dental panoramic OPG

Question 1

indicattions for an OPG

Answer 1

1) when a lesion/ unerupted is of a size or position that it cannot be demonstrated fully with intra oral films
2) pathology in all 4 quadrants of the jaws
3) for periodontal disease when pockets greater than 6mm
4) assessment of third molars prior to surgical removal (usually sectional)
5) as part of an orthodontic assessment in the mixed dentition
6) following trauma
7) for implant planning

Question 2

principles of image OPG formaiton

Answer 2

Panoramic radiograph is a tomogram (slice) through the jaws

• slice is thin anteriorly and thicker posteriorly
• operator has to position patient so jaws lie in the focal trough
• structures within the focal trough are sharp
• anatomy outside the focal trough is distorted

Question 3

ghost image on OPG

Answer 3

A ghost image is formed when an object lies between the centre of rotation of the x ray tube and the image receptor
- appear on the opposite side to the real image and are higher up and blurred
- due to x rays taking images twice
higher
opposite side
blurred

Question 4

patient too far in on OPG leads to

Answer 4

• anterior teeth in both jaws narrow and blurred
• premolars overlapped
• lots of cervical spine on the film

Question 5

patient too far out from trough leads to

Answer 5

• chin not on chin rest
• incisors are widened and blurred
• condyles missed of the edges of the film

Question 6

chin up OPG leads to

Answer 6

• roots of upper incisors are blurred
• hard palate can overlap upper teeth apices
• condyles lost off the film edges
• grumpy face curve

Question 7

chin down OPG leads to

Answer 7

• lower incisor roots blurred
• Hyoid bone projected over mandible
• smiley face sign

Question 8

swallowing during exposure of OPG

Answer 8

• well defined air density lucency above the tongue dorsum
• unilateral distortion of the hyoid bone
• shouldn’t affect position of jaws