Question 1

Extraoral film is available in which sizes?

Accepted Answer

Extraoral film is typically available in larger sizes to accommodate the broader areas being imaged outside the mouth, such as the jaw or skull. The sizes mentioned in option A, 5x7-inch or 8x10-inch, are standard for extraoral radiographic films.

Question 2

The best extraoral projection to detect a fracture of the zygomatic arch is the posterioranterior projection.

Accepted Answer

The best extraoral projection to detect a fracture of the zygomatic arch is the submentovertex (SMV) projection, as it provides a clear view of the zygomatic arches without superimposition of other facial bones.

Question 3

Identify the projection used to view the maxillary sinus and middle third of the face:

Accepted Answer

The Waters' view is used to visualize the maxillary sinus and middle third of the face. The other projections listed may be used for other parts of the head and neck.

Question 4

Identify the projection used to view the entire skull in the sagittal plane:

Accepted Answer

The lateral skull projection is used to view the entire skull in the sagittal plane, providing a side view of the skull.

Question 5

For the submentovertex projection,the patient is positioned with the nose and forehead touching the receptor.The central ray is directed at a zero-degree vertical angulation,aimed at the external occipital protuberance.For the posteroanterior projection,the cassette is positioned on the vertex of the patient's skull,and the central ray is directed from underneath the patient's chin (menton)perpendicular to the cassette.

Accepted Answer

Both statements are false. In the submentovertex projection, the patient's head is tilted back so that the vertex is closest to the receptor, and the central ray is directed from below the chin. In the posteroanterior projection, the patient's forehead and nose touch the receptor, and the central ray is directed from the back of the head.

Question 6

The limitation for using the posterior anterior projection for visualizing the maxillary sinus is:

Accepted Answer

The superimposition of the zygomatic arch over the maxillary sinus on the posterior anterior projection limits its ability to fully visualize the maxillary sinus.

Question 7

The Waters' projection is useful for the diagnosis of what?

Accepted Answer

The Waters' projection is a radiographic projection that is useful for visualizing the maxillary sinuses. It is achieved by angling the x-ray beam so that it passes through the nasal bones and maxillary sinuses, and then directing it towards the film or detector. This projection is commonly used for evaluating sinusitis, fractures of the facial bones, and tumors in the area. It is not useful for diagnosing parotid gland or impacted teeth issues, and while it can sometimes show mandibular molars, other projections such as the panoramic view are generally more effective for this purpose.

Question 8

What is the target-receptor distance (FFD)for the Water's View?

Accepted Answer

The target-receptor distance (FFD) for the Water's View, which is a radiographic view used to visualize the paranasal sinuses, is typically 36 inches.

Question 9

The use of grids for extraoral radiography is not common in dental practice and is mostly confined to cephalometric and TMJ radiographs.The function of the grid is to decrease the amount of scatter radiation originating in the object.

Accepted Answer

Both statements are accurate. The use of grids in dental practice is indeed not common and is primarily limited to specific types of radiographs such as cephalometric and TMJ. The primary function of the grid is to reduce scatter radiation, which improves image quality by preventing unwanted exposure.

Question 10

All of the following are indications for use of extraoral radiography EXCEPT one.Which one is the EXCEPTION?

Accepted Answer

Extraoral radiography is not indicated for patients needing a periapical, as periapical radiography is a type of intraoral radiography that captures an image of the entire tooth, from the crown to the root tip. Extraoral radiography is used to capture an image of the entire maxilla or mandible, or a specific area such as the temporomandibular joint or sinuses. Patients with trismus, handicapped patients, and patients with temporomandibular joint ankylosis may have difficulty opening their mouths for intraoral radiography, making extraoral radiography a better choice.

Question 11

The lateral oblique projection of the mandible is used for surveying one side of the mandible entirely from the distal of the canine to the angle of the ramus,the ramus,condyle,and coronoid process.

Accepted Answer

The lateral oblique projection of the mandible is used for surveying one side of the mandible entirely from the distal of the canine to the angle of the ramus, the ramus,condyle, and coronoid process.

Question 12

Which of the following methods is best for radiographing an impacted third molar?

Accepted Answer

The lateral oblique projection of the mandible is best for radiographing an impacted third molar because it allows for visualization of the tooth and the surrounding bone without superimposition of other teeth or structures.

Question 13

Extraoral films are processed:

Accepted Answer

Extraoral films require a safelight of less intensity to prevent fogging, as they are more sensitive to light than intraoral films.

Question 14

The extraoral projection used in cephalometric analysis is the lateral skull projection.

Accepted Answer

The lateral skull projection (also known as lateral cephalogram) is one of the extraoral projections used in cephalometric analysis. It provides a side view of the skull and facial structures, allowing for measurements and analysis of skeletal and dental relationships.

Question 15

For patients with bilateral mandibular impactions,the right and left lateral oblique techniques have been replaced by:

Accepted Answer

Panoramic films provide a more comprehensive and accurate view of the entire mandible, making them the preferred choice for patients with bilateral mandibular impactions. Occlusal films, lateral skull projections, and posterior anterior projections do not provide as much detail or coverage.

Question 16

Which of the following is the average exposure time for an adult for a lateral skull projection?

Accepted Answer

The answer of Which of the following is the average...

Question 17

Identify the projection used to view the sphenoid and ethmoid sinuses:

Accepted Answer

The submentovertex (SMV) projection is used to view the sphenoid and ethmoid sinuses.

Question 18

Depending on the type of panoramic unit,rigid or flexible cassettes are used.

Accepted Answer

This statement is true. Rigid or flexible cassettes can be used depending on the type of panoramic unit.

Question 19

Cassettes with intensifying screens are used in extraoral radiography to increase patient exposure.

Accepted Answer

Cassettes with intensifying screens are used in extraoral radiography to decrease patient exposure by amplifying the amount of light produced by the x-ray photons.

Question 20

Identify the projection used in tomography as a scout film to determine condylar position:

Accepted Answer

The submentovertex projection is used in tomography as a scout film to determine the condylar position because it provides a clear view of the condyles in relation to the rest of the skull, which is essential for assessing their position.

Quiz 13: Extraoral Techniques