Biomaterial Test 0% 5 votes, 5 avg 0 You will have 60 minutes to complete all the questions. After the timer reaches 60 minutes, the exam will end and be saved automatically. Good luck! *Fingers crossed* The timer has been reached. The exam has now been terminated and saved. Biomaterial Test 1 / 60 Minimal thickness of base for adequate thermal insulation is 😕 a. 2 mm b. 1 mm c. 0.5 mm d. 0.75 mm 2 / 60 Elgiloy arch wire is 😕 a. Cobalt-chromium-nickel alloy b. Optical fiber arch wire c. β-titanium arch wire d. Gold alloy 3 / 60 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. 30 mg Hg/m3 of air c. 0.05 mg Hg/m3 of air d. 100 mg Hg/m3 of air 4 / 60 Which of the following polymer systems are used for the organic matrix in composites ? a. Pheyl methacrylate b. Poly (methyl methacrylate) c. Polystyrene d. Bisphenol A-glycidyl methacrylate (Bis-GMA) 5 / 60 The light-cured restorative resins have advantages over chemically activated restorative resins as 😕 a. It has not more working time available b. It has more working time available c. It takes more time for curing d. It is more sensitive to oxygen inhibitors 6 / 60 A potentially toxic element in base metal alloys is 😕 a. Boron b. Beryllium c. Molybdenum d. Magnesium 7 / 60 Which of the following phases in dental amalgam restoration is most prone to electrochemical properties ? a. Cu-Sn b. Sn-Hg c. Ag-Sn d. Ag-Hg 8 / 60 Which of the following statements is true regarding zinc phosphate cement ? a. The least irritant to the pulp b. Has an obtudant effect on the pulp c. Is the oldest luting agent d. Is used as a permanent restorative material in adults 9 / 60 Regarding Knoop hardness number, which of the following material is closest to that of dentine (KHN 65) ? a. Amalgam b. Silicates c. Composites d. Pure gold 10 / 60 The type of stress to which dental amalgam is more resistant to 😕 a. Impact stress b. Tensile stress c. Compressive stress d. Shear stress 11 / 60 Amalgam is less prone to corrosion 😕 a. If it contains 4-6% of copper b. If devoid of the gamma 2 phase c. If it contains 25-27% of tin d. If it contains zinc 12 / 60 Most commonly used pit and fissure sealant is 😕 a. Filled acrylic b. Unfilled acrylic c. Polyurethane d. Bis-GMA resin 13 / 60 Which of the following materials are used for dental implants ? a. Gold alloys b. Titanium c. Cobalt and chromium alloys d. Metal alloys 14 / 60 If the light cure resin is curd in increments, it helps in 😕 a. Providing strength to the restoration b. Compensating polymerization shrinkage c. Achieving complete polymerization d. Saving the application of bonding agent 15 / 60 A small portion of an anterior tooth would most likely be restored with which of the following ? a. Porcelain b. Composite resin c. Gold alloy d. Amalgam 16 / 60 Of the four types of gold casting alloys, the most commonly used for crowns and bridges is 😕 a. Type III b. Type I c. Type IV d. Type II 17 / 60 Which of the composites with the following fillers may be radiopaque ? a. Quartz b. Colloidal silica c. Barium glass d. Lithium aluminum silicate 18 / 60 The most accurate polysulfide impressions are made by using a custom acrylic tray because 😕 a. The tray does not distort during impression making b. It can hold more amount of impression material c. Custom tray made of plastic material ensures a uniform thickness of impression material d. More pressure can be applied during impression making 19 / 60 The constituent that acts as a binder in the investment is 😕 a. Quartz b. Silica c. Gypsum d. Water 20 / 60 Which one of the following is not a criterion for a failed high-copper dental amalgam restorations ? a. Marginal ditching along occlusal margins b. Micrographs of alloys particles. c. Wear facets along the occlusal contach areas d. Creep of the restoration out of the cavity preparation in proximal areas 21 / 60 Thickness of the gel between the tray and tissue for either agar or alginate should always be at least 😕 a. 3 mm b. 2 mm c. 1 mm d. 4 mm 22 / 60 In an alloy oxygen scavenger is 😕 a. Copper b. Silver c. Zinc d. Palladium 23 / 60 Binder in the phosphate investment is 😕 a. Magnesium oxide and monoammonium phosphate b. Phosphoric acid c. Manganese dioxide d. Cristobalite 24 / 60 One of the disadvantages of using quartz as filler in restorative resin is 😕 a. It cannot be reduced to the size of microparticle composite b. It cause abrasion and wearing of opposing tooth surface c. It cannot be polished d. It has low affinity for resin matrix 25 / 60 Dental personnel can do which one of the following to limit their exposure to mercury ? a. Avoid touching freshly mixed amalgam b. Avoid polishing amalgams c. Sterilize amalgam scrap d. Vacuum up a spill immediately 26 / 60 Dental porcelains are manufactured by a process termed as 😕 a. Vulcanizing b. Sintering c. Fritting d. Fusing 27 / 60 Zinc oxide eugenal impression should be removed from oral cavity : a. When it can be easily indented by a blunt instrument b. When the material cannot be intended by a blunt instrument c. Exactly after four minutes after kneading