11 Radiographic Techniques (3)

Question 1

Describe the basics of bisected angle technique

Answer 1

• film/image receptor is places as close to tooth as possible - without bending etc
• will usually contact crown but be distance from root apex
• long axis of tooth and film form an angle which is mentally bisected
• x-ray tube head is positioned so that beam is at 90 degrees to bisected plane
• overall length of image should be equal to length of tooth - law of similar triangles

Question 2

When would you utilise the bisected angle technique?

Answer 2

• to separate the roots of teeth
• to overcome superimposition
• when assessing root fractures
• when localising unerupted teeth
• when diagnosing apical pathology and the paralleling technique cannot be used
• when its okay to have a distorted view

Question 3

When would you request oblique occlusal radiographs?

Answer 3

• when a larger area is to be imaged than will fit on a periapical film
• some patients who retch
• children who cannot tolerate periapical views
• parallax views - to help assess the relative position of pathology or unerupted teeth

Question 4

what are the 3 mandibular occlusal views?

Answer 4

• lower 90degree occlusal (true occlusal)
• Anterior occlusal (45degree occlusal)
• oblique occlusal

Question 5

What is a mandibular true occlusal radiograph often taken to check for?

Answer 5

submandibular duct calculi

Question 6

What is meant by localisation?

Answer 6

Finding the exact position of a structure that cannot be seen clinically

Question 7

What are the indications for radiographic localisation?

Answer 7

• assessing buccal-palatal relationship of unerupted teeth to the dental arch
• position of foreign bodies
• expansion/destruction of bone
• position of salivary calculi
• separating the multiple roots of teeth for RCT
• assessing the displacement of fractures

Question 8

what are parallax views?

Answer 8

2 views/radiographs taken of same object with a change in angulation of beam