Radiographic Techniques 2 - BW

Question 1

Why take BWs?

Answer 1

• detect caries
• monitor caries progression
• assess periodontal status
• assess existing restorations

Question 2

What is the difference between horizontal and vertical BWs?

Answer 2

Horizontal:

• usually one each side
• demonstrate distal of 4 to mesial of 8 unless otherwise requested
• centre of bite block on centre of 6
• demonstrate crowns and 1/3 root

Vertical:

• 2 each side
• demonstrate pre-molars and molars
• will demonstrate more of root but not apices

Question 3

What are the positioning requirements for a good bitewing?

Answer 3

• film and object parallel
• film close to object
• x-ray beam perpendicular to object and film
• always use a holder

Question 4

What are some common pitfalls in the horizontal plane?

When is horizontal overlap deemed acceptable?

What must be visible in BWs?

Answer 4

• having the film squint - not following dental arch on lingual aspect
• having the tube positioned incorrectly against the ring

Horizontal overlap is acceptable when less than half the enamel is superimposed, but theres a chance you will miss early carious enamel lesions

Must show the ADJ and the dentinal half of enamel

Difficult to avoid - crowding/tilting of teeth

Question 5

What is a common pitfall in the vertical plane?

What is the benefit of using a holder?

Answer 5

• failing to have the collimator touching all 4 corners of the aiming ring
• can cause vertical separation of cusp tips

Benefit of using a holder: allows you to keep source to object distance long and image receptor close to the object, thus reducing magnification

Question 6

Where does the orientation dot go for BWs?

PAs?

Answer 6

Bitewings: dot goes to palate

Periapicals: dot goes to crown