2.1 - Intro to Dental Radiology

Question 1

What must we balance in terms of radiographs (3)?

Answer 1

the need for info

radiation dose

diagnostic yield/benefit

Question 2

What are the 3 principles of radiation protection?

Answer 2

Justification

Optimisation

Dose limitation

Question 3

How do we justify if a pt needs a radiograph?

Answer 3

Does the give additional required clinical information that will benefit the pt? or can we dx without

Question 4

What is optimisation?

Answer 4

This is when we consider ALARP - as low as reasonably practicable - this means that the dose we give to the pt is as low as it can be taking into account potential constraints such as What

Question 5

What is dose limitation for?

Answer 5

Workers and general public - not the pt

Question 6

What 3 things do we need to produce a radiographic image?

Answer 6

SOURCE OF X-RAY

OBJECT - TEETH AND JAWS

IMAGE RECEPTOR (can be digital or film)

Question 7

What is a latent image?

Answer 7

One that is not yet visible and must be converted to permanent image via computer or film using chemicals

Question 8

What is processing?

Answer 8

This is where we convert latent image to permanent visible image via digital or chemical means

Question 9

What electricity supply do x-ray machines use?

Answer 9

60-70kV

Question 10

What are some properties of x-rays? (4)

Answer 10

X-rays are ELECROMAGNETIC RADIATION

They travel as a straight diverging beam

photographic

interacts with matter

Question 11

What is the inverse square law?

Answer 11

This is where x-ray beam is inversely proportion to the square distance from the source - so if we stand back from source of radiation by 1/2 it quarters the dose to radiologist

if we stand back 1/4 it will 1/8th the dose

Question 12

What happens if x-rays have no effect?

Answer 12

This means x-ray beams pass straight through with no interaction (ie through air) and image appears black

Question 13

What happens if x-rays are completely absorbed?

Answer 13

the material completely absorbs the photons and as a result appear white

Question 14

What happens when x-rays are absorbed and scattered?

Answer 14

This is when there is partial absorption of the x-ray beam but individual components have had a directional change and can exit the pt

Question 15

What is a radiographic image a record of?

Answer 15

The pattern of attenuation of the x-ray beam after it has passed through matter

Question 16

What types of dental radiographic views do we have?

Answer 16

Bitewings

PAs

Occlusal

Panoramic

Cephalometric

Question 17

What are bitewings used for?

Answer 17

To show the U+L pre molars and molars (ideal BW goes from medial of 8 to distal of 4) and should show symmetry of upper and lower teeth with minimal overlap of adjacent teeth (to allow for detection of caries)

Question 18

What will the ideal bitewing show? (6)

Answer 18

• upper and lower crowns of one side
• medial first pre molar to most distal contact point or surface
• no to minimal overlap of teeth
• enamel dentine junction
• coronal pulp morphology
• ID bone unless lots of bone loss

Question 19

What can bitewings detect? (5)

Answer 19

IP caries

cervicle caries

O,B,L caries

restorations - ledges and defects

ID bone changes over time

Question 20

What are PAs?

Answer 20

These are used to show the full length of at least one tooth and bone levels

Question 21

If we are doing an XLa what must we see in radiograph?

Answer 21

roots

surrounding bone

canal

Question 22

What can PAs detect?

Answer 22

crown - caries, trauma and nc tooth surface loss

change to restos

pulpal pathology

root morphology

surrounding bone levels

Question 23

What are occlusal radiographs?

Answer 23

An occlusal radiograph is a radiograph designed to be placed between the occlusal surfaces of the teeth with the central beam directed at 90o or at 50 -60o to the plane of the film depending on what is required to be viewed.

Question 24

What extra-oral radiographs can we take?

Answer 24

OPT - good for ortho tx planning and showing impacted wisdom teeth

Lateral cephalometric - used to view facial bones and analyse skeletal and dental relationships and look at soft tissue profile