/218 385 Biomaterial Preparation (Dr. Yin Sithoen) 1 / 218 1) Dental porcelains are manufactured by a process termed as 😕 a. Fritting b. Sintering c. Vulcanizing d. Fusing 2 / 218 2) One of the disadvantages of using quartz as filler in restorative resin is 😕 a. It cannot be polished b. It has low affinity for resin matrix c. It cannot be reduced to the size of microparticle composite d. It cause abrasion and wearing of opposing tooth surface 3 / 218 3) Impression plaster is a 😕 a. Mucocompressive material b. Mucostatic material c. Reversible impression material d. Thermoplastic material 4 / 218 4) Which of the following statements is true regarding zinc phosphate cement ? a. Is the oldest luting agent b. Is used as a permanent restorative material in adults c. The least irritant to the pulp d. Has an obtudant effect on the pulp 5 / 218 5) Which of the following is the best choice of restorative material to achieve moderate to high strength, fluorite release, and esthetics ? a. Composite b. Compomer c. Glass ionomer d. Hybrid ionomer 6 / 218 6) Chemically cured resin shrinks:? a. Towards the center of bulk of material b. Away from the light source c. On the base only d. On the surface only 7 / 218 7) Minimum light exposure time for composite resins should be 😕 a. 5 sec b. 20 sec c. 40 sec d. 10 sec 8 / 218 8) Which of the following composite is recommended for non stress bearing anterior restoration ? a. Conventional composites b. Hybrid composites c. Small particles d. Microfilled composites 9 / 218 9) The catalyst used for condensation silicones is 😕 a. Platinum b. Stannous octoate c. Oleic acid d. Lead dioxide 10 / 218 10) The energy absorbed by a material when it is stressed to its proportional limit is 😕 a. Impact strength b. Flexibility c. Resilience d. Toughness 11 / 218 11) The light-cured restorative resins have advantages over chemically activated restorative resins as 😕 a. It has not more working time available b. It is more sensitive to oxygen inhibitors c. It takes more time for curing d. It has more working time available 12 / 218 12) Commonly used coloring agent in impression plaster is 😕 a. Metallic oxide b. Alizarin red c. Congo red d. Indigo dye 13 / 218 13) The greatest amount of dimensional change after setting is exhibited by 😕 a. Polyethers b. Polysulfides c. Addition silicones d. Condensation silicones 14 / 218 14) Softening of impressing compound is best accomplished by 😕 a. Dry heat b. Open flame c. Oil bath d. Water bath 15 / 218 15) Which of the following is called periphery wax ? a. Utility wax b. Beading wax c. Sticky wax d. Bite registration wax 16 / 218 16) Nickel sensitivity in the general population is 😕 a. 3% for women b. 3% for men c. 11% for women d. 1% in the overall population 17 / 218 17) Which of the following is recommended as an adhesive to trays with polysulfides ? a. Ethyl silicate b. Styrene-acrylonitrile c. Polydimethyl siloxane d. Acrylic resin 18 / 218 18) The temperature at which a solid changes into liquid is called 😕 a. Fusion temperature b. Specific temperature c. Temperature of vaporization d. Latent heat 19 / 218 19) For proper wetting, contact angle should be ideally 😕 a. 00 b. 450 c. 900 d. 600 20 / 218 20) Cavity varnish should not be applied when the following is used as a filling material 😕 a. Zinc phosphate b. Silicate c. Direct resin-filling material d. Amalgam 21 / 218 21) Resistance of a liquid to motion is called 😕 a. Viscosity b. Creep c. Springiness d. Diffusion 22 / 218 22) The gelation temperature of agar hydrocolloid impression material should be 😕 a. 45-600C b. 100C higher than mouth temperature c. 37-450C d. Far below the oral temperature 23 / 218 23) The main ingredient of casting waxes is 😕 a. Gum dammar b. Paraffin wax c. Candellila wax d. Carnauba wax 24 / 218 24) Acrylic resins are used in which of the following ? a. Denture bases b. Anterior onlays c. Posterior inlays d. Ceramic ( porcelain )-fused-to-metal crowns 25 / 218 25) Property which distinguishes composites from filled acrylic resins 😕 a. Bonding with tooth structure b. Bonding between coupling agent and tooth structure c. Adhesive bonding between matrix and filler d. Bonding between coupling agent and filler 26 / 218 26) Conventional dental amalgam alloy contains 😕 a. Silver, tin, palladium and zinc b. Silver, tin, copper and zinc c. Silver, mercury, copper