NDAEB Exam Prep . 292 Questions and Correct
Answers, With Complete Solution 2024. Actual
Exam Questions Included.
What two basic methods are used to acquire a digital x-ray image?
Direct imaging(sensor) & indirect imaging(PSP)
Advantages of Digital Radiography
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
Cost, converting previous records to digital, learning the computer software, thickness and rigidity of
sensors, infection control
What is intraoral film composed of?
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?
The image on the film that is not yet visible because it has not been processed.
What does 'film speed' refer to?
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?
True
What is the fastest film speed currently available?
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?
Intraoral film, extraoral film, and duplicating film.
When does a "Herringbone" pattern occur on dental film?
When it is placed in the mouth backwards.
What are the 5 basic sizes that intraoral film comes in?
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?
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?
Bisecting & Paralleling
5 Basic Rules of the Paralleling Technique
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?
To ensure an area is not omitted or exposed twice.
What occurs if the horizontal angulation is incorrect?
Overlapping of teeth.
What two errors can occur if the vertical angulation is incorrect?
Foreshortened or elongated images.
What qualities must an endodontic x-ray have?
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:
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:
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?
Use of a cone-shaped x-ray beam to acquire three-dimensional information.
What is a film grid? (used for extraoral imaging)
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?
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?
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?
Ghost images
If a lead apron is incorrectly placed on a pt during a panoramic radiograph, what occurs?
"Lead Apron Artifact" a radiopaque cone-shaped artifact results.
What happens if a patient's chin is positioned too high during a pan?
It will create a "reverse smile line"
What happens if a patient's chin is positioned too low during a pan?
It will create an "exaggerated smile line"
What are three types of stress and strain?
Tensile stress: pulls and stretches a material Ex. tug-of-war
Compressive stress: pushes a material together. ex. chewing
Shear stress: the breakdown of material as the result of something sliding over two areas. ex. cutting
with scissors.
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