Investment Procedure

Question 1

Purppose of investment rings:

Answer 1

• to confine the investment at the end of the ring
• to decrease expansion in the longitudinal direction (most expansion occurs laterally)

Question 2

What is purpose of liners (in investment procedure)?

Answer 2

• to provide space for expansion of investment (soft, allows investment to expand laterally)

Question 3

Name the types of investment rings.

Answer 3

1. Solid metal ring
2. Three part split ring
3. Flexible rubber ring

Question 4

Preparation of investment ring?

Answer 4

• when solid metal ring is used, line it w wet liner
• liner shd fall slightly short of the ring

Question 5

Name the 3 investing techniques:

Answer 5

1. Hand investing (basically hand mixing)
2. Modified hand-investing (ring inverted => sprue base rests on bench)
3. Vacuum investing
   => minimise entrapment of air bubbles
   => better adaptation of investment of investment to wax pattern