and mercury d. Silver, mercury, copper and zinc 27 / 218 27) An anterior fixed partial denture could have facings constructed of which of the following materials ? a. Composite resin b. Metal c. Amalgam d. Gold alloy 28 / 218 28) One of the following statements which one is incorrect regarding addition silicones 😕 a. Dimensionally stable even after 1 week b. Undetectable distortion on removal c. No evolution of any byproduct under all circumstances d. Can be used in automixing devices 29 / 218 29) Gold with high percentage elongation is best for 😕 a. To remove metallic oxide b. To revert sagging during firing c. Increase the bond strength d. To improve the castability 30 / 218 30) Cobalt-chromium alloy is mostly used for the construction of 😕 a. Endosseus implants b. Subperiosteal c. Intramucosal frames d. Transosteal frames 31 / 218 31) Oxalates, carbonates, potassium, trisodium phosphates are added to alginate as 😕 a. Retarders b. Accelerators c. Reactors d. Fillers 32 / 218 32) Which one of the following phases in dental amalgam restoration has the best mechanical properties ? a. Sn-Hg b. Cu-Sn c. Ag-Su d. Ag-Hg 33 / 218 33) Which of the following composites give rough surfaced finish ? a. Small particle filled composites b. Conventional composites c. Hybrid composites d. Microfilled composites 34 / 218 34) When the gold content of gold alloys increases 😕 a. The percentage elongation decrease b. The corrosion resistance increases c. Ductility decrease d. The hardness decrease 35 / 218 35) Which statements are true for bonding of amalgam to tooth structure ? a. The most effective bonding agents contain copalite. b. Shear bond strength using amalgam bonding to teeth in clinically proven to be as high as that for bonding composites to teeth. c. The use of amalgam bonding reduces marginal leakage of amalgam restorations. d. The use of amalgam bonding restores the strength of the clinical crown to its original condition. 36 / 218 36) Bis-GMA is a reaction product of 😕 a. Bis-phenol-A and glycidyl methacrylate b. Urethane dimethacrylate and glycidyl c. Bis-phenol-A and methyl methacrylate d. Bis-phenol-A and urethane dimethacrylate 37 / 218 37) The desirable quality of porcelain is 😕 a. Requirement of color b. Thermal expansion c. Translucency d. Toughness without brittleness 38 / 218 38) Which one of the following mixing methods permits the escape of dental amalgam mercury vapor ? a. Triturating precapsulated alloy and mercury b. A cover over the mixing arms on a triturator c. Proportioning mercury and alloy into a friction-fit capsule d. Mixing in a mortar and pestle 39 / 218 39) Which of the following initiator-accelerator systems is needed for a light-activated composite? a. Organic acid-peroxide b. Diketone-amine c. Organic acid-metal ion d. Peroxide-amine 40 / 218 40) Silver in the set amalgam alloy tends to have the following effect 😕 a. Hydrolyzes the water if contaminated b. Produces contraction c. Decreases the setting time d. Decreases ductility 41 / 218 41) A glaze is placed over the finished composite restoration to 😕 a. Create a rough surface that is less receptive to extrinsic stain and plaque retention b. No provide a better peripheral seal c. To change the shade d. To reduce surface porosities 42 / 218 42) Which of the following metals currently are used in dental alloys ? a. Waxe b. Ceramic c. Gold d. Glass ionomer 43 / 218 43) Minimal thickness of base for adequate thermal insulation is 😕 a. 0.75 mm b. 0.5 mm c. 1 mm d. 2 mm 44 / 218 44) For luting purpose, the film thickness should be 😕 a. 25 μm or less b. up to 75 μm c. ideally 100 μm d. minimum 50 μm 45 / 218 45) Which of the following is a measure of resistance to fracture ?: a. Brittleness b. Toughness c. Springiness d. Hardness 46 / 218 46) Spot out incorrect statement regarding zinc in dentistry 😕 a. It is relatively soft and ductile b. Pure zinc has no application in dentistry c. It is low in strength d. It does not oxidize 47 / 218 47) Ideal method firing of porcelain is by using 😕 a. Longer firing at high temperatures b. Shorter firing at higher temperatures c. Longer firing at low temperatures d. Shorter firing at low temperatures 48 / 218 48) For each property, list the amalgam type (irregular low-copper, admixed high-copper, and spherical high-copper ) that has the highest value?. a. Tensile strength spherical