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NDAEB EXAM PREP QUESTIONS AND ANSWERS
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NDAEB EXAM PREP QUESTIONS AND ANSWERS
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NDAEB EXAM PREP QUESTIONS AND ANSWERSWhat 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.
What happens if a patient's chin is positioned too high during a pan? - answer- It will
create a "reverse smile line"
When a denture is to be relined, how long is the patient without it for? - answer- 8-24
hours
What are the 3 main types of implants? - answer- Endosteal- most common. surgically
placed into the jawbone. 1. the titanium implat is embedded into the jawbone during
stage 1. 2. titanium abutment screw is screwed into the implant after osseointegration of
the implant. 3. abutment post or cylinder attaches to the artificial tooth or denture.
Subperiosteal- a metal frame that is placed under the periosteum and on top of the
bone. Not into the bone. Good for pt who do not have sufficient alveolar ridge to support
endosteal type implants. Often used to support mandibular complete denture.
Transosteal Implant- inserted through the inferior border of the mandible and into the
edentulous area. used with pt with severely resorbed ridges and there are no other
options.
What is osseointegration? - answer- Process by which the living cells of the jawbone
naturally grow around the implanted dental supports.
How long is the osseonintegration period? - answer- About 3-6 months.
What material is commonly used to make an implant? - answer- Titanium because of its
compatibility with bone and oral tissues. It may be coated with hydroxyapatite , a
ceramic substance that rapidly osseonintegrates the implant to the bone.
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