Biomaterial Yin Sithoen
1. Proportional limit is defined as :
The stress/strain ratio within the elastic limit in a structure
The maximum force required to cause a structure to break
The maximum stress that can be induced without permanent deformation
A deformation resulting from an applied load
2. Which of the following is a measure of resistance to fracture ?:
Hardness
Toughness
Brittleness
Springiness
3. Zinc oxide eugenal impression should be removed from oral cavity :
When it can be easily indented by a blunt instrument
When the material cannot be intended by a blunt instrument
When the material is glossy
Exactly after four minutes after kneading
4. Oil of clove is sometimes used in preference to eugenal in ZOE paste because :
It increases mixing property of paste and therefore improves impression recorded
Reduces burning sensation of paste
Has a better reaction with zinc oxide
To increase setting time
5. One of the following statements which one is incorrect regarding polyether :
The main chain of polyether consists of copolymer of ethylene oxide and tetrahydrofuran
The main chain consists of copolymer of methylene oxide and tetrahydrofuran
Aromatic sulfonate ester acts as a cross linking agent
The base paste consists of polyether polymer
6. Clinical significance of smear layer :
Bonded to tooth structure and prevents composite adhesion
Increases the bonding action of the bonding agent
Provides calcium for adhesion of composites
Improve the strength of the composite
7. The common characteristic for pit and fissure sealant composite resins, acrylic appliances and elastomeric impression materials is
All of them are polymers
All of them can be employed as anterior filling materials
All of them should be heated before using
All of them are a result of secondary reaction
8. A cavity varnish used for lining the preparation for a dental amalgam restoration will :
Provide thermal insulation
Provide electrical insulation
Reduce early marginal leakage tooth structure
Provide strength of amalgam
9. The noble or base metal alloys used for PFM should have the following requisite :
Should bond with dental porcelain
Coefficient of thermal expansion should not be compatible with porcelain
Its melting temperature should be low in comparison with firing temperature of porcelain
Should be brittle
10. Contamination of zinc-containing amalgam by moisture during triturating or condensation :
Has no appreciable effect on properties except to the susceptibility to tarnish
Results in a sharp decrease in flow
Results in a marked expansion
Increases the setting time
11. The restorative material used to restore a small portion of an anterior tooth should have which of the following properties ?
Esthetics
High strength
Amalgam
Ease of casting
12. An anterior fixed partial denture could have facings constructed of which of the following materials ?
Composite resin
Metal
Amalgam
Gold alloy
13. Which of the following sentences describes the construction of removable partial dentures ?
Artificial acrylic teeth are attached
They are attached to upper natural teeth with cements,
They are attached to lower natural teeth with cements,
They are attached to natural teeth with cements,
14. Which of these statements apply to the filler particles of composites ?
Microhybrid composites contain as much as 84% filler by weight.
Microfilled
Microfilled composites contain more filler than all-purpose composites.
All are correct
15. Which of the following initiator-accelerator systems is needed for a light-activated composite?
Diketone-amine
Peroxide-amine
Organic acid-peroxide
Organic acid-metal ion
16. Which of the following office conditions minimize the health hazard from spilled mercury ?
Amalgam scrap stored in a closed container
Floor carpeting
Wall carpeting
Baseboard heating
17. Which of the following represents the maximum safe concentration of mercury vapor in the breathing zone for a 40-hour workweek ?
0.05 mg Hg/m3 of air
30 ng Hg/m3 of air
100 ng Hg/m3 of air
All are corrects
18. Which one of the following phases in dental amalgam restoration is most prone to electrochemical corrosion ?
Sn-Hg
Cu-Sn
Ag-Su
Ag-Hg
19. Which one of the following phases in dental amalgam restoration has the best mechanical properties ?
Ag-Su
Cu-Sn
Sn-Hg
Ag-Hg
20. Which one of the following mixing methods permits the escape of dental amalgam mercury vapor ?
Mixing in a mortar and pestle
Proportioning mercury and alloy into a friction-fit capsule
Triturating precapsulated alloy and mercury
A cover over the mixing arms on a triturator
21. A small portion of an anterior tooth would most likely be restored with which of the following ?
Amalgam
Composite resin
Gold alloy
Porcelain
22. A portion of a posterior tooth that is subject to high biting forces would likely be restored with which of the following ?
