extraoral imaging

Question 1

Panoramic X-ray

the tubehead rotates behind the patient’s head

machine that captures the entire mouth in a single image

Answer 1

• evaluating large areas of the skull
• detecting impacted teeth, eruption patterns, and TMJ problems

Question 2

what are the downsides of a panoramic x-ray?

Answer 2

usually not clear and detailed enough to assess caries and periodontal diseases

Question 3

Focal trough

Answer 3

horseshoe-shaped narrow curved space where the structure is captured

Question 4

objects inside the focal trough are?

Answer 4

clear

Question 5

objects outside the focal trough are?

Answer 5

blurred

Question 6

Collimator

Answer 6

a lead plate with a narrow vertical opening

Question 7

panoramic x-ray

what can the clinician control?

Answer 7

the milliamperage and kilovoltage from the exposure setting

Question 8

Can the exposure time be changed?

Answer 8

No

Question 9

T/F: for x-rays, all objects should be removed from the mouth

including eyewear, earrings, nose rings, and other jewelry

dentures, retainers, tongue ring, etc

Answer 9

True

Question 10

what should be worn to protect the patient’s back and shoulder?

Answer 10

a lead apron (without a thyroid collar)

to be worn like a poncho

wearing a thyroid collar would result in a shark’s fin artifact

Question 11

which position of the machine is used to achieve the ideal position?

Answer 11

head position (consists of chin rest, notched bite-block, forehead rest, and lateral head support)

Question 12

Frankfort plane

Answer 12

line from the bottom of the orbit to the top of the auditory meatus

Question 13

Frankfort plane should be — to the floor

Answer 13

parallel

Question 14

the patient should look forward and tip their chin?

Answer 14

slightly down (towards the floor)

this elevates the posterior palate so that it doesn’t overlap with the apices of the maxillary teeth

Question 15

The midsaggital plane should be — to the floor

Answer 15

perpendicular

Question 16

right before the exposure, the patient should swallow and — ?

Answer 16

lift the tip of the tongue up to the roof of the mouth

Question 17

failure in lifting the tip of the tongue up to the roof of the mouth results in?

Answer 17

shadows over the maxillary teeth

Question 18

shark’s fin error

Answer 18

lead collar above line

fix by lowering collar position

Question 19

an exaggerated smile means?

Answer 19

patient’s chin is tipped too far down

fix by repositioning the chin

Question 20

a flat or reversed smile means?

Answer 20

patient’s chin is tipped too far up

fix by repositioning the chin

Question 21

if the Maxillary incisors’ roots are blurred?

Answer 21

the chin is tipped too far up

Question 22

if one side of the x-ray shows larger teeth/condyle?

Answer 22

the patient’s head is twisted

reposition the head, midsagittal plane perpendicular to the floor (the larger side is the distant side)

Question 23

Washington monument error

Answer 23

a white straight opacity in the middle of the image due to slumping caused ghost image of the spine

move patient’s feet forward, straighten the spine and lean backward

Question 24

Air space error

Answer 24

Airway shadow in an arch shapeover maxillary teeth due to tongue not touching the roof of the mouth

have the patient swallow and reposition the tongue

Question 25

Thick and wide anterior teeth mean?

Answer 25

chin placed behind the focal trough ## Footnote reposition the chin forward, bite at the notch of the stick

Question 26

Skinny anterior teeth mean?

Answer 26

chin placed too far forward ## Footnote reposition the chin back, bite at the notch of the stick

Question 27

small incisors

Answer 27

head too foward error

Question 28

enlarged incisors

Answer 28

head too far back error

Question 29

a ghose image indicates that?

Answer 29

accessories have not been removed ## Footnote Ghost image looks similar to the real object but is on the opposite of the image and slightly higher (e.g., an earring on the right side produces a ghost image on the left side)

Question 30

# radiograph anatomical landmarks Incisive foramen

Answer 30

passageway for nasopalatine nerves. Small **radiolucent oval** between roots of maxillary central incisors (should not be confused with periapical disease)

Question 31

# radiograph anatomical landmarks Median palatal suture

Answer 31

vertical **radiolucent thin line** in the middle of the palate (should not be mistaken for a fracture)

Question 32

Nasal septum

Answer 32

thin wall that divides the nasal cavity into two **radiopaque vertical strip**

Question 33

Nasal spine

Answer 33

projection of bone anteriorly - **radiopaque triangle** shape at median palatal suture where nasal septum and fossae meet

