Laboratory Procedure

Question 1

Before the addition of blackout wax, maxillary master cast will be beaded, this is the outline of maxillary major
connector using round bur. The bead line run …

Answer 1

3-4 mm from gingival margin.
Beading is not done on mandibular major connector.

Question 2

Blockout techniques:

Answer 2

A- parallel blockout: Used to block out undercuts parallel to the path of insertion.
B- shaped blockout: The block out wax can be shaped with hand instruments to provide a slight ledge just
apical to clasp tip. This ledge guides the placement of wax pattern.

C- arbitrary blockout: area of undercut not involve in framework design

Question 3

*Relief:

Answer 3

thin layer of wax used to create smooth surface at area of relief.

Question 4

Areas need relief:

Answer 4

a- beneath mandibular major connector.
b- saddle in free end saddle to create space for attachment of acrylic to metal frame work.

Question 5

To make impression, the ……is placed on the base of a duplicating flask. The flask is
filled slowly with….

Answer 5

blockout master cast

hydrocolloid material

Question 6

Refractory cast:

Answer 6

Gypsum bonded investment is used for casting gold, while phosphate bonded investment is used for
chrome cobalt alloys.

Question 7

Bees wax dip:

Answer 7

To insure a smooth and dense surface on the refractory cast. The cast is dipped in hot bees wax.
Once the cast has cooled to room temperature, it is ready to be waxed.