Occlusal Radiology

Question 1

What are the diff types of occlusal radiographs you get?

Answer 1

• Oblique
• true (cross sectional)
• lower only

Question 2

What types of sensors are used in GDH

Answer 2

phosphor plates

Question 3

What are the indications for an oblique occlusal? (4)

Answer 3

• for a periapical type assessment where periapicals aren’t possible (e.g. trismus)
• Pathology too large to be seen on a single periapical (maybe CBCT now)
• Trauma (fractures to teeth and alveolus)
• Localisation using parallac (+ panoramic, other occlusal or periapical)

Question 4

Describe what the head position is when taking an oblique occlusal and what lines you check for this?

Answer 4

Tilt the head slightly forward (supported by head rest) Want the ala-tragus line and the occlusal plane to be parallel to the floor ( NOTE: patient is seated

Question 5

Where is the occlusal plane for the mandible?

Answer 5

From corner of the mouth the the tragus

Question 6

What is the head position for mandibular oblique occlusals?

Answer 6

Occlusal plane (corner of mouth to tragus) is parallel with the floor head will be tilted back

Question 7

What side of the phosphor plate is the active side?

Answer 7

The blue side/side without writing

Question 8

How is the phosphor plate placed into the plastic cover?

Answer 8

So the side with writing can be seen (clear side) and dot in the corner is inserted first (so will be at bottom)

Question 9

What is used to protect the x-ray packet/phosphor plates from damage?

Answer 9

Hinged carboard or plastic

Question 10

How is the x-ray packet placed into the patients mouth?

Answer 10

With the black side facing the x-ray source The dot is outside the patients mouth

Question 11

What will the patient be asked to do in order to keep the x-ray packet in place?

Answer 11

Bite gently (watch to ensure no chewing action)

Question 12

What should the horizontal angle to the teeth being examined be?

Answer 12

90 degrees

Question 13

What is a centring point?

Answer 13

Point where imaginary central ray is going to go in

Question 14

Where should the centring point for an oblique occlusal (maxilla) be?

Answer 14

1cm above the ala-tragus line

Question 15

How should the collimator of the x-ray machine be positioned to ensure the centring point is 1cm above the ala-tragus line?

Answer 15

Just above the bride of the nose

Question 16

Centring point for mandibular oblique occlusal?

Answer 16

Through the lower border of the mandible

Question 17

Centring point for a maxillary periapical?

Answer 17

On ala-tragus line

Question 18

Centring point for a mandibular periapical?

Answer 18

1cm above lower border of mandible

Question 19

What should the mid-sagittal line and the inter-papillary line be like when the patient is positioned correctly for maxillary oblique occlusals?

Answer 19

mid-sagittal = perpendicular to the floor inter-papillary = parallel to the floor

Question 20

The x-ray tube should have an approx vertical angulation of what?

Answer 20

60 degrees

Question 21

How should the vertical angulation change for proclined vs retroclined teeth?

Answer 21

Proclined = increase Retroclined = decrease

Question 22

Describe a true/cross-sectional occlusal radiograph?

Answer 22

-an occlusal size image receptor or periapical size -plan view when beam is through long-axis of a tooth

Question 23

What are the indications for a mandibular true occlusal?

Answer 23

• Detection of submandibular duct calculi • For assessment of bucco-lingual position of unerupted teeth ** • Evaluation of pathological bucco lingual expansion ** • Horizontal displacement of fractures ** ** = cone beam CT may be used nowadays if available

Question 24

How is the image receptor placed? (true occlusal)

Answer 24

-Transverse in occlusal plane or lengthwise over region of interest

Question 25

How is head placed and how is x-ray beam directed? (true occlusal)

Answer 25

-head tipped back as far as comfortable -x-ray beam directed at 90 degrees to image receptor in midline OR through region of interest