Dental Materials Mcqs - Set 7

1)   Reduction in the fusion temperature of dental gold casting alloys is caused by presence of______________?

a. Platinum
b. Copper
c. Silver
d. Gold
Answer  Explanation 

ANSWER: Copper

Explanation:
No explanation is available for this question!


2)   Softening heat treatment of alloy increases_________________?

a. Tensile strength
b. Proportional limit
c. Ductility
d. Hardness
Answer  Explanation 

ANSWER: Ductility

Explanation:
No explanation is available for this question!


3)   The function of a sprue is to_______________?

a. Form an opening of molten metal to enter the mold
b. Help polish cast restorations
c. Eliminate air bubbles on the wax pattern
d. Reproduce fine detail
Answer  Explanation 

ANSWER: Form an opening of molten metal to enter the mold

Explanation:
No explanation is available for this question!


4)   Stabilization of stainless steel is achieved by adding____________?

a. Carbon
b. Chromium
c. Nickel
d. Titanium
Answer  Explanation 

ANSWER: Titanium

Explanation:
No explanation is available for this question!


5)   The yield strength of AUstenite (NiTi alloy) is______________?

a. 100 Mpa
b. 240 Mpa
c. 560 Mpa
d. 700 Mpa
Answer  Explanation 

ANSWER: 560 Mpa

Explanation:
No explanation is available for this question!


6)   A highly polished surface on a metallic dental restoration aids considerably in the prevention of the____________?

a. Dimensional change
b. Thermal conductivity
c. Warpage
d. Tarnish and corrosion
Answer  Explanation 

ANSWER: Tarnish and corrosion

Explanation:
No explanation is available for this question!


7)   Tublulence of molten gold is due to _____________?

a. Impurities in gold
b. Improper venting
c. A and B
d. None of the above
Answer  Explanation 

ANSWER: None of the above

Explanation:
No explanation is available for this question!


8)   In a patient with allergy to costume jewelry, which of the following is contraindicated______________?

a. High gold
b. Low gold
c. Palladium – Ag
d. Ni – Cr
Answer  Explanation 

ANSWER: Ni – Cr

Explanation:
No explanation is available for this question!


9)   Indium in metal alloys_______________?

a. Improve bonding
b. Harden the metal ceramic Ag-Pd alloy
c. Both A and B
d. None of the above
Answer  Explanation 

ANSWER: Both A and B

Explanation:
No explanation is available for this question!


10)   Mouth temperature waxes are_______________?

a. Iowa wax
b. Modeling wax
c. Green stick wax
d. None of the above
Answer  Explanation 

ANSWER: Iowa wax

Explanation:
No explanation is available for this question!


11)   Incomplete casting is the result of_____________?

a. More porous investment in the mould
b. Narrow sprue diameter
c. Hollow sprue pin
d. Large reservoir
Answer  Explanation 

ANSWER: Narrow sprue diameter

Explanation:
No explanation is available for this question!


12)   Glossy smooth margins of a casting are due to_____________?

a. Shrinkage of alloy on cooling
b. Investment breakdown
c. Incomplete wax elimination
d. Incomplete gas elimination
Answer  Explanation 

ANSWER: Incomplete wax elimination

Explanation:
No explanation is available for this question!


13)   Gypsum bonded investment should not be heated over______________?

a. 700°C
b. 1,300°C
c. 1,063°C
d. 900°C
Answer  Explanation 

ANSWER: 700°C

Explanation:
No explanation is available for this question!


14)   Cobalt-Chrominum alloys contains_______________?

a. 30% cobalt and 60% chrominum
b. 60% cobalt and 30% chrominum
c. 1% palladium
d. 20% gold
Answer  Explanation 

ANSWER: 60% cobalt and 30% chrominum

Explanation:
No explanation is available for this question!


15)   The most commonly used Titanium alloy for dental and medical purposes is________________?

a. Ti 6Al 4V
b. Ti 5Al 4V
c. Ti 5Al 5V
d. Ti 6Al 6V
Answer  Explanation 

ANSWER: Ti 6Al 4V

Explanation:
No explanation is available for this question!


16)   Wax pattern is ideally invested immediately to decrease the dimensional changes caused by_______________?

a. Decrease flow
b. Continuous expansion
c. Relaxation of the internal stresses
d. Water loss
Answer  Explanation 

ANSWER: Relaxation of the internal stresses

Explanation:
No explanation is available for this question!


17)   The maximum carbon content of steel used in dentistry is__________________?

a. 19%
b. 2%
c. 1.7%
d. 4%
Answer  Explanation 

ANSWER: 1.7%

Explanation:
No explanation is available for this question!


18)   Flux is used during casting to________________?

a. Remove the oxides formed on the gold alloy
b. Lower the melting point
c. Replace casting wax
d. Speed the burnout process
Answer  Explanation 

ANSWER: Remove the oxides formed on the gold alloy

Explanation:
No explanation is available for this question!


19)   Resistance to corrosion in a cobalt-chrome casting is due to presence of_______________?

a. High quality iron
b. Chrome
c. Cobalt
d. Nickel
Answer  Explanation 

ANSWER: Chrome

Explanation:
No explanation is available for this question!


20)   Which is the use of boxing an impression______________?

a. Ease of construction of denture
b. Preserving the sulci
c. Ease of pouring an impression
d. All of the above
Answer  Explanation 

ANSWER: Ease of pouring an impression

Explanation:
No explanation is available for this question!


21)   Gap between true end of casting ring and wax pattern should be______________?

a. ¼ inch
b. ½ inch
c. 3/8 inch
d. one inch
Answer  Explanation 

ANSWER: ¼ inch

Explanation:
No explanation is available for this question!


