Extra Oral radiographs

Question 1

Types of extra-oral radiographs

Answer 1

• panoramic
• lateral and postero-anterior cephalograms
• oblique lateral radiographs
• skull radiographs

Question 2

define cephalometry

Answer 2

the measurement and study of the head

Question 3

orthodontic use cases for lateral cephalograms

Answer 3

• assessing skeletal discrepancy when functional appliances are to be used for labio-lingual movement of incisors
• Locating and assessing unerupted, malformed or misplaced teeth

Question 4

Extra-oral radiographs - purposes

Answer 4

• imaging larger sections of the dentition
• alternative for patient that cannot tolerate intra oral radiography
• imaging non-dentoalveolar regions

Question 5

When taking a lateral cephalogram, how far should the receptor be from the x-ray focal spot and why?

Answer 5

1.5 to 1.8m to minimise magnification

Question 6

How to improve visualisation of soft tissues on a lateral cephalogram

Answer 6

• place an aluminium wedge filter in the unit to attenuate the specific area of the beam exposing the soft tissues
  or
  use software to enhance the soft tissues post-exposure

Question 7

Why is a thryroid collar worn when taking a lat ceph?

Answer 7

thyroid gland is relatively radiosensitive

Question 8

indications for panoramic radiography

Answer 8

• assessment of dental pathology
• assessment of presence/position of unerupted teeth
• detection of mandibular fractures
• evaluating lesions/conditions affecting jaws e.g. cysts, tumours etc