Amalgam
Composite resin
Acrylic resin
Glass ionomer
23. A direct restorative material used frequently to restore a portion of a posterior tooth that is subject to large biting forces would possess which of the following properties ?
Esthetics
High strength
Ease of casting
Thermal insulation
24. A full crown on a maxillary anterior tooth may be restored with which of the following restorative materials ?
Ceramic
Gold alloys
Composite resin
Amalgam
25. An anterior fixed partial denture could have facings constructed of which of the following materials ?
Ceramic
Gold alloy
Silver alloys
Amalgam
26. Which of the following sentences describes the construction of removable partial dentures ?
They are removable and attached to teeth with clasps.h with cements,
They are removable and attached to teeth with clasps.
Carbone steal
Artificial waxes teeth are attached
27. Full denture bases are usually made from which of the following materials ?
Composite restorative resins
Gold alloys
Acrylic resin
Ceramic
29. Acrylic resins are used in which of the following ?
Posterior inlays
Denture bases
Ceramic ( porcelain )-fused-to-metal crowns
Anterior onlays
30. Which of the following materials are used for dental implants ?
Gold alloys
Cobalt and chromium alloys
Titanium
Metal alloys
31. Which of the following statements about curing of composites are true ?
Exposure times of 2 to 3 seconds are needed for polymerization with visible light.
Before light activation, the base and catalyst pastes are mixed.
Lights with both blue and red wavelengths are equally effective for polymerization.
Light from an argon laser will activate polymerization.
32. Which of the composites with the following fillers may be radiopaque ?
Quartz
Lithium aluminum silicate
Colloidal silica
Barium glass
33. Which of the following polymer systems are used for the organic matrix in composites ?
Bisphenol A-glycidyl methacrylate (Bis-GMA)
Poly (methyl methacrylate)
Polystyrene
Pheyl methacrylate
34. Which of the following properties are higher for microhybrid composites than for microfilled composites
Polymerization shrinkage
Thermal expansion
Water sorption
Modulus of elasticity
35. Which of the following is the best choice of restorative material to achieve moderate to high strength, fluorite release, and esthetics ?
Composite
Compomer
Hybrid ionomer
Glass ionomer
36. Which of the following statements about laboratory composites are true ?
Curing using light, heat, and pressure increase the wear resistance.
Bridge prepared from laboratory composites require a metal substructure.
Fiber reinforcement increases their strength but decrease their rigidity.
Restorations prepared from laboratory composites typically are cemented with zinc phosphate cement.
37. Which of the following statements about adhesion of composite restorations to tooth structure are true
Bonding is achieved to enamel by application of an acid etchant followed by application of a bonding agent and then the composites resin.
The bonding agent forms a hybrid layer with enamel.
The bonding agent forms a micromechanical bond with enamel but a chemical bond with dentin.
Most bonding agent bond more effectively to a dry tooth surface.
38. Which of the following statements about compomers are true ?
They are two-paste systems that self-cure within 2 to 3 minutes.
Because of their resin content, they require a bonding agent for adhesion to tooth structure.
They typically are recommended for class II restorations.
They also are know as GIC
39. Which of the following statements apply to the packable composites ?
Their depth of cure allows bulk polymerization, which has been shown to be clinically effective.
Their wear rate is low (3.5 µm/year). Which is similar to that of amalgam.
They are radiolucent.
Radiopaque
40. Which one of the following office conditions minimize the health hazard from spilled mercury ?
Baseboard heating
Floor carpeting
fluorite release
Amalgam scrap stored in a closed container
41. Which one of the following represents the maximum safe concentration of mercury vapor in the breathing zone for a 40-hour work week ?
0.04 mg Hg/m3 of air
30 mg Hg/m3 of air
100 mg Hg/m3 of air
0.05 mg Hg/m3 of air
42. Once amalgamation has occurred, which of the following is true of mercury ?
Is combined primarily with silver
Has the toxic properties of unreacted mercury
Can form at the surface of amalgam restorations if heated to 0° C
Composite restorative resins
43. For each property, list the amalgam type (irregular low-copper, admixed high-copper, and spherical high-copper ) that has the highest value?.
