NDAEB Exam Prep questions and correct
answers 2024
What two basic methods are used to acquire a digital x-ray image? -
answer-Direct imaging(sensor) & indirect imaging(PSP)
Advantages of Digital Radiography - answer-Immediate viewing of
images, less radiation, no chemicals, ability to enhance images,
communication with other dentists, no more lost films, remote
consultation capability
Disadvantages of Digital Radiography - answer-Cost, converting
previous records to digital, learning the computer software, thickness
and rigidity of sensors, infection control
What is intraoral film composed of? - answer-Film Base - Clear
Cellulose Acetate
Thin Adhesive Layer
Silver Halide Crystals - absorb radiation
A protective layer to protect the emulsion surface.
What is a latent image? - answer-The image on the film that is not yet
visible because it has not been processed.
What does 'film speed' refer to? - answer-The amount of radiation that
is required to produce a radiograph of standard density.
True or false: The larger the silver halide crystals, the faster the film
speed? - answer-True
,What is the fastest film speed currently available? - answer-F-Speed.
(It reduces patient exposure to radiation by 20-60% compared to E or
D speed film)
What are the 3 types of x-ray film used in dental radiography? -
answer-Intraoral film, extraoral film, and duplicating film.
When does a "Herringbone" pattern occur on dental film? -
answer-When it is placed in the mouth backwards.
What are the 5 basic sizes that intraoral film comes in? - answer-Child
Size: 0
Narrow Anterior: 1
Adult Size: 2
Preformed bitewing: 3 (infrequently used)
Occlusal: 4
What are two common extraoral radiographs taken? -
answer-Panoramic and Cephalometric.
What is an intensifying screen? - answer-A device that intensifies or
increases the effect of radiation and thus decreases the amount of
exposure time needed. It is coated with phosphor which gives off light
when struck by x-radiation.
What are the 5 steps in processing film? - answer-1. Developing
(reduce the silver halide crystals into black metallic silver)
2. Rinsing (remove developer from film)
3. Fixing. (use an acidic solution to remove unexposed silver halide
crystals)
4. Washing (wash the film)
,5. Drying
What are the two techniques that can be used for exposing intraloral
images? - answer-Bisecting & Paralleling
5 Basic Rules of the Paralleling Technique - answer-1. Placement: it
must cover correct teeth to be examined
2. Position: it must be parallel to the long axis of the tooth.
3. Vertical Angulation: Central ray must be directed perpendicular to
the receptor & tooth.
4. Horizontal Angulation: Central ray must be directed through the
contact areas.
5. Central Ray: it must be centered on the receptor.
Why is it important to have an 'exposure sequence' for receptor
placement? - answer-To ensure an area is not omitted or exposed
twice.
What occurs if the horizontal angulation is incorrect? -
answer-Overlapping of teeth.
What two errors can occur if the vertical angulation is incorrect? -
answer-Foreshortened or elongated images.
What qualities must an endodontic x-ray have? - answer-Tooth
centered on the image
At least 5mm of bone visible beyond apex of the tooth
The image is as anatomically accurate as possible
Two methods of mounting radiographs are: - answer-1. Labial
mounting method: radiographs placed in the mount with the raised
dots facing up (as if the viewer is looking directly at the pt)
, 2. radiographs placed in the mount with the raised dots facing down
(as if the viewer is inside the patients mouth looking out)
Two types of panoramic machines are in use today: -
answer-Film-based imaging & direct digital imaging. The main
difference is the image receptor, digital units use a sensory array
rather than film.
What is Cone Beam Computed Tomography? - answer-Use of a
cone-shaped x-ray beam to acquire three-dimensional information.
What is a film grid? (used for extraoral imaging) - answer-It is used to
reduce the amount of scatter radiation that reaches an extraoral film
during exposure.
What is a Lateral Cephalometric Projection used for? - answer-Used
to evaluate facial growth and development, trauma, disease, and
developmental abnormalities. It shows the bones of the face and skull
as well as the soft tissue profile.
What is a Posteroanterior Projection used for? - answer-Used to
evaluate facial growth and development, trauma, disease, and
development abnormalities. It shows the frontal and ethmoid sinuses,
the orbits, and the nasal cavities.
What happens if a patient does not remove jewellery or
metallic/radiodense objects from their head/neck? - answer-Ghost
images
If a lead apron is incorrectly placed on a pt during a panoramic
radiograph, what occurs? - answer-"Lead Apron Artifact" a radiopaque
cone-shaped artifact results.
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