Ability of an orthodontic wire to spring back to its original shape is evaluated by_____________?
A. Brittleness
B. Resilience
C. Tensile strength
D. Toughness
Dental Materials
The point at which a stress of a material exhibits a specific limited deviation P is called_______________?
The point at which a stress of a material exhibits a specific limited deviation P is called_______________?
A. Proportional limit
B. Tensile strength
C. Ultimate strength
D. Yield strength
Compressive stress is computed by dividing the external force by the_______________?
Compressive stress is computed by dividing the external force by the_______________?
A. Area of the test specimen upon which the weight rests
B. Elasticity of the test specimen in strain
C. Length of the test specimen beneath the force
D. Strain of the test specimen per unit length
The proportional limit is defined as______________?
The proportional limit is defined as______________?
A. The maximum stress in a structure
B. The minimum force required to cause a structure to break
C. The maximum stress that can be induced without permanent deformation
D. The maximum elongation under tension that can be measured before failure
Stress in defined as_______________?
Stress in defined as_______________?
A. An applied load or force
B. A deformation resulting from an applied load
C. An external force opposing an applied load
D. An internal force opposing an applied load
Setting expansion is advantageous in__________________?
Setting expansion is advantageous in__________________?
A. Casts
B. Models
C. Investment
D. Dies
Back pressure porosity can be avoided by________________?
Back pressure porosity can be avoided by________________?
A. Using asbestos linear
B. Placing the sprue at least one quarter inch away form the end of casting ring
C. Preventing rapid heating the investment in burnout oven
D. Using a short and wide sprue
Which of the following zones is used for melting alloy during casting______________?
Which of the following zones is used for melting alloy during casting______________?
A. Reducing flame
B. Oxidizing flame
C. Green flame
D. All of the above
Cleaning of base metal alloy is done by______________?
Cleaning of base metal alloy is done by______________?
A. Warm HCI
B. Cold HF
C. Cold H2SO4
D. Sand blasting with aluminium oxide
Which one of the following is most elastic ?
Which one of the following is most elastic ?
A. a titanium
B. B titanium
C. Chrome-cobalt-nickel
D. Nickel-titanium