Weiss: Investing and Casting

Question 1

_____ ______ at the cavosurface margin is critical to good periodontal health and caries prevention.

Answer 1

Margin Adaptation

Question 2

What should be done JUST PRIOR to investment?

Answer 2

Re-wax the margin area because wax is not dimensionally stable

Question 3

The wax pattern should be ______ mm occlusal to the margin

Answer 3

1 to 2 mm

Question 4

If internal defects (voids or folds) are noted, what must be done?

Answer 4

Re-wax

Question 5

If there are no internal defects and the margins are adapted, what should be done?

Answer 5

Reseat the pattern on the die and refine with nylon

Question 6

After margin adaptation and refinement, what must be done immediately in order to avoid distortion?

Answer 6

Sprue and Invest

Question 7

What are some important things to consider in the placement of the sprue?

Answer 7

1. Determine thickest portion of the pattern by holding it up to the light
2. Do not attach to a critical area of the pattern (contact)
3. Do not attach to functional cusps

Question 8

At what angle to the long axis of the preparation should the sprue be placed?

Answer 8

45 degrees

Question 9

How do you attach the sprue to the wax pattern?

Answer 9

sticky wax

Question 10

The sprue has been placed. To prepare the casting ring, a 90 mm strip of ___ ______ should be positioned a uniform ____mm from one end of the ring.

Answer 10

ring liner

2mm

Question 11

Why must the ring liner be placed a uniform 2 mm from one end of the casting ring?

Answer 11

To allow a little space for expansion

Question 12

Sprue length should not exceed ____mm.

Answer 12

6

Question 13

The wax pattern should be ____mm from the top of the casting ring.

Answer 13

6

Question 14

At what temperature should the water bath be set?

Answer 14

100 degrees F

Question 15

A 100 degree F water bath is used for which expansion technique?

Answer 15

Hygroscopic

Question 16

The wax pattern should be placed in the _____ _____ of the casting ring.

Answer 16

Heat Center

Question 17

Between the casting ring and the pattern there should be ______mm and between the heat center and the pattern should be _____mm.

Answer 17

6

6

Question 18

To what is the wax pattern attached?

Answer 18

Sprue Base

Question 19

Which occurs first, attachment to casting ring or attachment to sprue base?

Answer 19

The wax pattern is attached to the sprue base (sprue to dome). Then the casting ring is placed onto the base.

Question 20

What is used to decrease surface tension?

Answer 20

De-bubblizer (soap)

Question 21

Prior to investment, what must be wet?

Answer 21

All surfaces of the wax pattern AND the ring liner

Question 22

True or False: the vacuum mix is used during the investment technique.

Answer 22

True.
Vacuum mix for 20 seconds
2 minute work time…fill the casting ring

Question 23

Immediately upon filling the casting ring (with gypsum), where must it be placed? For how long?

Answer 23

Place IMMEDIATELY into 100 degree water bath

at least 30 mins. No longer than 3 hours.

Question 24

What are the two steps in the expansion?

Answer 24

Step 1: Setting expansion. Powder (gypsum) provides expansion by pushing apart the crystals. More POWDER = more expansion

Step 2: Hygroscopic expansion. Water feeds crystal growth. More TIME= more expansion

Question 25

During wax pattern elimination, what must be removed before placement in the burnout oven?

Answer 25

The sprue base must be removed from the casting ring

Question 26

Wax pattern elimination occurs in ___ steps and the temperature(s) of the oven(s) is(are):

Answer 26

two Step 1: oven temp = 200 degrees F Step 2: oven temp = 900 degrees F

Question 27

During wax pattern elimination, the mold should be placed in the oven with the sprue end ______.

Answer 27

Down

Question 28

How long must the mold remain in the Stage 1 furnace?

Answer 28

45 mins | at 200 degrees

Question 29

What is the temperature of the Stage II furnace?

Answer 29

900 degrees F

Question 30

What is done with the sprue after removal from the Stage I furnace?

Answer 30

Immediately it must be placed in the Stage II furnace with the sprue end down

Question 31

How long must the mold remain in the stage II furnace?

Answer 31

1 hour | at 900 degrees

Question 32

During the gold casting procedure, you will wind the arm of the casting machine ____ complete turns in a _____ direction. Then the arm is secured in position by engaging the _______ _____.

Answer 32

3 Clockwise Casting arm

Question 33

What are the four materials needed for the gold casting procedure?

Answer 33

1. Crucible 2. Gold Alloy 3. Cradle 4. Metal Tongs

Question 34

Which gold-casting item is placed on the platform of the casting machine? Which item is placed on the support pins?

Answer 34

Crucible | Cradle

Question 35

When adjusting the torch, the flame should reach ______ inches.

Answer 35

10 to 12

Question 36

What are the three areas within the torch flame? Which area is the correct portion for touching the gold?

Answer 36

Torch Flame = oxidizing area, reducing cone, oxidizing area | *The reducing should be touching the gold*

Question 37

The reducing cone of the torch flame should be held at what angle to the gold alloy?

Answer 37

45 degrees

Question 38

How long should the gold be heated within the reducing cone of the torch flame?

Answer 38

Until the gold coalesces into a sphere and the surface becomes shiny (appears to be spinning)

Question 39

True of False: When using the torch, the flame should be kept moving constantly.

Answer 39

True

Question 40

Before placing gold alloy into the crucible, the crucible should be _____.

Answer 40

Preheated

Question 41

How much gold-casting alloy is placed into the crucible?

Answer 41

8 pennyweight

Question 42

The casting arm is released by placing pressure in a ____direction.

Answer 42

Clockwise

Question 43

When should the casting ring be placed into cool water?

Answer 43

When the mold loses its glowing red color

Question 44

Placement of the casting ring into cool water causes the ____ to break away.

Answer 44

Investment

Question 45

When using previously cast gold, what should be the ratio of old to new?

Answer 45

50:50

Question 46

What is the last stage of the investing/casting procedure?

Answer 46

Removal of the sprue