MCQs on Dental Materials : Amalgams Part 3

# A true eutectic alloy has melting point:
A. Above that of the low fusing metal
B. above the melting point of either metal
C. Below that of the high fusing metal
D. Below the melting point of either metal

# Creep value of which of the following is the highest ?
A. Low copper amalgam alloy
B. Admix alloy
C. Single composition alloys
D. Creep value of all the above mentioned alloys is same

# Advantages of minimum mercury technique or Eames technique is all except:
A. High strength
B. Sets quickly
C. Needs no squeezing of excess mercury
D. Greater plasticity and adapts well to cavity walls

# Amalgam achieves 70% of the strength by:
A. 2 hours
B. 4 hours
C. 8 hours
D. 16 hours

# The solid solution of silver and mercury is called:
A. gamma 1
B. gamma 2
C. beta 1
D. gamma

# Mercury is toxic because it:
A. complexes hemoglobin to form methemoglobin
B. inhibits hemoglobin synthesis, producing anemia
C. inhibits aerobic glycolysis
D. binds to sulfhydryl groups

# Once triturated, the dentqal amalgam should be condensed within:
A. 5 minutes
B. 6 minutes
C. 3 minutes
D. 15 minutes

# What fraction of inhaled mercury vapors is retained in the body?
A. 45-55%
B. 55-65%
C. 65-85%
D. More than 85%

# High strength amalgam is achieved by:
A. Maximum matrix amd minimum alloy phase
B. Minimum matrix and maximum alloy phase
C. Maximum matrix phase
D. Minimum alloy phase

# The effect of trituration on strength in an amalgam restoration depends on:
A. Amalgam alloy
B. Trituration time
C. Speed of amalgamator
D. All of the above

# Which of the following does not occur in high copper amalgam ?
A. Electrochemical corrosion
B. Chemical corrosion
C. Penetrating corrosion
D. Corrosion does not occur at all

# Decrease in creep occurs in:
A. Under trituration or over trituration of amalgam
B. Decrease with condensation pressure
C. Increase with condensation pressure
D. Cannot be predictable

# For dental amalgam, the elastic modulus and tensile strength is:
A. 40 Gpa and 60-100 Mpa
B. 21 Gpa and 27-55 Mpa
C. 350 Gpa and 10-120 Mpa
D. 360 Gpa and 125-130 Mpa

# Cavo surface angle for amlagam restoration is butt joint as:
A. it increases compressive and tensile strengths
B. it decreases compressive and increases tensile strength
C. it decreases both compressive and tensile strength
D. it increases compressive and decreases tensile strength

# Adequete mixing of mercury is indicated by :
A. Dry mix
B. Shiny mix
C. Short mixing time
D. None

# Which of the following are characteristic feature of high copper amalgam alloy?
A. Low compressive strength
B. High marginal breakdown
C. Less marginal breakdown
D. High creep

# Which is true regarding lathe cut silver alloy?
A. Requires least amount of mercury
B. Achieves lowest compressive strength at 1 hour
C. Has tensile strength both at 15 min and 7 days comparable to high copper unicompositional alloy
D. has low creep

# Coefficient of thermal expansion of amalgam is :
A. 6.6 ppm/K
B. 11.4 ppm/K
C. 14.0 ppm/K
D. 25.0 ppm/K

# Gallium and Indium added to amalgam replace:
A. Silver
B. Tin
C. Mercury
D. Zinc

# A patient who has had a recent amalgam filling in the upper teeth has a gold filling in the lower teeth, the patient complains of pain. The reason for this can be mainly:
A. Improper amalgam filling
B. Pulp exposure
C. Galvanism
D. None of the above

# Which one of the following is not an objective of trituration?
A. Remove oxides from powder particle surface
B. Keep the amount of gamma 1 or gamma 2 matrix crystals to maximum
C. Pulverize pellets into particles to aid in attack by mercury
D. Achieve a workable mass of amalgam in minimum time

# Outstanding clinical performance of dental amalgam restoration is related to its:
A. Compressive strength
B. Tensile strength
C. Corrosion resistance
D. High Creep

# Eames technique is ptherwise known as:
A. No squeeze cloth technique
B. Increasing dryness technique
C. Bloting mix
D. Mortar and pestle mix

# Discoloration of Ag containing alloy is due to : (Two answers correct)
A. Wet corrosion
B. Dry corrosion
C. Tarnish
D. Both Tarnish and corrosion