distal root on the 36 shorter than the mesial?

Answer 5

• In this situation we know theres a periapical radiolucency related to the mesial root
• Due to chronic inflammatory changes we got some resorption of that root

Question 6

What do you see from the OBSERVATION radiograph 38?

Answer 6

• Mesial root curved distally
• Dilaceration (sharp end between coronal and apical part)
• Significant if this was tooth to be extracted
• 8 NOT

Question 7

What do you see from the OBSERVATION radiograph supernumerary?

Answer 7

• Distal to 3rd molar
• Positioned transverse to the arch, we are seeing it end on (cross sectional) so we don’t know whether the crown is lingual or buccal

Question 8

What caused the white strip in the OBSERVATION radiograph?

Answer 8

• White strip in image - caused by rectangular colonator

- Xray tubehead was too high up

Question 9

Is the OBSERVATION radiograph acceptable?

Answer 9

Depends on what tooth it was taken for

36

• Bit missing mesially
• Takes it down to a good

38
- Good can see all bony features around

Question 10

Options for views at right angles

Answer 10

1. Panoramic + lower true occlusal
2. Paralleling periapical + lower true occlusal
3. CBCT (cone beam CT)

Question 11

Define parallax

Answer 11

An change in the position of an object caused by a change in the position of the observer

Question 12

Parallax mnemonic

Answer 12

Same
Lingual
Opposite
Buccal

Question 13

Reasoning behind the parallax mnemonic

Answer 13

If the object we are interested in moves the same direction as the Xray tube source is lingual

If it moves in the opposite direction its buccal

Question 14

What is a mesiodens?

Answer 14

Supernumerary tooth present between 2 central incisors

- Usually results in malocclusion, food impaction, poor aesthetics + cyst formation

Question 15

Radiopaque/radiodense on a radiograph

Answer 15

White

Question 16

Radiolucent on a radiograph

Answer 16

Black