1-hour compressive strength spherical high-copper
Tensile strength spherical high-copper
Creep irregular low-copper
Creep irregular high-copper
44. Which of these statements are correct in terms of preparing a correctly triturated mass of amalgam ?
An undertriturated mass is crumbly and dull.
A correctly triturated mass is a smooth homogeneous, and dull.
An overmixed mass is removed readily from the capsule but is soupy in appearance.
Dental amalgam is a mixture of silver alloys and mercury.
45. Which statements are true for bonding of amalgam to tooth structure ?
The most effective bonding agents contain copalite.
Shear bond strength using amalgam bonding to teeth in clinically proven to be as high as that for bonding composites to teeth.
The use of amalgam bonding restores the strength of the clinical crown to its original condition.
The use of amalgam bonding reduces marginal leakage of amalgam restorations.
46. Which of the following phases in dental amalgam restoration is most prone to electrochemical properties ?
Ag-Sn
Cu-Sn
Sn-Hg
Ag-Hg
47. Which of the following phases in dental amalgam restoration has the best mechanical properties ?
Ag-Sn
Cu-Sn
Sn-Hg
Ag-Hg
48. Which of the following mixing methods permits the escape of dental amalgam mercury vapor ?
Mixing in a mortar and pestle
Proportioning mercury and alloy into a friction-fit capsule
Triturating precapsulated alloy and mercury
A cover over the mixing arms on a triturator
49. Which one of the following is not true about high-copper dental amalgam restorations ?
Contain both Sn and Ag in the composition as well dental amalgams
Contain both Sn and Ag in the composition as well
Produce excessive creep
Restorations are more brittle than low-copper versions
50. Which one of the following is not a criterion for a failed high-copper dental amalgam restorations ?
Creep of the restoration out of the cavity preparation in proximal areasng occlusal margins
Creep of the restoration out of the cavity preparation in proximal areas
Wear facets along the occlusal contach areas
Micrographs of alloys particles.
51. Dental personnel can do which one of the following to limit their exposure to mercury ?
Sterilize amalgam scrap
Vacuum up a spill immediately
Avoid touching freshly mixed amalgam
Avoid polishing amalgams
52. The primary difference between low- and high-copper amalgams is which of the following ?
The amount of copper
The amount of copper and zinc
The amount of copper and tin
The amount of copper and silver
53. Ideally, the set amalgam should do which of the following ?
Expand greatly to provide marginal seal against the tooth
Shrink significantly to provide space for correction products to seal the margins
Have little dimensional change
Properties of amalgam
54. The physical properties most desirable in set amalgam are which of the following ?
Higher strength, low creep, low corrosion
Low strength, low creep, low corrosion
Higher strength, high creep, low corrosion
Higher strength, high creep, high corrosion
55. Higher mercury left in an amalgam leads to which of the following ?
Higher creep
Higher strength
Low corrosion
High corrosion
56. Which of the following occurs when dental amalgam is overmixed ?
Compressive strength decreases
Corrosion decreases
Tensile strength increases
Corrosion increases
57. The physical property measured in terms of the deformation of the structure per until dimensions is ?
Stress
Strain
Space lattice
Amorphous material
60. Crystalline materials have :?
No space lattice
Less stable space lattice
Well-defined melting
No well-defined melting
61. Materials having coefficient of thermal expansion close to the tooth structure :?
Unfilled
Silicate cement
Glass ionomer cement
Amalgam
62. The temperature at which a solid changes into liquid is called :?
Temperature of vaporization
Fusion temperature
Specific temperature
Latent heat
63. Strain that occurs when the material is stressed to its proportional limit is called :?
Resilience
Flexibility
Modulus of elasticity
Toughness
64. Which of the following uses a hardened steel ball indenting tool ?
Rockwell hardness test
Vichers hardness test
Brinell hardness test
Knoop hardness test
65. A measure of ductility of a material is referred to as :?
Proportional limit
Percentage elongation
Flexibility
Yield strength
66. The energy absorbed by a material when it is stressed to its proportional limit is :?
Impact strength
Toughness
Resilience
Flexibility
67. The strain at which the plastic strain develops may be represented by :?
Elastic limit, modulus of elasticity, tensile strength
Elastic limit, yield strength, proportional limit
Yield strength, tensile strength, toughness
Toughness, rigidity, resilience
68. The tendency of stainless steel to break under repeated condition of cyclic stressing below the ultimate strength is :?