high-copper b. Creep irregular high-copper c. Creep irregular low-copper d. 1-hour compressive strength spherical high-copper 49 / 218 49) Commonly used viscosity controller in composites is 😕 a. TEG-DMA b. Methyl methacrylate c. Polyurethanes d. Bis-GAM 50 / 218 50) Modifiers are added to plaster of Paris mainly to 😕 a. Reduce porosity b. Increase strength c. Regulate the setting time d. Get a smooth surface 51 / 218 51) The appropriate proportion of polymer to monomer component of dental resin by volume is generally 😕 a. 1:2 b. 1:3 c. 2:1 d. 3:1 52 / 218 52) In a porcelain fused to metal restoration, the porcelain is-bonded to metal by 😕 a. Chemical bonding b. Chemico-mechenical bonding c. High malleafility of metal d. Hight ductility of metal 53 / 218 53) The main use of zinc oxide eugenol cement is 😕 a. Permanent restoration b. Indirect pulp capping agent c. Base d. Temporary restoration 54 / 218 54) Polyether is different from other elastomers in the following aspects 😕 a. Hydropholic in nature b. High stiffiness c. Can not be used as light cure material d. Low stiffness 55 / 218 55) Which of the following properties would be of least importance, when selecting an impression material ? a. Biocompatibility b. Dimensional stability c. Flow d. Adhesion 56 / 218 56) A small portion of an anterior tooth would most likely be restored with which of the following ? a. Amalgam b. Composite resin c. Porcelain d. Gold alloy 57 / 218 57) Strength of dental porcelain is dependent on 😕 a. Rough b. No internal structure c. Composition d. Resistance to fusion 58 / 218 58) Which of the following waxes is obtained from distillation of petroleum ? a. Montan and Japan coco b. Paraffin and microcrystalline wax c. Carnauba and candellia d. Spermitic and bees wax 59 / 218 59) Most common use of Zinc oxide eugenol paste 😕 a. Surgical paste b. Wash impression for edentulous patients c. As interocclusal record material d. Dual impression for Partially edentulous patients 60 / 218 60) The purpose of burnishing the amalgam after condensation is to 😕 a. To reduce discoloration b. To prevent recurrent carries c. To reduce gamma II particule d. Reduce surface microporosities 61 / 218 61) Setting time of alginate can be better controlled by 😕 a. Mixing time b. Temperature of water used of mixing c. Changing water: powder ratio d. Chemical accelerators and retarders 62 / 218 62) A full crown on a maxillary anterior tooth may be restored with which of the following restorative materials ? a. Amalgam b. Composite resin c. Gold alloys d. Ceramic 63 / 218 63) Stearic acid in impression compound 😕 a. Reduces brittleness b. Reduces plasticity c. Reduces flow d. Increase setting time 64 / 218 64) In UV curing system the activator employed is 😕 a. Methyl methacrylate b. Hydroquinone c. Benzoin methyl ether d. Dibutyl phthalate 65 / 218 65) Following are the functions of impression compound except 😕 a. To make special tray for final impression b. To make impression of edentulous ridge c. To make individual die impression with copper band d. To record mucostatic impressions 66 / 218 66) Hypersensitivity reactions like contact dermatitis is caused by 😕 a. Condensation silicones b. Addition silicones c. Polyether d. Polysulfides 67 / 218 67) The type of stress to which dental amalgam is more resistant to 😕 a. Impact stress b. Shear stress c. Compressive stress d. Tensile stress 68 / 218 68) Amalgam is less prone to corrosion 😕 a. If it contains 25-27% of tin b. If devoid of the gamma 2 phase c. If it contains 4-6% of copper d. If it contains zinc 69 / 218 69) Biting force in the molar region ranges from 😕 a. 900-1000 N b. 600-1000 N c. 1000-1300 N d. 400-890 N 70 / 218 70) Greater ratio fo zinc oxide to eugenol will have the following effect on setting time 😕 a. Increases setting time b. Decreases setting time c. Does not alter setting time d. Depends on rate of mixing 71 / 218 71) Alginate impression material deteriorates rapidly at 😕 a. Elevated temperature b. Normal room temperature c. Temperature does not cause any change in shelf-life d. Low temperature 72 / 218 72) Thickness of the gel between the tray and tissue for either agar or alginate should always be at least 😕 a. 4 mm b. 3 mm c. 1 mm d. 2 mm 73 / 218 73) The most effective cement in stimulating tertiary dentin is 😕 a. Zinc phosphate b. Zinc silicophoshpate c. Polycardoxylate