Occlusal Radiography

Question 1

Occlusal radiographs image receptor size

Answer 1

7x5cm

Question 2

Occlusal radiograph image receptor size in children

Answer 2

5x4cm

Question 3

Oblique occlusals indications (like large periodicals)

Answer 3

1. Periapical type assessment when periapicals not possible
2. Pathology too large to be seen on a periapical (oblique shows 4 anteriors periodical shows 3)
3. Trauma - fractures to teeth and alveolus

Question 4

What are dental alveoli?

Answer 4

Tooth sockets

Question 5

What type of radiograph would be used to view a supernumerary tooth?

Answer 5

Oblique occlusal

Question 6

What should the X-ray beam be perpendicular to?

Answer 6

Object plane + image receptor

Question 7

List some projection geometry issues (3)

Answer 7

1. Image receptor + object not in contact
2. Beam of X-rays not parallel
3. X-ray beam might not be perpendicular to object plane and image receptor

Question 8

List of some projection geometry solutions - Bisecting Angle Technique (3)

Answer 8

1. Image receptor + object partly in contact but not parallel
2. Image receptor + object close together at crowns but apart at apices

Question 9

Explain the bisecting angle technique

Answer 9

Image receptor and tooth touch at crown but apart at apex

Question 10

In the bisecting angle technique, what happens if the X-ray beam is at 90 degrees to long axis of the tooth?

Answer 10

Elongated image

Question 11

In the bisecting angle technique, what happens if the X-ray beam is at 90 degrees to the plane of the image receptor

Answer 11

Short image (foreshortened)

Question 12

If a pt has proclined incisors how must you adapt the vertical angle?

Answer 12

Increase it

Question 13

If a pt has retroclined incisors how must you adapt the vertical angle?

Answer 13

Decrease it

Question 14

What head position should the patient be in for an occlusal radiograph?

Answer 14

Sitting up

Question 15

How are head positions for radiographs altered?

Answer 15

By degree of mouth opening

Question 16

What position should the patients be in for a maxillary occlusal? (2)

Answer 16

MAXILLA:

• Ala-tragus line horizontal (parallel to floor)
• Upper teeth stable

Question 17

What does ala-tragus line mean?

Answer 17

Ala - nose

Tragus - ear (in front of external auditory meatus)

Question 18

What position should the patient be in for a mandibular occlusal? (3)

Answer 18

MANDIBLE:

• Corner of mouth-tragus line horizontal (parallel to floor)
• Teeth apart
• Head tilted back

Question 19

How are storage phosphor plates used?

Answer 19

• Go in between upper and lower teeth

- Held in place by biting (can be damaged)

Question 20

Why do storage phosphor plates have a plastic cover over them?

Answer 20

So the sensor itself doesn’t come into contact with saliva + protect from toothmarks

Question 21

Oblique occlusal guideline vertical angle:

UPPER ANTERIOR

Answer 21

60 degrees

Question 22

Oblique occlusal guideline vertical angle:

UPPER OCCLUSAL CENTRED ON CANINE

Answer 22

55 degrees

Question 23

Oblique occlusal guideline vertical angle:

UPPER OCCLUSAL CENTRED ON PREMOLAR

Answer 23

50 degrees

Question 24

Oblique occlusal guideline vertical angle:

UPPER OCCLUSAL CENTRED ON MOLAR

Answer 24

45 degrees

Question 25

Oblique occlusal guideline vertical angle:

LOWER ANTERIOR OCCLUSAL

Answer 25

40 degrees to occlusal plane

Question 26

Oblique occlusal guideline vertical angle:

LOWER OCCLUSAL CENTRED LATERALLY

Answer 26

35 to occlusal plane

Question 27

What does the orientation of the image receptor depend on? (2)

Answer 27

1. Size of mouth

2. Patient tolerance

Question 28

Mandibular true occlusal indications (NOT used often) (4)

Answer 28

1. Detection of submandibular duct calculi
2. Assessment of bucco-lingual position of un-erupted teeth **
3. Evaluation of pathological bunco-lingual expansion **
4. Horizontal displacement of fractures **

** = can use CBCT

Question 29

Why do we not use MAXILLARY true occlusals? (2)

Answer 29

• Can’t get X-ray source that close to maxilla

- Have to go through more dense boney structure

Question 30

What is the term for when a molar and premolar are facing each other very closely?

Answer 30

Kissing teeth

Question 31

What position should the patient be in for a mandibular true occlusal?

Answer 31

Head tipped as far back as comfortable