NDAEB Exam Prep – Questions & Accurate Answers
What two basic methods are used to acquire a digital x-ray image? Right
Ans - Direct imaging(sensor) & indirect imaging(PSP)
Advantages of Digital Radiography Right Ans - 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 Right Ans - Cost, converting previous
records to digital, learning the computer software, thickness and rigidity of
sensors, infection control
What is intraoral film composed of? Right Ans - 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? Right Ans - The image on the film that is not yet
visible because it has not been processed.
What does 'film speed' refer to? Right Ans - 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?
Right Ans - True
What is the fastest film speed currently available? Right Ans - 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? Right Ans -
Intraoral film, extraoral film, and duplicating film.
When does a "Herringbone" pattern occur on dental film? Right Ans - When
it is placed in the mouth backwards.
,What are the 5 basic sizes that intraoral film comes in? Right Ans - Child
Size: 0
Narrow Anterior: 1
Adult Size: 2
Preformed bitewing: 3 (infrequently used)
Occlusal: 4
What are two common extraoral radiographs taken? Right Ans - Panoramic
and Cephalometric.
What is an intensifying screen? Right Ans - 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? Right Ans - 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?
Right Ans - Bisecting & Paralleling
5 Basic Rules of the Paralleling Technique Right Ans - 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?
Right Ans - To ensure an area is not omitted or exposed twice.
What occurs if the horizontal angulation is incorrect? Right Ans -
Overlapping of teeth.
,What two errors can occur if the vertical angulation is incorrect? Right Ans
- Foreshortened or elongated images.
What qualities must an endodontic x-ray have? Right Ans - 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: Right Ans - 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: Right Ans - 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? Right Ans - Use of a cone-
shaped x-ray beam to acquire three-dimensional information.
What is a film grid? (used for extraoral imaging) Right Ans - 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? Right Ans - 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? Right Ans - 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? Right Ans - Ghost images
, If a lead apron is incorrectly placed on a pt during a panoramic radiograph,
what occurs? Right Ans - "Lead Apron Artifact" a radiopaque cone-shaped
artifact results.
What happens if a patient's chin is positioned too high during a pan? Right
Ans - It will create a "reverse smile line"
What happens if a patient's chin is positioned too low during a pan? Right
Ans - It will create an "exaggerated smile line"
What are three types of stress and strain? Right Ans - 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.
What is amalgam alloy powder composed of? Right Ans - Silver - gives it its
strength.
Tin - gives it workability and strength.
Copper - gives it strength and resistance to corrosion.
Zinc - to suppress oxidation.
What is the composition of a composite resin? Right Ans - 1. An organic
resin matrix.
2. Inorganic fillers.
3. A coupling agent.
4. pigments.
What is the resin matrix in a composite resin? Right Ans - A fluid-like
material called dimethacrylate or BIS-GMA.
What is the filler in a composite resin? Right Ans - Inorganic fillers in a
composite resin include quartz, glass, silica particles, and colorants. They add
strength and other characteristics needed in a restorative material.
Composites are classified by particle size as: Right Ans - Megafill, macrofill,
midifill, minifill, microfill, and nanofill.
What two basic methods are used to acquire a digital x-ray image? Right
Ans - Direct imaging(sensor) & indirect imaging(PSP)
Advantages of Digital Radiography Right Ans - 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 Right Ans - Cost, converting previous
records to digital, learning the computer software, thickness and rigidity of
sensors, infection control
What is intraoral film composed of? Right Ans - 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? Right Ans - The image on the film that is not yet
visible because it has not been processed.
What does 'film speed' refer to? Right Ans - 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?
Right Ans - True
What is the fastest film speed currently available? Right Ans - 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? Right Ans -
Intraoral film, extraoral film, and duplicating film.
When does a "Herringbone" pattern occur on dental film? Right Ans - When
it is placed in the mouth backwards.
,What are the 5 basic sizes that intraoral film comes in? Right Ans - Child
Size: 0
Narrow Anterior: 1
Adult Size: 2
Preformed bitewing: 3 (infrequently used)
Occlusal: 4
What are two common extraoral radiographs taken? Right Ans - Panoramic
and Cephalometric.
What is an intensifying screen? Right Ans - 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? Right Ans - 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?
Right Ans - Bisecting & Paralleling
5 Basic Rules of the Paralleling Technique Right Ans - 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?
Right Ans - To ensure an area is not omitted or exposed twice.
What occurs if the horizontal angulation is incorrect? Right Ans -
Overlapping of teeth.
,What two errors can occur if the vertical angulation is incorrect? Right Ans
- Foreshortened or elongated images.
What qualities must an endodontic x-ray have? Right Ans - 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: Right Ans - 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: Right Ans - 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? Right Ans - Use of a cone-
shaped x-ray beam to acquire three-dimensional information.
What is a film grid? (used for extraoral imaging) Right Ans - 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? Right Ans - 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? Right Ans - 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? Right Ans - Ghost images
, If a lead apron is incorrectly placed on a pt during a panoramic radiograph,
what occurs? Right Ans - "Lead Apron Artifact" a radiopaque cone-shaped
artifact results.
What happens if a patient's chin is positioned too high during a pan? Right
Ans - It will create a "reverse smile line"
What happens if a patient's chin is positioned too low during a pan? Right
Ans - It will create an "exaggerated smile line"
What are three types of stress and strain? Right Ans - 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.
What is amalgam alloy powder composed of? Right Ans - Silver - gives it its
strength.
Tin - gives it workability and strength.
Copper - gives it strength and resistance to corrosion.
Zinc - to suppress oxidation.
What is the composition of a composite resin? Right Ans - 1. An organic
resin matrix.
2. Inorganic fillers.
3. A coupling agent.
4. pigments.
What is the resin matrix in a composite resin? Right Ans - A fluid-like
material called dimethacrylate or BIS-GMA.
What is the filler in a composite resin? Right Ans - Inorganic fillers in a
composite resin include quartz, glass, silica particles, and colorants. They add
strength and other characteristics needed in a restorative material.
Composites are classified by particle size as: Right Ans - Megafill, macrofill,
midifill, minifill, microfill, and nanofill.