d. Calcum hydroxide 74 / 218 74) Which of the following uses a hardened steel ball indenting tool ? a. Vichers hardness test b. Rockwell hardness test c. Knoop hardness test d. Brinell hardness test 75 / 218 75) The most commonly used implant type presently is 😕 a. Endosseous b. Subperiosteal c. Transosteal implant d. Intramucosal implant 76 / 218 76) Sulfur contamination from natural latex gloves inhibits the setting of 😕 a. Polyvinyl siloxane b. Polyether c. Alginate d. Zinc oxide eugenol impression paste 77 / 218 77) Which of the following components acts as a refractory material in porcelain ? a. Potash b. Kaolin c. Silica d. Feldspar 78 / 218 78) Which of the following statements about laboratory composites are true ? a. Fiber reinforcement increases their strength but decrease their rigidity. b. Bridge prepared from laboratory composites require a metal substructure. c. Restorations prepared from laboratory composites typically are cemented with zinc phosphate cement. d. Curing using light, heat, and pressure increase the wear resistance. 79 / 218 79) Main disadvantage of denture base soft reliner is 😕 a. It has not to be changed over a period of time b. It can not lead to cleaned property c. It can not lead to fungal growth d. It can be cleaned properly 80 / 218 80) Inorganic phase in a composite matrix 😕 a. Increases the polymerization shrinkage b. Increases coefficient of thermal expansion c. Decreases the mechanical strength d. Increases the mechanical strength 81 / 218 81) All of the following are properties of Co-Cr-Ni wires except 😕 a. They cannot be soldered or welded b. They can be heat treated c. They have excellent tarnish and corrosion resistance d. Their hardness is comparable to stainless steel 82 / 218 82) KHN of enamel is 😕 a. 300 b. 600 c. 100 d. 90-100 83 / 218 83) Passiveness of chrome cobalt alloys is due to formation of 😕 a. Cobalt oxide b. Chromium oxide c. Chromium carbide d. Ferric oxide 84 / 218 84) A potentially toxic element in base metal alloys is 😕 a. Magnesium b. Molybdenum c. Beryllium d. Boron 85 / 218 85) The constituent that acts as a binder in the investment is 😕 a. Silica b. Quartz c. Water d. Gypsum 86 / 218 86) Which of the following mixing methods permits the escape of dental amalgam mercury vapor ? a. A cover over the mixing arms on a triturator b. Triturating precapsulated alloy and mercury c. Mixing in a mortar and pestle d. Proportioning mercury and alloy into a friction-fit capsule 87 / 218 87) Side effects and complications resulting from treatment by a physician or dentist is 😕 a. Teratogenesis b. Iatrogenesis c. Biocompatibility d. Carcinogenesis 88 / 218 88) Distortion on removal from undercuts in addition silicones is very less due to 😕 a. Increased strain rate on unset material b. Shrinkage of material c. Lowest strain in compression d. Stiffness of the material 89 / 218 89) Binder in the phosphate investment is 😕 a. Cristobalite b. Magnesium oxide and monoammonium phosphate c. Phosphoric acid d. Manganese dioxide 90 / 218 90) Noble metal alloys are classified according to their 😕 a. Melting temperature b. Malleability c. Castability d. Dental function 91 / 218 91) Which of the following sentences describes the construction of removable partial dentures ? a. Artificial acrylic teeth are attached b. They are attached to upper natural teeth with cements, c. They are attached to lower natural teeth with cements, d. They are attached to natural teeth with cements, 92 / 218 92) Zinc oxide eugenal impression should be removed from oral cavity : a. When the material cannot be intended by a blunt instrument b. When the material is glossy c. When it can be easily indented by a blunt instrument d. Exactly after four minutes after kneading 93 / 218 93) Which has the highest viscoelastic property and requires more time to recover from deformation ? a. Polysulfide b. Condensation silicone c. Addition silicone d. Polyether 94 / 218 94) Compared to lathe-cut alloy, spherical dental amalgam alloys 😕 a. Requires less amalgamation time b. Requires higher forces of condensation c. Requires more mercury for trituration d. Have longer setting time 95 / 218 95) Which of the following elastomers is suited for multiple cast pouring 😕 a. Polyether b. Condensation silicone c. Polysulfide d. Addition silicone 96 / 218 96) Impression compound is characterized