Resilience
Fatigue
Creep
Ductility
69. Thermal conductivity is proportional to :?
Area of conduction
Hardness of metal
Fusion temperature
Type of metal
70. Which of the following is a measure of resistance to fracture ?
Hardness
Toughness
Brittleness
Springiness
71. Regarding Knoop hardness number, which of the following material is closest to that of dentine (KHN 65) ?
Amalgam
Pure gold
Composites
Silicates
73. Which of the following material has a high coefficient of thermal expansion ?
Silicate cement
Unfilled acrylic resin
Glass ionomer cement
Composite resin
75. Side effects and complications resulting from treatment by a physician or dentist is :?
Iatrogenesis
Teratogenesis
Calcium anhydrate
Calcium phosphate
77. Modifiers are added to plaster of Paris mainly to :?
Increase strength
Get a smooth surface
Reduce porosity
Regulate the setting time
79. Setting of plaster of Paris is a result of :?
Solubility difference between hemihydrates and dehydrate
Interaction between hemihydrates and water
Loss of water from hemihydrates
Indirect interaction between hemihydrates
81. Binder in the phosphate investment is :?
Cristobalite
Magnesium oxide and monoammonium phosphate
Manganese dioxide
Phosphoric acid
82. Potato starch is contained in which impression material ?
Impression compound
Agar agar
Impression plaster
Potassium sulfate
83. Commonly used coloring agent in impression plaster is :?
Congo red
Indigo dye
Alizarin red
Metallic oxide
84. Impression plaster is a :?
Mucocompressive material
Thermoplastic material
Mucostatic material
Reversible impression material
86. Impression compound is characterized by :?
Crystalline in nature with definite melting point
Amorphous in nature with high thermal conductivity
Amorphous in nature with low thermal conductivity
Crystalline in nature with high thermal conductivity
87. Following are the functions of impression compound except :?
To make impression of edentulous ridge
To make individual die impression with copper band
To make special tray for final impression
To record mucostatic impressions
88. Stearic acid in impression compound :?
Reduces plasticity
Reduces brittleness
Reduces flow
Increase setting time
89. Most common use of Zinc oxide eugenol paste :?
Wash impression for edentulous patients
Dual impression for Partially edentulous patients
As interocclusal record material
Surgical paste
90. Greater ratio fo zinc oxide to eugenol will have the following effect on setting time :?
Decreases setting time
Increases setting time
Does not alter setting time
Depends on rate of mixing
91. Which of the following properties would be of least importance, when selecting an impression material ?
Dimensional stability
Biocompatibility
Flow
Adhesion
92. The gelation temperature of agar hydrocolloid impression material should be :?
Far below the oral temperature
37-450C
100C higher than mouth temperature
45-600C
93. Pick out the incorrect statement regarding alginate impressions :?
May exhibit a fluid exudates on the surface as a result of imbibitions
Will be shrink as a result of syneresis
Will take up water and expand if kept wet
Is an irreversible hydrocolloid impression material
94. Alginate impression material deteriorates rapidly at :?
Normal room temperature
Elevated temperature
Low temperature
Temperature does not cause any change in shelf-life
95. Hydrocolloid impression should be removed from the mouth with a sharp jerk because :?
It is the easiest method of removal
Faster rate of removal increases the yield strength
It decreases the time for syneresis to occur
The brush heap structure of a gel responds more favorably to a sudden force
96. Thickness of the gel between the tray and tissue for either agar or alginate should always be at least :?
1 mm
2 mm
3 mm
4 mm
97. Setting time of alginate can be better controlled by :?
Mixing time
Temperature of water used of mixing
Changing water: powder ratiocelerators and retarders
Changing water: powder ratio
98. In alginate impression the final gel is :?
Sodium sulphate
Calcium sulphate
Sodium alginate
Calcium alginate
99. Oxalates, carbonates, potassium, trisodium phosphates are added to alginate as :?
Accelerators
Retarders
Reactors
Fillers
100. Main disadvantage of laminate technique of making impression is : ?
Bond between agar and alginate is not very strong
Maximum details are not produced
Cost factor is high
Difficult to manipulate
101. Which of the following is recommended as an adhesive to trays with polysulfides ?
Polydimethyl siloxane
Styrene-acrylonitrile
Ethyl silicate
Acrylic resin
102. Which has the highest viscoelastic property and requires more time to recover from deformation ?
Condensation silicone
Polysulfide
Polyether
Addition silicone
104. The most accurate polysulfide impressions are made by using a custom acrylic tray because :?
Custom tray made of plastic material ensures a uniform thickness of impression material