22)   Addition of large amounts of platinum to a casting gold alloy will________________?

a. Decrease its strength and ability to be hardened
b. Decrease its tarnish resistance
c. Increase its fusion temperature
d. Redden the alloy
Answer  Explanation 

ANSWER: Increase its fusion temperature

Explanation:
No explanation is available for this question!


23)   All of the following statements about cast cobalt alloy are true EXCEPT_____________?

a. They have a modulus of elasticity twice that of gold alloys
b. They are more rigid than gold alloys
c. They have higher ductility than gold alloys
d. They have a lower proportional limit than gold alloys
Answer  Explanation 

ANSWER: They have higher ductility than gold alloys

Explanation:
No explanation is available for this question!


24)   4th state of matter is______________?

a. Solid
b. Liquid
c. Gas
d. Colloid
Answer  Explanation 

ANSWER: Colloid

Explanation:
No explanation is available for this question!


25)   All of the following statements about an alginate impression are EXCEPT________________?

a. It should be rapidly displaced from the mouth
b. It may exhibit fluid exudates on the surface as a result of imbibition of water
c. It will take up water and expand if kept wet
d. It will shrink as a result of syneresis
Answer  Explanation 

ANSWER: It may exhibit fluid exudates on the surface as a result of imbibition of water

Explanation:
No explanation is available for this question!


26)   Type I and Type II zinc oxide impression paste differ with respect to_______________?

a. Their use
b. Their hardness after setting
c. Water content
d. Eugenol content
Answer  Explanation 

ANSWER: Their hardness after setting

Explanation:
No explanation is available for this question!


27)   The term given to the phenomenon of moisture absorption by an alginate impression in________________?

a. Imbibition
b. Syneresis
c. Hysteresis
d. Gelation
Answer  Explanation 

ANSWER: Imbibition

Explanation:
No explanation is available for this question!


28)   The impression with the least dimensional change upon disinfection is_______________?

a. Addition poly silicone
b. Agar-agar
c. Polysulphide
d. Polyether
Answer  Explanation 

ANSWER: Addition poly silicone

Explanation:
No explanation is available for this question!


29)   Palladium is added to polyvinyl siloxane to_____________?

a. Act as a scavenger
b. Helps as surfactant
c. Acts as plasticizer
d. Acts as a catalyst
Answer  Explanation 

ANSWER: Act as a scavenger

Explanation:
No explanation is available for this question!


30)   Immediate pouring of impressions is most critical in_____________?

a. Condensation polysillicon
b. Addition Polysilicon
c. Polyether
d. A and B
Answer  Explanation 

ANSWER: Condensation polysillicon

Explanation:
No explanation is available for this question!


31)   The impression material used to record the prepared areas on abutment teeth is______________?

a. High viscosity elastomeric impression material
b. Medium viscosity elastomeric impression material
c. Low viscosity elastomeric impression material
d. None of the above
Answer  Explanation 

ANSWER: Low viscosity elastomeric impression material

Explanation:
No explanation is available for this question!


32)   Alginate impression material is________________?

a. Non-elastic impression material
b. Thermoplastic impression material
c. More mucostatic than ZOE
d. Less mucostatic than ZOE
Answer  Explanation 

ANSWER: Less mucostatic than ZOE

Explanation:
No explanation is available for this question!


33)   Syringe material is______________?

a. High viscosity elastomer
b. Medium viscosity elastomer
c. Medium & low viscosity elastomer
d. Low viscosity elastomer
Answer  Explanation 

ANSWER: Low viscosity elastomer

Explanation:
No explanation is available for this question!


34)   The impression for a diagnostic cast of a partial edentulous mouth should be taken in_______________?

a. Impression wax
b. Modelling compound
c. Hydro-colloid
d. Hydro cal
Answer  Explanation 

ANSWER: Hydro-colloid

Explanation:
No explanation is available for this question!


35)   Agar impression materials differ from alginate impression materials in that the former sets by_______________?

a. Mechanical action of saliva
b. Physical change
c. Evolution
d. Chemical change
Answer  Explanation 

ANSWER: Physical change

Explanation:
No explanation is available for this question!


36)   Which material undergoes hysteresis ?

a. Irreversible hydrocolloid
b. Reversible hydrocolloid
c. Impression plaster
d. Metallic oxide paste
Answer  Explanation 

ANSWER: Reversible hydrocolloid

Explanation:
No explanation is available for this question!


37)   The setting time of irreversible hydrocolloids can be decreased by_____________?

a. Raising the temperature of water used for maxing
b. Using excess water for maxing
c. Lowering the temperature of water used for mixing
d. None of the above
Answer  Explanation 

ANSWER: Raising the temperature of water used for maxing

Explanation:
No explanation is available for this question!


38)   Rubber base impressions are poured immediately as they_______________?

a. Continue to polymerize
b. Become elastic
c. Show imbibition and syneresis
d. Show gelation
Answer  Explanation 

ANSWER: Continue to polymerize

Explanation:
No explanation is available for this question!


39)   The most mucostatic impression material is_______________?

a. Thin mix of plaster of paris
b. Zinc oxide eugenol impression paste
c. Free flowing wax
d. Reversible hydrocolloids
Answer  Explanation 

ANSWER: Thin mix of plaster of paris

Explanation:
No explanation is available for this question!


40)   The best way to remove a hydrocolloid impression from the patient’s mouth is____________?

a. Slight rocking of the impression to disengage it from the undercut
b. Wetting the periphery of the impression with moist cotton to break the peripheral seal
c. Sudden jerking of the impression to prevent tearing
d. Supporting the impression along with the tray to prevent disengaging of the tray alone
Answer  Explanation 

ANSWER: Sudden jerking of the impression to prevent tearing

Explanation:
No explanation is available for this question!