Dentals - Extra-Oral

Question 1

why are panoramic views taken?

Answer 1

to allow a more general assessment of the teeth and jaws

Question 2

what are 6 reasons why a panoramic view would be taken?

Answer 2

assessment of third molars
prior to multiple extractions
jaw #s
severe periodontal disease
orthodontic assessment
TMJ problems

Question 3

give 5 more reasons why a panoramic view would be taken

Answer 3

assessment of large pathological lesions
when intra-oral radiography is impossible due to gagging or trismus
patients with gross decay
assessment for implants
where a bony lesion or an unerupted tooth cannot be demonstrated

Question 4

how are panoramic views taken?

Answer 4

type of tomography (slice through patient)
tube and film move round head
patient positioning is crucial so the jaws are in the focal trough

Question 5

what 5 steps are carried out to prep the patient

Answer 5

justify request
check medical history
confirm patients identity
ask patients to remove earrings, glasses, necklaces and dentures
explain machine movement to patient, especially children

Question 6

what 6 steps are taken to position the patient

Answer 6

position patient upright - not slumped
guide patients head between head clamps
ask patient to bite the bite rod gently
tilt head forward
teeth and jaw positioned with focal trough
ensure patient places their tongue against their palate during the exposure

Question 7

what can be used to guide positioning?

Answer 7

positioning lights

Question 8

what are 3 image criteria for a well positioned film

Answer 8

symmetrical
no magnification or diminution of teeth
occlusal plate flat or slight downward curve

Question 9

what are the 6 common positioning errors

Answer 9

too far in
too far out
chin up 
chin down
head rotated
patient slumped

Question 10

what will occur on the image if the patient is too far in - 3 points

Answer 10

the anterior teeth will be blurred and narrow in appearance
the premolars will be overlapped
the c spine may be superimposed on the rami

Question 11

what will occur on the image if the patient is too far out - 2 points

Answer 11

the anterior teeth will be blurred and wide in appearance

the condyles may fall outside the sides of the film

Question 12

what will occur on the image if the patients is in a chin up position - 3 points

Answer 12

the roots of the upper incisors will be blurred
the condyles may be lost on the side of the film
the hard palate may be projected over the upper roots apices

Question 13

what will occur on the image if the patient is in the chin down position - 3 points

Answer 13

the lower incisor roots will be blurred
the hyoid bone may be projected over the mandible
the occlusal plane will have characteristic “smile sign”

Question 14

what will occur on the image if the patients head is rotated - 2 points

Answer 14

the teeth on one side of the midline will have overlapping contacts and will be magnified relative to those on the other side

the width of the mandibular ramus on each side will also be different

Question 15

what will occur on the image if the patient is slumped - 1 point

Answer 15

this results in an opaque ghost image of the c spine to be projected over the midline of the film

Question 16

describe a ghost image - 3 points

Answer 16

formed when the object is located between the x-ray source and the centre of rotation
appear on the opposite side from the real image
always higher up and blurred

Question 17

what is included in the image evaluation - 10 points

Answer 17

ID label should not obscure the image
whole of mandible imaged
bone levels demonstrated
incisors biting edge to edge 
no artefacts
no radiolucent air shadow
minimisation of c spine shadow
correct anatomical markers
all teeth in focus
no movement

Question 18

why are lateral cephalometric view taken - 3 points

Answer 18

as part of an orthodontic assessment
accurately show the position of teeth and their relationship to the skull
orthognathic assessment

Question 19

how are lateral ceph’s taken

where is x-ray tube and why?

why is a filter used?

Answer 19

pt set up in a cepalosat with rods in ears and against the bridge of the nose - puts patient in known position and allows review radiographs to be taken in the exact same way
at 2m away to get a parallel beam to minimise magnification
so facial soft tissue profile is seen

Question 20

patient positioning for lateral ceph - 6 points

Answer 20

gently place ear plugs into EAMs
Frankfort plane should be parallel to the floor 
position the nasal support
align light to outer canthus of eye 
ask patient to bite on the back teeth
lips should be relaxed

Question 21

image evaluation for lateral ceph - 6 points

Answer 21

ear plugs should be superimposed
facial structures should be superimposed
upper occlusal plane parallel to floor
molars in occlusion
soft tissue outline from forehead to chin
no movement

Question 22

what are 6 clinical indications for lateral oblique mandible

Answer 22

when an OPG is difficult to perform on young children, elderly or special needs
#ed mandible
assessment of large pathologies
when periapical radiography is not possible
salivary glands
TMJs

Question 23

what does CBCT stand for?

Answer 23

Cone Beam Computed Tomography

Question 24

what is CBCT

Answer 24

compact, faster, and safer version of regular CT
uses cone-shaped x-ray beam
easily accessible by patients

Question 25

what 3 things are dramatically reduced

Answer 25

the size of scanner, radiation dose (up to 100x less) and time needed for scanning (about 1 minute)