It can hold more amount of impression material
More pressure can be applied during impression making
The tray does not distort during impression making
105. The byproduct in condensation silicones is :?
Ethyl alcohol
Methyl alcohol
Propyl alcohol
Butyl alcohol
106. The greatest amount of dimensional change after setting is exhibited by :?
Polysulfides
Condensation silicones
Addition silicones
Polyether
107. The catalyst used for condensation silicones is :?
Lead dioxide
Oleic acid
Stannous octoate
Platinum
108. The impression material which is routinely used in auto mixing devicee system is :?
Polyvinyl siloxane
Polyether
Polysulfied
Condensation silicone
109. Which of the following elastomers is suited for multiple cast pouring :?
Polysulfide
Condensation silicone
Addition silicone
Polyether
110. One of the following statements which one is incorrect regarding addition silicones :?
No evolution of any byproduct under all circumstances
Undetectable distortion on removal
Dimensionally stable even after 1 week
Can be used in automixing devices
111. Sulfur contamination from natural latex gloves inhibits the setting of :?
Alginate
Polyether
Polyvinyl siloxane
Zinc oxide eugenol impression paste
112. When a mechanical device is used for mixing addition silicones :?
There is no greater uniformity in proportioning and mixing
More possibilities of contamination
Mixing time is reduced
Mixing time is long
113. Distortion on removal from undercuts in addition silicones is very less due to :?
Stiffness of the material
Increased strain rate on unset material
Lowest strain in compression
Lowest strain in compression
Shrinkage of material
114. Polyether is different from other elastomers in the following aspects :?
Low stiffness
Hydropholic in nature
Can not be used as light cure material
High stiffiness
115. Stiffness of the material with passage of time is maximum in :?
Polysulfides
Polyether
Condensation silicones
Addition silicones
116. Hypersensitivity reactions like contact dermatitis is caused by :?
Polysulfides
Condensation silicones
Addition silicones
Polyether
119. The function of gum dammar in inlay wax is :?
No resistance to carving
No smoothness of pattern
Less strength to wax
To improve smoothness of pattern
120. Carnauba wax is preferred to candelilla wax as :?
It is harder and has less flow
It has low melting temperature
It provides luster to the pattern
It is sticky
121. Which of the following waxes used to align of castings before soldering ?
Sticky wax
Carding wax
Utility wax
Base plate wax
122. Which of the following is called periphery wax ?
Sticky wax
Bite registration wax
Utility wax
Beading wax
123. Which of the following is used to alter contour of impression trays ?
Utility wax
Carding wax
Beading wax
Boxing wax
124. Which of the following waxes is obtained from distillation of petroleum ?
Paraffin and microcrystalline wax
Carnauba and candellia
Montan and Japan coco
Spermitic and bees wax
125. Montan waxes have the following properties except :?
Obtained by extraction from lignite
Are mineral waxes
Have low melting points of 42oC
Hard, brittle and lustrous
126. The appropriate proportion of polymer to monomer component of dental resin by volume is generally :?
3:1
2:1
1:2
1:3
128. Porosity in denture base resins can be due to :?
Excess heating of resin above its boiling point
Adequate mixing of liquid and powder components
Well flasking of wax patternessure during polymerization
Well flasking of wax pattern
129. Main disadvantage of denture base soft reliner is :?
It has not to be changed over a period of time
It can be cleaned properly
It can not lead to fungal growth
It can not lead to cleaned property
131. Color stability of cold-cured resins is inferior to that of heat cured resins due to :?
Increased solubility of the resin
Subsequent oxidation of the tertiary amine
Variation in the molecular weight of the resin (low mol wt)