by 😕 a. Crystalline in nature with definite melting point b. Amorphous in nature with high thermal conductivity c. Crystalline in nature with high thermal conductivity d. Amorphous in nature with low thermal conductivity 97 / 218 97) The impression material which is routinely used in auto mixing devicee system is 😕 a. Polysulfied b. Polyvinyl siloxane c. Polyether d. Condensation silicone 98 / 218 98) Most commonly used pit and fissure sealant is 😕 a. Polyurethane b. Filled acrylic c. Unfilled acrylic d. Bis-GMA resin 99 / 218 99) Which of the following material has a high coefficient of thermal expansion ? a. Unfilled acrylic resin b. Composite resin c. Silicate cement d. Glass ionomer cement 100 / 218 100) Commonly used filler in composite is 😕 a. Colloidal silica b. Aluminum c. Glass d. Quartz 101 / 218 101) Which of the following statements apply to the packable composites ? a. Radiopaque b. Their depth of cure allows bulk polymerization, which has been shown to be clinically effective. c. Their wear rate is low (3.5 μm/year). Which is similar to that of amalgam. d. They are radiolucent. 102 / 218 102) If the light cure resin is curd in increments, it helps in 😕 a. Compensating polymerization shrinkage b. Achieving complete polymerization c. Saving the application of bonding agent d. Providing strength to the restoration 103 / 218 103) Higher mercury left in an amalgam leads to which of the following ? a. Higher creep b. Low corrosion c. Higher strength d. High corrosion 104 / 218 104) The main advantage of composites compared to silicates cement is 😕 a. Practically insoluble in oral fluids b. Coefficient of thermal expansion close to tooth structure c. High modulus of resilience d. Color matching with the tooth structure is excellent 105 / 218 105) Materials having coefficient of thermal expansion close to the tooth structure 😕 a. Amalgam b. Unfilled c. Silicate cement d. Glass ionomer cement 106 / 218 106) Color stability of cold-cured resins is inferior to that of heat cured resins due to 😕 a. Decreased polymerization of the resin b. Variation in the molecular weight of the resin (low mol wt) c. Increased solubility of the resin d. Subsequent oxidation of the tertiary amine 107 / 218 107) An anterior fixed partial denture could have facings constructed of which of the following materials ? a. Silver alloys b. Amalgam c. Gold alloy d. Ceramic 108 / 218 108) Working time of denture resin should be at least 😕 a. 20 minutes b. 15 minutes c. 10 minutes d. 5 minutes 109 / 218 109) The most commonly employed alloy combination for use in implants is 😕 a. Titanium-platinum-aluminum alloy b. Titanium-molybdenum-vanadium alloy c. Platinum-aluminum-vanadium alloy d. Titanium-aluminum-vanadium alloy 110 / 218 110) Oil of clove is sometimes used in preference to eugenal in ZOE paste because : a. It increases mixing property of paste and therefore improves impression recorded b. Has a better reaction with zinc oxide c. Reduces burning sensation of paste d. To increase setting time 111 / 218 111) Which of the following base is contraindicated for composites ? a. Zinc phosphate b. Glass ionomer cement c. Calcium hydroxide d. Zinc oxide eugenol 112 / 218 112) Dental personnel can do which one of the following to limit their exposure to mercury ? a. Sterilize amalgam scrap b. Avoid touching freshly mixed amalgam c. Vacuum up a spill immediately d. Avoid polishing amalgams 113 / 218 113) Which one of the following represents the maximum safe concentration of mercury vapor in the breathing zone for a 40-hour work week ? a. 0.04 mg Hg/m3 of air b. 0.05 mg Hg/m3 of air c. 100 mg Hg/m3 of air d. 30 mg Hg/m3 of air 114 / 218 114) Calcium hydroxide is used for 😕 a. Pulp capping b. To prevent recurrent caries c. Reinforce the restoration d. Reduce maginal leakage 115 / 218 115) The fluoride release from glass ionomer cement is 😕 a. 0.75 mg during the first week b. 0.005 mg during the first week c. 0.0005 mg during the first month d. 0.075 mg during the first month 116 / 218 116) The primary difference between low- and high-copper amalgams is which of the following ? a. The amount of copper and silver b. The amount of copper and tin c. The amount of copper d. The amount of copper and zinc 117 / 218 117) Which of the following statements is incorrect regarding hydroxyapatite as an implant material ? a. It is produced