DPTs

Question 1

What are the difficulties in imaging the dental arches?

Answer 1

Curved object
Super-impostition of other structures
Individual occlusion and jaw shapes

Question 2

How are all angles of the jaw picture on a DPT?

Answer 2

3 points of rotation

Question 3

How long does it take a DPT to be taken?

Answer 3

20secs

Question 4

What is the first vertical line seen on a DPT above the teeth?

Answer 4

Posterior wall of maxillary sinus

Question 5

What is the difference between CBCT generated vs conventional DPT

Answer 5

CBCT much clearer because it is a 3d imagine device that can choose a very thin sample to picture

Question 6

Why are CBCT’s not used generally?

Answer 6

Very high radiation dose

Question 7

Why are full mouth periapicals not used?

Answer 7

Much higher radiation than DPT

Question 8

List 6 situations in which a DPT may be used?

Answer 8

Orthodontic assessment
Bony lesions
Pre-GA
Periodontal disease
Trauma
Pre-implantion 
3rd molar view
Cannot tolerate intra-oral views

Question 9

Where does the Frankfort plane run from?

Answer 9

Upper border of external auditory meatus to lower border of orbit

Question 10

What is the correct position of X-ray in terms of Frankfort plane?

Answer 10

Frankfort plane should be parallel to line of X-ray

Question 11

In what position should teeth be for DPT?

Answer 11

Slightly seperated

Question 12

What is the position problem if the image shows too much spine and the anterior teeth are thin and elongated?

Answer 12

Patient too close to the imagine machine

Question 13

What is the problem with positioning if the image shows magnified teeth and no spine?

Answer 13

Patient too far away from imaging machine

Question 14

In what position will a DPT lose the smile line?

Answer 14

Chin too far up and too far away

Question 15

What positioning problem will cause magnification of one side of the DPT?

Answer 15

Rotation

Question 16

What is a common ghost image seen on a DPT?

Answer 16

Opposite side of the mandible

Question 17

List the characteristics of chest images?

Answer 17

Located on opposite side than actual object
Same shape as actual object
Larger than image of actual object
Projected on higher film
Less distinct

Question 18

Why might a DPT of an edentulous jaw be helpful?

Answer 18

Good assessment of any retained roots and visualisation of ID canal (pressure on denture)

Question 19

What do multiple radiolucencies at roots suggest (when teeth are healthy)

Answer 19

Malignancy

Question 20

What should you do if a child has prematurely erupting teeth?

Answer 20

Red flag - malignancy