Decreased polymerization of the resin
132. Property which distinguishes composites from filled acrylic resins :?
Adhesive bonding between matrix and filler
Bonding with tooth structure
Bonding between coupling agent and filler
Bonding between coupling agent and tooth structure
133. Bis-GMA is a reaction product of :?
Bis-phenol-A and methyl methacrylate
Bis-phenol-A and glycidyl methacrylate
Bis-phenol-A and urethane dimethacrylate
Urethane dimethacrylate and glycidyl
135. Inorganic phase in a composite matrix :?
Decreases the mechanical strength
Increases coefficient of thermal expansion
Increases the mechanical strengthe polymerization shrinkage
Increases the mechanical strength
136. Commonly used viscosity controller in composites is :?
Bis-GAM
TEG-DMA
Polyurethanes
Methyl methacrylate
137. Which of the following composites give rough surfaced finish ?
Conventional composites
Microfilled composites
Hybrid composites
Small particle filled composites
138. The main advantage of composites compared to silicates cement is :?
Practically insoluble in oral fluids
Color matching with the tooth structure is excellent
High modulus of resilience
Coefficient of thermal expansion close to tooth structure
139. In visible light-cured composites photo initiator molecule is :?
Toluidine
Benzoyl methyl ether
Camphoroquinone
Bis-phenol-A
141. Which of the following composite is recommended for non stress bearing anterior restoration ?
Microfilled composites
Hybrid composites
Conventional composites
Small particles
142. The light-cured restorative resins have advantages over chemically activated restorative resins as :?
It has not more working time available
It takes more time for curing
It is more sensitive to oxygen inhibitors
It has more working time available
143. One of the disadvantages of using quartz as filler in restorative resin is :?
It cannot be polished
It cause abrasion and wearing of opposing tooth surface
It cannot be reduced to the size of microparticle composite
It has low affinity for resin matrix
144. The main resin constituent of polishable composite resin is :?
Polymethyl methacrylate
Polycaronate
Cyanoacrylate
Urethane dimethacrylate
145. In UV curing system the activator employed is :?
Benzoin methyl ether
Methyl methacrylate
Hydroquinone
Dibutyl phthalate
146. Light source in the curing unit is usually :?
Ultraviolet light bulb
Infra red bulb
Tungsten halogen light bulb
Sun light
147. Most commonly used pit and fissure sealant is :?
Unfilled acrylic
Polyurethane
Bis-GMA resin
Filled acrylic
148. Adhesion in composites is due to :?
Cohesion
True chemical bonding to tooth structure
Mechanical interlocking
Presence of smear layer
149. Dispensing composite resins using a syringe is advantageous because it :?
Increases strength and abrasive resistance
Increases surface smoothness
Conserves the material
Decreases air voids in the restoration
150. The light from the visible light curing unit can cause :?
Iritis
Cataract
Retinal damage
Corneal ulceration
151. In deep caities, the resin which remains unpolymerized can cause :?
Pulp inflammation
Sagging of restoration
Porosity in restoration
Secondary caries
152. In the cavities which are more than 2mm deep a light-cured restoration is :?
Not indicated
Cured for longer period
Restoration should be build in increments
Fifth generation bonding agent should be applied
153. If the light cure resin is curd in increments, it helps in :?
Compensating polymerization shrinkage
Providing strength to the restoration
Achieving complete polymerization
Saving the application of bonding agent
154. Chemically cured resin shrinks:?
Towards the center of bulk of material
Away from the light source
On the surface only
On the base only
155. A glaze is placed over the finished composite restoration to :?
No provide a better peripheral seal
To reduce surface porosities
Create a rough surface that is less receptive to extrinsic stain and plaque retention