Question 34

Nasal cavity (nasal fossae)

Answer 34

large air-filled space above and behind the nose in the middle of the face **radiolucent oval** shapes superior to central incisors

Question 35

Inverted Y

Answer 35

junction where the *nasal fossa* and the *maxillary sinus* meet. Most commonly found superior to the *maxillary canine apex*

Question 36

Maxillary sinus

Answer 36

*hollow* spaces in bone superior to *molar* and *premolar*

Question 37

Maxillary tuberosity

Answer 37

distal portion of the alveolar process. Rounded, radiopaque elevation *distal to third molar regions*

Question 38

Hamulus

Answer 38

extension of medial pterygoid plate of sphenoid bone - radiopaque *hook-like* protrusion posterior to maxillary tuberosity

Question 39

Zygomatic process

Answer 39

protruded arch of the zygomatic bone. *U-shaped* radiopaque band superior to molar apices

Question 40

Coronoid process

Answer 40

*anterior* portion of the ramus Radiopaque triangular projection usually superimposed over maxillary tuberosity

Question 41

Genial tubercles

Answer 41

4 bony spines used for muscle attachment of the genioglossus and geniohyoid muscles Circular radiopacities inferior to central incisor apices

Question 42

Lingual foramen

Answer 42

exit for incisive vessel branches The radiolucent circle inside the opaque genial tubercles on the mandibular anteriors

Question 43

Mental foramen

Answer 43

*Opening* for mental nerve and vessels inferior to mandibular premolar apices. Round *radiolucent* area sometimes mistaken for periapical disease

Question 44

Mental ridge

Answer 44

Ridge of bone located on the *anterior surface of the mandible* Bilateral radiopaque lines, starting inferior to premolar apices and extending anteriorly to the midline

Question 45

External oblique ridge

Answer 45

Linear area of bone on the external surface of the mandible The radiopaque line running anterior from the ramus across the molars

Question 46

Internal oblique ridge (mylohyoid)

Answer 46

Elevated long area on the internal surface of the mandible The radiopaque line running along the premolar and molar apices. It is usually positioned below the external oblique ridge on radiographs

Question 47

Submandibular fossa

Answer 47

radiolucent band that runs inferior to the mylohyoid line and apices of molars

Question 48

Nutrient canals

Answer 48

thin vertical *radiolucent* lines near the teeth, may be mistaken for bone fractures

Question 49

Mandibular canal

Answer 49

*Radiolucent* horizontal band outlined with a thin line of cortical bone Inferior alveolar nerve and arteries pass inside the canal. Stretches from the mandibular foramen to the mental foramen

Question 50

Cephalometric projection

Answer 50

shows the *lateral* view of the skull -Helps in evaluating trauma and facial growth

Question 51

Lateral jaw exposure

Answer 51

Evaluates the posterior portion of the mandible or lateral areas that are too large to capture for periapical receptors -Helps in evaluating growth and development, diseases, and trauma

Question 52

Posteroanterior projection

Answer 52

shows the frontal and ethmoid sinuses, orbits, and nasal cavities

Question 53

Water’s projection

Answer 53

provides images of the maxillary *sinus*

Question 54

MRI (magnetic resonance imaging)

Answer 54

used for images of the soft tissue, TMJ, etc. NOTE: If the image shows soft structures (not bone), an MRI was used

Question 55

CT, CAT scan

Answer 55

computer tomography (CT), also called computed axial tomography (CAT) scan, produces a two-dimensional image of a three-dimensional structure -Helpful for implant planning, soft tissue lesions, and salivary glands inspections

Question 56

Cone-beam computed tomography (CBCT)

Answer 56

produces a three-dimensional image of a structure

Question 57

What is a CBCT useful for?

Answer 57

Inplant planning, TMJ issues, and soft tissue lesions Provides information for the articular joints and soft tissue when detecting issues with TMJ

Question 58

How does a CBCT operate? (ie. pano/3d machine)

Answer 58

The arm rotates around the patient’s head in 360° During this process, 200-600 two-dimensional images are formed which are combined to produce a 3D image

Question 59

Which scan requires lower doses of radiation between CT exposures and CBCT scans?

Answer 59

CBCT; comparable to 3-4 full-mouth series radiographs

Question 60

Sialography

Answer 60

detects salivary stones and other blockages