in block or granula form b. It is a bio-inert material c. It is used for augmenting alveolar ridges of filling bony defects d. This material in granular form and is difficult 118 / 218 118) Wrought metal 😕 a. Cannot be rendered corrosion resistant b. Can be formed by pouring molten metal into a mold c. Cannot be heat treated d. Can be formed by working on a cast metal 119 / 218 119) The cavity for a GIC restoration is preconditioned with 😕 a. Phosphoric acid for 60 seconds b. Polyacrylic acid for 10 seconds c. Phosphoric acid for 10 seconds d. Polyacrylic acid for 60 seconds 120 / 218 120) Which of the following materials are used for dental implants ? a. Titanium b. Metal alloys c. Cobalt and chromium alloys d. Gold alloys 121 / 218 121) Gypsum investments should not be heated above 😕 a. 17000C b. 7000C c. 10000C d. 4500C 122 / 218 122) The reason for hydroxyapatite coating on implant biomaterials is 😕 a. Prolonged healing time b. Presence of fibrous tissue c. Greater bony opposition d. Lesser bony apposition 123 / 218 123) In a porcelain fused to metal restoration, when the coefficient of thermal expansion of metal and porcelain are different 😕 a. Porcelain will wear off b. Porcelain will not bond with metal c. Porcelain will provide good shade d. Porcelain will crack on cooling 124 / 218 124) Which of the following is used to alter contour of impression trays ? a. Carding wax b. Beading wax c. Boxing wax d. Utility wax 125 / 218 125) Metal has the following properties except 😕 a. Metal is any element that ionizes positively in solution b. Electroplated silver and copper are used in dies c. Pure metals are not useful in dentistry d. All metals do not have same degrees of strength and plasticity 126 / 218 126) 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 ? a. Esthetics b. High strength c. Thermal insulation d. Ease of casting 127 / 218 127) The main resin constituent of polishable composite resin is 😕 a. Polymethyl methacrylate b. Polycaronate c. Urethane dimethacrylate d. Cyanoacrylate 128 / 218 128) Hand instruments for composites are made of 😕 a. Stainless steel b. Teflon-coated metal c. Titanium d. Carbon steel 129 / 218 129) Greening effect of porcelain is due to 😕 a. Palladium b. Golde c. Platinum d. Silver 130 / 218 130) Strain that occurs when the material is stressed to its proportional limit is called 😕 a. Flexibility b. Modulus of elasticity c. Resilience d. Toughness 131 / 218 131) Which of the following sentences describes the construction of removable partial dentures ? a. Artificial waxes teeth are attached b. They are attached to natural teeth with cements, c. They are removable and attached to teeth with clasps. d. Carbone steal 132 / 218 132) The cracks formed on the ceramic during cooling because 😕 a. The cooling of the outer and the inner layer occurs at the same rate b. Due to external forces c. The inner layer cools more rapidly than the outer layer d. The outer layer cools more rapidly than the interior 133 / 218 133) Ideal metal used for electroplating polysulfide impression is 😕 a. Cobalt b. Silver c. Nickel d. Copper 134 / 218 134) One of the following statements which one is incorrect regarding polyether : a. Aromatic sulfonate ester acts as a cross linking agent b. The base paste consists of polyether polymer c. The main chain of polyether consists of copolymer of ethylene oxide and tetrahydrofuran d. The main chain consists of copolymer of methylene oxide and tetrahydrofuran 135 / 218 135) Which of these statements apply to the filler particles of composites ? a. Microhybrid composites contain as much as 84% filler by weight. b. Microfilled composites contain more filler than all-purpose composites. c. Microfilled d. All are correct 136 / 218 136) Carnauba wax is preferred to candelilla wax as 😕 a. It is sticky b. It has low melting temperature c. It provides luster to the pattern d. It is harder and has less flow 137 / 218 137) The light from the visible light curing unit can cause 😕 a. Cataract b. Iritis c. Corneal ulceration d. Retinal damage 138 / 218 138) Silver has all the following characteristics except 😕 a. Whitens when added to alloys b. Silver in pure form is not used in dental restorations c. Silver points serve as a root canal filling material d. Addition of palladium to silver increases corrosion 139 / 218 139) Excess composite from the