To change the shade
156. Excess composite from the labial surfaces can be removed by using :?
Diamond burs at high speed
Diamond burs at low to medium speed
Carbide burs at high speed
Carbide burs at low to medium speed
157. Hand instruments for composites are made of :?
Stainless steel
Teflon-coated metal
Carbon steel
Titanium
158. Which of the following base is contraindicated for composites ?
Zinc phosphate
Zinc oxide eugenol
Calcium hydroxide
Glass ionomer cement
159. Which of the following statements is true regarding zinc phosphate cement ?
The least irritant to the pulp
Has an obtudant effect on the pulp
Is used as a permanent restorative material in adults
Is the oldest luting agent
160. Glass ionomer cenment is not recommended for :?
Class V restoration
Class III restoration
Class IV resoration
Class I restoration
161. The cavity for a GIC restoration is preconditioned with :?
Polyacrylic acid for 60 seconds
Polyacrylic acid for 10 seconds
Phosphoric acid for 60 seconds
Phosphoric acid for 10 seconds
162. The fluoride release from glass ionomer cement is :?
0.75 mg during the first week
0.075 mg during the first month
0.005 mg during the first week
0.0005 mg during the first month
163. Proconditioning before GIC restoration is done in order to :?
Create tags
Facilitate mechanical bonding
Remove smear layer
Provide more strenght
164. The main use of zinc oxide eugenol cement is :?
Permanent restoration
Temporary restoration
Base
Indirect pulp capping agent
165. The reason zinc oxide eugenol cement is used as a temporary restoration :?
It has an obtudant effect
It does not form reparative dentin
It has poor tensile strength
It does not have anticariogenic activity
166. The most effective cement in stimulating tertiary dentin is :?
Zinc phosphate
Calcum hydroxide
Zinc silicophoshpate
Polycardoxylate
167. Which of the following properties of calcium hydroxide cement help in the formation of reparative dentin ?
Low alkalinity
No antibacterial action
No Protein lysing effect
High alkalinity
168. Calcium hydroxide is used for :?
Pulp capping
Reduce maginal leakage
Reinforce the restoration
To prevent recurrent caries
170. For luting purpose, the film thickness should be :?
25 µm or less
minimum 50 µm
up to 75 µm
ideally 100 µm
171. Cavity varnish should not be applied when the following is used as a filling material :?
Amalgam
Silicate
Zinc phosphate
Direct resin-filling material
173. The desirable quality of porcelain is :?
Translucency
Thermal expansion
Toughness without brittleness
Requirement of color
174. Strength of dental porcelain is dependent on :?
No internal structure
Rough
Composition
Resistance to fusion
Resistance to fusion
175. Ideal method firing of porcelain is by using :?
Shorter firing at higher temperatures
Longer firing at low temperatures
Longer firing at high temperatures
Shorter firing at low temperatures
176. The following statements about dental porcelains are true except :?
It is brittle in nature
Undergoes firing shrinkage
Undergoes discoloration
Crystalline nature
177. In dental porcelains metallic oxides provide :?
Color and increases the strength
Color but decreases the strength
Color and provides refractile property
Provides refractile property and increases strength
178. Porcelain denture teeth :?
Are easy to grind and polish
Are more resistant of abrasion than gold
Have decreased abrasion resistance than dentin
Have higher coefficient of thermal expansion than resin teeth
179. In a porcelain fused to metal restoration, the porcelain is-bonded to metal by :?
Chemical bonding
Hight ductility of metal
Chemico-mechenical bonding
High malleafility of metal
180. The cracks formed on the ceramic during cooling because :?
The outer layer cools more rapidly than the interior
The cooling of the outer and the inner layer occurs at the same ratepidly than the outer layer
The cooling of the outer and the inner layer occurs at the same rate
Due to external forces
181. Condensation of porcelain is done by all the methods except :?
Spatulation method
Vibration method
Brush addition technique
Ceramming method
182. In a porcelain fused to metal restoration, when the coefficient of thermal expansion of metal and porcelain are different :?
