Lec 13: Laboratory Works

Question 1

• Withstand casting temperature
• Wax-up framework using design on secondary cast or paper equivalent.
• Prefabricated wax patterns

Answer 1

Refractory cast

Question 2

Purpose of duplicating master cast with refractory material?

Answer 2

To produce 2 casts:
a) Refractory cast = casting RPD frameworks
b) Duplicate master cast = seating RPD frameworks

Question 3

• Heat resistant duplicate of master cast
• Made from dental casting investment
• Act as base for forming RPD framework in wax and plastic

Answer 3

Refractory cast

Question 4

Scoring a cast with a sharp instrument or bur in any desired area to provide a seal between the finished prosthesis and soft tissue.

Answer 4

Beading

Question 5

A depression created along the borders of the framework drawn on the cast so resultant framework will have an elevation at its borders.

Answer 5

Beading

Question 6

In which cast/jaw do we do beading?

Answer 6

Maxillary cast (to get a good seal)

Question 7

Elimination of undesirable undercut areas on the cast to be used in the fabrication of RPD.

Answer 7

Blockout / Wax out

Question 8

3 types of blockouts

Answer 8

Parallel
Shaped
Arbitrary

Question 9

• Undercuts below the height of contour of the existing teeth are eliminated in relation to that path of insertion.
• Includes proximal tooth surfaces used as guiding planes and below height of contour.

Answer 9

Parallel blockout

Question 10

• Done in the undercut of the primary abutment along the lower border of the proposed retentive arm.
• On buccal and lingual surfaces to locate wax patterns for clasp arms.

Answer 10

Shape blockout

Question 11

• Filling the soft tissues and other unwanted undercuts in the cast.
• Eliminate undercuts in the ridge, soft tissues which may interfere with path of insertion.
• Need not be parallel to path of insertion.
• Labial surfaces and labial undercuts not involved in RPD design.

Answer 11

Arbitrary blockout

Question 12

• Procedure of placing a sheet of wax in strategic areas on the master cast to be duplicated so that a refractor cast can be made.
• To provide SPACE between certain components of framework and the adjacent oral structures (minor connector to which denture base will be attached).
• Adapting spaces will produce an elevation.

Answer 12

Relief / Relieving

Question 13

Placed on:
- Edentulous areas
- Beneath lingual bar connectors
- Areas in contact with thin tissues.

Answer 13

Relief / Relieving