labial surfaces can be removed by using 😕 a. Carbide burs at low to medium speed b. Carbide burs at high speed c. Diamond burs at low to medium speed d. Diamond burs at high speed 140 / 218 140) Glass ionomer cenment is not recommended for 😕 a. Class IV resoration b. Class I restoration c. Class III restoration d. Class V restoration 141 / 218 141) The tendency of stainless steel to break under repeated condition of cyclic stressing below the ultimate strength is 😕 a. Resilience b. Fatigue c. Ductility d. Creep 142 / 218 142) The product that is formed on the surface of the amalgam restoration and frequently result in discoloration is 😕 a. Gamma II Phase b. Gamma I Phase c. Oxide d. Sulphide 143 / 218 143) Which of the following polymer systems are used for the organic matrix in composites ? a. Polystyrene b. Pheyl methacrylate c. Bisphenol A-glycidyl methacrylate (Bis-GMA) d. Poly (methyl methacrylate) 144 / 218 144) In the cavities which are more than 2mm deep a light-cured restoration is 😕 a. Not indicated b. Restoration should be build in increments c. Fifth generation bonding agent should be applied d. Cured for longer period 145 / 218 145) Dispensing composite resins using a syringe is advantageous because it 😕 a. Decreases air voids in the restoration b. Increases surface smoothness c. Conserves the material d. Increases strength and abrasive resistance 146 / 218 146) Which of the following statements about adhesion of composite restorations to tooth structure are true ? a. The bonding agent forms a hybrid layer with enamel. b. The bonding agent forms a micromechanical bond with enamel but a chemical bond with dentin. c. Most bonding agent bond more effectively to a dry tooth surface. d. Bonding is achieved to enamel by application of an acid etchant followed by application of a bonding agent and then the composites resin. 147 / 218 147) Condensation of porcelain is done by all the methods except 😕 a. Vibration method b. Brush addition technique c. Ceramming method d. Spatulation method 148 / 218 148) The physical property measured in terms of the deformation of the structure per until dimensions is ? a. Strain b. Amorphous material c. Space lattice d. Stress 149 / 218 149) Setting of plaster of Paris is a result of 😕 a. Indirect interaction between hemihydrates b. Interaction between hemihydrates and water c. Solubility difference between hemihydrates and dehydrate d. Loss of water from hemihydrates 150 / 218 150) The main function of zinc in amalgam is 😕 a. To increase the shelf-life of an amalgam b. To increase the longevity of amalgam after setting c. To prevent the creep d. To produce delayed expansion 151 / 218 151) Which one of the following phases in dental amalgam restoration is most prone to electrochemical corrosion ? a. Sn-Hg b. Ag-Su c. Cu-Sn d. Ag-Hg 152 / 218 152) Regarding Knoop hardness number, which of the following material is closest to that of dentine (KHN 65) ? a. Pure gold b. Amalgam c. Composites d. Silicates 153 / 218 153) The reason zinc oxide eugenol cement is used as a temporary restoration 😕 a. It does not form reparative dentin b. It has poor tensile strength c. It does not have anticariogenic activity d. It has an obtudant effect 154 / 218 154) A measure of ductility of a material is referred to as 😕 a. Percentage elongation b. Flexibility c. Yield strength d. Proportional limit 155 / 218 155) Which of the following properties of calcium hydroxide cement help in the formation of reparative dentin ? a. No antibacterial action b. Low alkalinity c. High alkalinity d. No Protein lysing effect 156 / 218 156) The function of gum dammar in inlay wax is 😕 a. To improve smoothness of pattern b. Less strength to wax c. No resistance to carving d. No smoothness of pattern 157 / 218 157) Which one of the following is not true about high-copper dental amalgam restorations ? a. Produce excessive creep b. Contain both Sn and Ag in the composition as well c. Better corrosion resistance than low-copper dental amalgams d. Restorations are more brittle than low-copper versions 158 / 218 158) Main disadvantage of laminate technique of making impression is : ? a. Cost factor is high b. Maximum details are not produced c. Bond between agar and alginate is not very strong d. Difficult to manipulate 159 / 218 159) Porcelain-bonded to metal is stronger when fired 😕 a. Under low