1.Fineness of the gold used for direct filling is;

A. 22 carats
B. 18 carats
C. 24 carats
D. 20 carats

Answer B

2.Cohesion of gold foil is an example of;

A. Atomic attraction and cold welding
B. Annealing
C. Welding
D. Adaptation

Answer A

3.Type of gold recommended in occlusal load bearing areas is;

A. Annealed gold
B. Gold foil
C. Matgold
D. Powdered gold

Answer C

Electrolytic precipitate mat gold

• Microcystalline gold powder formed electrolytic precipitation– also called crystalline, mat or sponge.
• Mat gold is electrolytically precipitated crystalline form that is sandwiched between sheets of gold foil and formed into strips.
• Alloyed electrolyte precipitate
  • • Granular gold alloyed with 0.1% calcium.
    • Calcium increases the strength.

4.Electroalloy is an alloy of;

A. Gold and platinum
B. Cobalt and chromium
C. Gold and calcium
D. Tin and chromium

Answer C

5.The calcium is added to direct filling gold to;

A. Increase the smoothness of gold
B. Increase the hardness and strength
C. Increase corrosion resistance
D. All of the above

Answer B

6. The pure form of gold used in dentistry is known as___________________?

A. Cohesive gold
B. Non cohesive gold
C. Class I casting gold
D. Class IV casting gold

Answer:A

• For cold – welding gold should have a clean surface free from impurities. Gold attract gases eg. Oxygen, to its surface and any adsorbed gas film prevents cohesion of individual increments of gold, during their compaction.
• Cohesive gold — manufacturer therefore supplies the gold essentially free of surface contaminants, and thus inherently cohesive.

7.Direct filling gold formed by electrolytic precipitation is called by all the terms EXCEPT______________?

A. Crystalline
B. Granular gold
C. Mat gold
D. Sponge gold

Answer :B

8.When Gold fused with porcelain is fired at very high temperature greenish discoloration of cervical margin is due to________________?

A. High firing temperature
B. Disintegration of opaque layer
C. Presence of copper
D. Formation of excess oxides

Answer :C

9. Average particle size of powdered gold is________________?

A. 10 um
B. 15 um
C. 30 um
D. 0.1 um

Answer:B
Granular (powdered gold )

• Fine powder is formed by chemical precipitation or atomizing the metal. Particle size —maximum 74 micrometer and average particle size is 15 micrometer.
• Foil forms an effective container for the powdered metal and forms pellets of 1- 2 mm in diameter

Each pellet contains ten times more more metal by volume than are comparable sized pellet of gold foil

10.The cohesive gold used as bulk filler is_____________?

A. Electra alloy
B. Mat gold
C. Spherical gold
D. Gold foll

Answer:B