Dental Material #7 – Unidontia

1. the effectiveness of condensation and prevention of porcelain shrinkage is determined by

thickness of platinum mix

speed of icrease of furnace heat

use of powder containing particles that are of same size

shape and size of particles

Question 1 of 20

2. Following is added to zinc polycarboxylate to improve its manageability:

Strontium fluoride

Stannous fluoride

Aluminium oxide

Magnesium oxide

Question 2 of 20

3. Dental porcelain is manufactured by a process known as

Fritting

Creaming and bisque bake

Devitrification

Crystallisation

Question 3 of 20

4. When using which impression material can you delay pouring up of the model for up to one week?

polysulfide

poly vinyl siloxane

reversible hydrocolloid

Polyether

Question 4 of 20

5. a thinner mix of gypsum bondeded investment will result in

produce a smoother casting

increases setting expansion

increases thermal expansion

decrease setting expansion

Question 5 of 20

6. heat energy required for vaporisation of liquid after boiling

latent heat of fusion

latent heat of vaporisation

latent heat of sublimation

melting temperature

Question 6 of 20

7. Continues use of vibrator during investing leads to?

Surface irregularities

Discoloration

Random nodule formation

Surface roughness

Question 7 of 20

8. for a successful metal ceramic restoration both the metal and porcelain must have closely matched

coefficient of thermal expansion

solidification shrinkage

specific gravity

compressive strength

Question 8 of 20

9. Polysulfide impression material should be:

poured within 1 hour

poured immediately

poured within 15 minutes

poured within 30 minutes

Question 9 of 20

10. Asbestos is used as a lining in a casting ring to

allow for expansion of the investment.

insulate against thermal conductivity

facilitate removal of the investment after casting.

prevent fracture of the investment during heating.

Question 10 of 20

11. Not associated with corrosion products in metal alloys

Chlorides

Sulphides

Carbonates

Oxides

Question 11 of 20

12. Principle hardener in gold alloy is

Zinc

Silver

Copper

Palladium

Question 12 of 20

13. nickel is added to wrought gold alloys as

balance of color

strengthener

age hardner

scavenger

Question 13 of 20

14. mercury disposal is done by

treatment with acid

deep burial

controlled combustion

safe collection and reuse

Question 14 of 20

15. Which material has least shelf life

Polyether

Condensation silicone

Addition silicone

Polysulphide

Question 15 of 20

16. What is the effect of addition of an accelerator or a retarder to a gypsum cast

No relation to compressive strength

The compressive strength decreases

The compressive strength increases

The compressive strength may increase or decrease depending upon the amount of the accelerator/retarder added

Question 16 of 20

17. the accuracy of the temperature of the casting furnace may be verified by

reading the pyrometer

using a thermometer

observing the color of the mold in shadow

using templates of chemicals that melt at a specific temperature

Question 17 of 20

18. Cerrobend alloy is

low fusing material for removing memory patterns

high fusing metal for removing memory patterns

low fusing metal for positioning or shielding stent

high fusing metal for positioning or shielding stent

Question 18 of 20

19. Nodule on the intaglio surface of a casting can be prevented by

Spraying a surfactant on the wax pattern before investing

Use of a vibrator during investing of the wax pattern

Use of die spacer

Wet the wax with water before investing

Question 19 of 20

20. carnauba wax is added to basic paraffin wax to

improve the smoothness in molding

decrease flow at mouth temp

render it resistant to cracking and flaking

ensure uniformity of batches

Question 20 of 20