Porcelain will crack on cooling
Porcelain will not bond with metal
Porcelain will wear off
Porcelain will provide good shade
183. Wet porcelain is condensed properly before firing to enhance all the properties except : ?
Reduce firing shrinkage
Reduce brittleness
Reduce porosity
increase strength
184. Which of the following components acts as a refractory material in porcelain ?
Feldspar
Potash
Kaolin
Silica
185. Porcelain-bonded to metal is stronger when fired :?
Under compression
Several times in air
After metal is tempered
Under low temperature
186. Metal has the following properties except :?
Metal is any element that ionizes positively in solution
All metals do not have same degrees of strength and plasticity
Pure metals are not useful in dentistry
Electroplated silver and copper are used in dies
188. The temperature at which a solid changes to liquid is known as its :?
Vapor temperature
Heat temperature
Fusion temperature
Temperature of specificity
189. Gold casting alloys are classified as type I, II, III or IV among these, having highest hardness is :?
Type I
Type II
Type III
Type IV
190. Of the four types of gold casting alloys, the most commonly used for crowns and bridges is :?
Type I
Type II
Type III
Type IV
191. Nickel sensitivity in the general population is :?
3% for men
3% for women
11% for women
1% in the overall population
193. When the gold content of gold alloys increases :?
The corrosion resistance increases
The percentage elongation decrease
The hardness decrease
Ductility decrease
194. Gold with high percentage elongation is best for :?
Increase the bond strength
To remove metallic oxide
To improve the castability
To revert sagging during firing
195. Passiveness of chrome cobalt alloys is due to formation of :?
Chromium carbide
Ferric oxide
Cobalt oxide
Chromium oxide
196. Silver has all the following characteristics except :?
Silver in pure form is not used in dental restorations
Addition of palladium to silver increases corrosion
Whitens when added to alloys
Silver points serve as a root canal filling material
197. Spot out incorrect statement regarding zinc in dentistry :?
Pure zinc has no application in dentistry
It is low in strengthely soft and ductile
It does not oxidize
199. All of the following are properties of Co-Cr-Ni wires except :?
They can be heat treated
They have excellent tarnish and corrosion resistance
They cannot be soldered or welded
Their hardness is comparable to stainless steel
200. Noble metal alloys are classified according to their :?
Melting temperature
Malleability
Castability
Dental function
201. Nickel in base metal alloys increase its :?
Strength
Hardness and fusion temperature
Modulus of elasticity
S Ductility
203. Elgiloy arch wire is :?
Cobalt-chromium-nickel alloy
Gold alloy
β-titanium arch wirere
β-titanium arch wire
204. Wrought metal :?
Cannot be rendered corrosion resistant
Can be formed by pouring molten metal into a mold
Can be formed by working on a cast metal
Cannot be heat treated
205. Conventional dental amalgam alloy contains :?
Silver, tin, copper and zinc
Silver, mercury, copper and zinc
Silver, tin, palladium and zinc
Silver, mercury, copper and mercury
206. The type of stress to which dental amalgam is more resistant to :?
Shear stress
Tensile stress
Impact stress
Compressive stress
207. Amalgam is less prone to corrosion :?
If it contains 25-27% of tin
If it contains 4-6% of copper
If devoid of the gamma 2 phase
If it contains zinc
208. Silver in the set amalgam alloy tends to have the following effect :?
Produces contraction
Decreases the setting time
Hydrolyzes the water if contaminated
Decreases ductility
209. The chemistry behind the condensation of the amalgam is to :?
Condense the unattacked gamma II particles
Condense the unattacked gamma particles
Condense the unattacked gamma I particles
To reduce gamma II particules
210. Compared to lathe-cut alloy, spherical dental amalgam alloys :?
Requires less amalgamation time
Requires higher forces of condensation
Requires more mercury for trituration
Have longer setting time
211. The product that is formed on the surface of the amalgam restoration and frequently result in discoloration is :?
Sulphide
Gamma II Phase
Gamma I Phase
Oxide
212. The main function of zinc in amalgam is :?
To produce delayed expansion
To increase the longevity of amalgam after setting
To increase the shelf-life of an amalgam
To prevent the creep
213. The purpose of burnishing the amalgam after condensation is to :?
Reduce surface microporosities
To reduce gamma II particule
To reduce discoloration
To prevent recurrent carries
214. The most commonly used implant type presently is :?
Intramucosal implant
Subperiosteal
Transosteal implant
Endosseous
215. The most commonly employed alloy combination for use in implants is :?
Titanium-aluminum-vanadium alloym-aluminum alloy
Titanium-aluminum-vanadium alloy
Platinum-aluminum-vanadium alloy
Titanium-molybdenum-vanadium alloy
216. Cobalt-chromium alloy is mostly used for the construction of :?
Intramucosal frames
Transosteal frames
Endosseus implants
Subperiosteal
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