Extra Oral

Question 1

what are the 3 extra oral views related to the mandible?

Answer 1

postero-anterior mandible
lateral oblique of mandible
DPT

Question 2

what are the 3 extra oral views relating to the maxilla and cranium?

Answer 2

lateral cephalogram
occipito-mental views
sialography

Question 3

what are the 3 positioning landmarks?

Answer 3

radiographic base line
frankfort plane
maxillary occlusal plane

Question 4

where is the radiographic base line?

Answer 4

outer canthus of eye to EAM

Question 5

where is frankfort plane?

Answer 5

IOB to upper border EAM

Question 6

where is the maxillary occlusal plane?

Answer 6

ala of nose to tragus of ear

Question 7

what extra oral view uses the frankfort plane?

Answer 7

DPT

Question 8

what extra oral view uses the maxillary occlusal plane?

Answer 8

cone beam CT

Question 9

What equipment do you need?

Answer 9

skull unit/ cephalometric unit
image receptor
anti-scatter grid

Question 10

what is Compton scattering?

Answer 10

when x-rays pass through tissues some are scattered

Question 11

what is used to stop scattering?

Answer 11

anti-scatter grid

Question 12

what does scattering result in?

Answer 12

grey image lacking contrast

Question 13

what does an anti-scatter grid contain?

Answer 13

lead slats alternating with plastic

Question 14

what is a postero-anterior mandible view used for?

Answer 14

fractures medio-lateral displacement
cysts and malignancy causing medio-lateral expansion/ bone destruction
good visualisation of posterior body and ramus

Question 15

what position is patient for PA mandible?

Answer 15

facing film
RB horizontal 90 degree to film
centre of beam to mid-line of patient

Question 16

where is the midline?

Answer 16

between eyes/ external protuberance

Question 17

how may a PA mandible view look if RB not 90 degrees to receptor?

Answer 17

cant see the head and neck of condyle

Question 18

what is a lateral oblique jaw view used for?

Answer 18

fracture of body, ramus and condyle
pathology
wisdom teeth
dental assessment for patients with ASN
caries in children who cant tolerate bitewings

Question 19

what positioning is used with skull unit for LO jaw view when querying a fracture?

Answer 19

isocentric positioning

Question 20

what is isocentric positioning?

Answer 20

patient supine
position for area to imaged
rotate machine into horizontal plane
angle 25 degrees towards head
tilt top of patients head towards film

Question 21

what positioning is used with the skull unit for LO jaw view when visualising dental pathology?

Answer 21

vertical angulation

Question 22

how is vertical angulation for LO jaw view obtained?

Answer 22

patient hold cassette against and parallel to area examined
tube head beneath lower border of body of mandible that ISNT being examined
aim tube towards teeth
angle tube head slightly upwards

Question 23

what is the most common positioning for LO jaw view?

Answer 23

horizontal angulation

Question 24

how is horizontal angulation for LO jaw view obtained?

Answer 24

patient hold cassette against and parallel to area under examination
tube head is positioned along occlusal plane just below the ear towards maxillary and mandibular teeth being examined
aims through radiographic keyhole

Question 25

when is cephalometric radiography used?

Answer 25

orthodontic assessment pre orthognathic surgery

Question 26

what is used to take a cephalometric radiograph?

Answer 26

Cephalostat

Question 27

how is a lateral ceph set up?

Answer 27

mid sagittal plane parallel to film patient positioned with ear rods frankfort plane horizontal centre of beam aimed at EAM teeth in occlusion

Question 28

how is magnification reduced?

Answer 28

long focus to patient distance short patient to film distance

Question 29

how do you calculate magnification?

Answer 29

magnification rod on image

Question 30

how are soft tissues seen on a lateral ceph?

Answer 30

aluminium filter positioned over anterior face

Question 31

how is PA ceph set up?

Answer 31

patient positioned for PA mandible x-ray beam aimed at midline level with EAM RB parallel to floor

Question 32

when would you use occipito-mental views?

Answer 32

facial bone fractures - le fort fractures pathology

Question 33

what are the 3 occipito-mental view angulations?

Answer 33

OM 0 OM 10 OM 30

Question 34

How is OM view set up?

Answer 34

patient face film holder nose and chin touching holder RB 45 degree to film aim centre of x-ray beam to midline of patient angle beam 10 degree or 30 degree to feet

Question 35

what does increasing angulation of OM view do?

Answer 35

projects dense bones of skull base down away from facial structures improves view of zygomatic arch

Question 36

what is cone beam computed tomography?

Answer 36

3D reconstruction of anatomy