temperature b. Under compression c. After metal is tempered d. Several times in air 160 / 218 160) In alginate impression the final gel is 😕 a. Calcium alginate b. Sodium alginate c. Calcium sulphate d. Sodium sulphate 161 / 218 161) The noble or base metal alloys used for PFM should have the following requisite : a. Should bond with dental porcelain b. Should be brittle c. Coefficient of thermal expansion should not be compatible with porcelain d. Its melting temperature should be low in comparison with firing temperature of porcelain 162 / 218 162) The most accurate polysulfide impressions are made by using a custom acrylic tray because 😕 a. The tray does not distort during impression making b. Custom tray made of plastic material ensures a uniform thickness of impression material c. It can hold more amount of impression material d. More pressure can be applied during impression making 163 / 218 163) Which of the following phases in dental amalgam restoration has the best mechanical properties ? a. Ag-Hg b. Sn-Hg c. Cu-Sn d. Ag-Sn 164 / 218 164) In deep caities, the resin which remains unpolymerized can cause 😕 a. Porosity in restoration b. Pulp inflammation c. Sagging of restoration d. Secondary caries 165 / 218 165) Which one of the following is not a criterion for a failed high-copper dental amalgam restorations ? a. Wear facets along the occlusal contach areas b. Micrographs of alloys particles. c. Creep of the restoration out of the cavity preparation in proximal areas d. Marginal ditching along occlusal margins 166 / 218 166) Contamination of zinc-containing amalgam by moisture during triturating or condensation : a. Has no appreciable effect on properties except to the susceptibility to tarnish b. Results in a sharp decrease in flow c. Results in a marked expansion d. Increases the setting time 167 / 218 167) The following statements about dental porcelains are true except 😕 a. Undergoes discoloration b. It is brittle in nature c. Undergoes firing shrinkage d. Crystalline nature 168 / 218 168) Stiffness of the material with passage of time is maximum in 😕 a. Condensation silicones b. Addition silicones c. Polysulfides d. Polyether 169 / 218 169) All are properties of waxes except 😕 a. Plastic deformation b. Creep c. Flow d. Solidification shrinkage 170 / 218 170) In dental plaster the main ingredient is 😕 a. Calcium anhydrate b. Calcium phosphate c. Calcium sulfate dehydrate d. Calcium sulfate hemihydarate 171 / 218 171) Porcelain denture teeth 😕 a. Have higher coefficient of thermal expansion than resin teeth b. Are more resistant of abrasion than gold c. Have decreased abrasion resistance than dentin d. Are easy to grind and polish 172 / 218 172) Which of the following phases in dental amalgam restoration is most prone to electrochemical properties ? a. Ag-Sn b. Sn-Hg c. Cu-Sn d. Ag-Hg 173 / 218 173) Proportional limit is defined as : a. The stress/strain ratio within the elastic limit in a structure b. A deformation resulting from an applied load c. The maximum stress that can be induced without permanent deformation d. The maximum force required to cause a structure to break 174 / 218 174) Crystal structures of metals are all the following except 😕 a. Cubic b. Circular c. Tetragonal d. Monoclinic 175 / 218 175) The physical properties most desirable in set amalgam are which of the following ? a. Low strength, low creep, low corrosion b. Higher strength, high creep, low corrosion c. Higher strength, high creep, high corrosion d. Higher strength, low creep, low corrosion 176 / 218 176) Which of the following is a measure of resistance to fracture ? a. Springiness b. Toughness c. Brittleness d. Hardness 177 / 218 177) Which of the following waxes used to align of castings before soldering ? a. Carding wax b. Utility wax c. Base plate wax d. Sticky wax 178 / 218 178) Clinical significance of smear layer : a. Provides calcium for adhesion of composites b. Increases the bonding action of the bonding agent c. Improve the strength of the composite d. Bonded to tooth structure and prevents composite adhesion 179 / 218 179) When a mechanical device is used for mixing addition silicones 😕 a. Mixing time is reduced b. Mixing time is long c. There is no greater uniformity in proportioning and mixing d. More possibilities of contamination 180 / 218 180) The byproduct in condensation silicones is 😕