4.0 Dental materials Flashcards
(25 cards)
Which acts as a scavenger during casting, preventing oxidation and improves castability?
a. Copper
b. Platinum
c. Iridium
d. Zinc
d. Zinc
What is an organic liquid which is a phenol derivative which is a major component of oil cloves that has an antibacterial and obtundent effect on the pulp?
a. Polyacrylic
b. Phosphoric
c. Eugenol
d. Alcohol
c. Eugenol
The large size of the filler particle in composites results in a restoration that _.
a. Feels rough to the dental explorer and appears rough to the eye
b. Feels smooth to the dental explorer and appears rough to the eye
c. Feels rough to the dental explorer and appears smooth to the eye
d. Feels smooth to the dental explorer an appears smooth to the eye
a. Feels rough to the dental explorer and appears rough to the eye
Light cured composite resin cement is indicated for the cementation of
a. Porcelain / composite inlays and onlays
b. Porcelain / composite crowns
c. Laminate
d. Maryland bridge
c. Laminate
What kind of temporary cement inhibits the setting of the final composite resin cement?
a. Zinc oxide eugenol
b. Cavit
c. Calcium hydroxide
d. Zinc oxide with fatty acids
a. Zinc oxide eugenol
What happens to the surface hardness of gold foil during condensation?
a. Is increased
b. Is decreased
c. Remains unaltered
d. Either increases or decreases depending upon the size of condenser point used
e. Either increases or decreases depending upon the force applied to the condenser
a. Is increased
Dental wax patterns should be invested as soon as possible after fabrication in order to minimize change in shape caused by
a. Reduced flow
b. Drying-out of the wax
c. Relaxation of internal stress
d. Continued expansion of the wax
e. Increased flow
c. Relaxation of internal stress
Which of the following statements describe composite resins?
I. can be placed and finished at the same appointment.
II. They are more color stable than unfilled direct filling resins.
III. They They are similar to amalgam with respect to coefficient of thermal expansion.
IV. The finished surface tends to be somewhat rough
a. I, II
b. I, IV
c. I, III, IV
d. II, III
e. II, III, IV
f. All of the above
a. I, II
The chief clinical advantage of the improved zinc oxide-eugenol cements over zinc phosphate cement for cementation of cast restorations is
a. Lower solubility
b. Lower film thickness
c. Less pulpal irritation
d. Higher compressive strength
e. Adhesion to tooth substance
c. Less pulpal irritation
In porcelain-fused-to-metal restorations, the most commonly used alloys have a base of
a. Tin
b. Gold
c. Nickel
d. Silver
e. Platinum
f. Palladium
b. Gold
The thermal insulating capacity of a cement base is
principally related to:
I.Thickness of the base placed
II. Density of the base placed
III. Thermal conductivity of the set base
IV. Coefficient of thermal expansion of the set base
V. Powder/liquid ratio of the cement mix
a. I, II, III
b. I, II, IV
c. I, III, V
d. II, III, IV
e. II, III, V
d. II, III, IV
The catalyst composition of polysulfide that is responsible for giving a brownish color and foul odor is
a. Epoxyethane with crotonic acid
b. Silicone with chloroplatinic acid
c. Ethyl silicate with tin octoate
d. Lead dioxide with sulfur
d. Lead dioxide with sulfur
Glass ionomer and compomer cements are not recommended for all-ceramic restorations because of its _.
a. Fluoride release
b. Low compressive strength
c. Low tensile strength
d. Excessive hygroscopic expansion
c. Low tensile strength
The amount of plastic strain produced in the specimen at fracture is referred to as _.
a. Toughness
b. Ductility
c. Strength
d. Resilience
b. Ductility
Longer spatulation time of gypsum material will tend
to _.
a. Reduce setting time and reduce setting
expansion
b. Reduce setting time and increase setting
expansion
c. Increase setting time and increase setting
expansion
d. Increase setting time and reduce setting
expansion
b. Reduce setting time and increase setting expansion
Light cured glass ionomer cement or restoration is
also known as _.
a. Resin modified glass ionomer
b. Simply glass ionomer
c. Composite
d. Compomer
a. Resin modified glass ionomer
The setting time for polysulfide rubber impression material is accelerated by
a. A slow addition and mixing of the
accelerator paste
b. Increasing the amount of base material
used
c. Raising both temperature and humidity
d. Adding several drops of oleic acid
e. Decreasing the amount of base material
used
c. Raising both temperature and humidity
Which of the following ways is the cast-gold inlay superior to an amalgam restoration?
I. Better adaptation to cavity walls
II. Lower thermal conductivity
III. Better capacity to withstand masticatory forces
IV. More accurate positioning of contact areas
a. I, III
b. I, IV
c. II, IV
d. III, IV
e. All of the above
d. III, IV
Minute traces of which of the following will render a gold alloy brittle?
a. Zinc
b. Copper
c. Mercury
d. Palladium
c. Mercury
Which of the following factors would tend to favor
true adhesion of restorative materials to a tooth
surface?
I. Restorative material with a high capacity for water sorption
II. Little difference in the coefficient of thermal expansion between the tooth and restorative material
III. Clean tooth surface
IV. Tooth readily wetted by restorative material
a. I only
b. I, II
c. I, IV
d. I, II, IV
e. II, III, IV
e. II, III, IV
The most desirable finished surface for a composite resin can be provided by:
a. White stones
b. Aluminum oxide disks
c. Diamond finishing burs
d. Hand instruments
e. Carbide finishing burs
c. Diamond finishing burs
Creep of a metal indicates that a metal
a. Lacks edge strength
b. Has excessive flexibility
c. Has insufficient retention
d. Will deform under static load
e. Has insufficient crushing strength
d. Will deform under static load
When a liquid wets a solid completely, the contact angle between the liquid and the solid is _.
a. 0 degrees
b. 45 degrees
c. 90 degrees
d. 135 degrees
e. 32 degrees
a. 0 degrees
A restorative material that has a high proportional limit, compared with one with a lower proportional limit, invariably has
a. Greater ductility
b. Greater toughness
c. A higher modulus of elasticity
d. More resistance to permanent deformation
e. Less resistance to permanent deformation
d. More resistance to permanent deformation