d. When the material is glossy 28 / 60 The chemistry behind the condensation of the amalgam is to 😕 a. Condense the unattacked gamma particles b. Condense the unattacked gamma I particles c. Condense the unattacked gamma II particles d. To reduce gamma II particules 29 / 60 Porcelain-bonded to metal is stronger when fired 😕 a. Under compression b. Several times in air c. Under low temperature d. After metal is tempered 30 / 60 The desirable quality of porcelain is 😕 a. Toughness without brittleness b. Requirement of color c. Translucency d. Thermal expansion 31 / 60 Full denture bases are usually made from which of the following materials ? a. Ceramic b. Acrylic resin c. Composite restorative resins d. Gold alloys 32 / 60 Spot out incorrect statement regarding zinc in dentistry 😕 a. It is low in strength b. Pure zinc has no application in dentistry c. It is relatively soft and ductile d. It does not oxidize 33 / 60 Which of the following is called periphery wax ? a. Utility wax b. Beading wax c. Sticky wax d. Bite registration wax 34 / 60 Excess composite from the labial surfaces can be removed by using 😕 a. Carbide burs at high speed b. Diamond burs at low to medium speed c. Carbide burs at low to medium speed d. Diamond burs at high speed 35 / 60 Crystal structures of metals are all the following except 😕 a. Cubic b. Circular c. Tetragonal d. Monoclinic 36 / 60 When a mechanical device is used for mixing addition silicones 😕 a. Mixing time is reduced b. There is no greater uniformity in proportioning and mixing c. More possibilities of contamination d. Mixing time is long 37 / 60 Which of the following is the best choice of restorative material to achieve moderate to high strength, fluorite release, and esthetics ? a. Composite b. Glass ionomer c. Hybrid ionomer d. Compomer 38 / 60 The reason zinc oxide eugenol cement is used as a temporary restoration 😕 a. It has poor tensile strength b. It does not have anticariogenic activity c. It has an obtudant effect d. It does not form reparative dentin 39 / 60 An anterior fixed partial denture could have facings constructed of which of the following materials ? a. Gold alloy b. Amalgam c. Metal d. Composite resin 40 / 60 The main ingredient of casting waxes is 😕 a. Carnauba wax b. Paraffin wax c. Gum dammar d. Candellila wax 41 / 60 Compared to lathe-cut alloy, spherical dental amalgam alloys 😕 a. Requires more mercury for trituration b. Requires less amalgamation time c. Have longer setting time d. Requires higher forces of condensation 42 / 60 The strain at which the plastic strain develops may be represented by 😕 a. Elastic limit, yield strength, proportional limit b. Elastic limit, modulus of elasticity, tensile strength c. Yield strength, tensile strength, toughness d. Toughness, rigidity, resilience 43 / 60 Color stability of cold-cured resins is inferior to that of heat cured resins due to 😕 a. Variation in the molecular weight of the resin (low mol wt) b. Subsequent oxidation of the tertiary amine c. Decreased polymerization of the resin d. Increased solubility of the resin 44 / 60 Oil of clove is sometimes used in preference to eugenal in ZOE paste because : a. To increase setting time b. It increases mixing property of paste and therefore improves impression recorded c. Reduces burning sensation of paste d. Has a better reaction with zinc oxide 45 / 60 Which of the following is a measure of resistance to fracture ?: a. Springiness b. Hardness c. Toughness d. Brittleness 46 / 60 Cobalt-chromium alloy is mostly used for the construction of 😕 a. Intramucosal frames b. Subperiosteal c. Transosteal frames d. Endosseus implants 47 / 60 The following statements about dental porcelains are true except 😕 a. Crystalline nature b. Undergoes discoloration c. It is brittle in nature d. Undergoes firing shrinkage 48 / 60 Condensation of porcelain is done by all the methods except 😕 a. Spatulation method b. Brush addition technique c. Vibration method d. Ceramming method 49 / 60 Setting of plaster of Paris is a result of 😕 a. Loss of water from hemihydrates b. Solubility difference between hemihydrates and dehydrate c. Indirect interaction between hemihydrates d. Interaction between hemihydrates and water 50 / 60 Which of the following properties would be of least importance, when selecting an impression material ? a. Dimensional stability b. Adhesion c. Flow d. Biocompatibility 51 / 60 Following are the functions of impression compound except 😕 a. To make special tray for final impression b. To make individual die impression with copper band c. To record mucostatic impressions d. To make impression of edentulous ridge 52 / 60 Stearic acid in impression compound 😕 a. Increase setting time b. Reduces brittleness c. Reduces plasticity d. Reduces flow 53 / 60 Adhesion in composites is due to 😕 a. Presence of smear layer b. True chemical bonding to tooth structure c. Mechanical interlocking d. Cohesion 54 / 60 One of the following statements which one is incorrect regarding addition silicones 😕 a. Undetectable distortion on removal b. Can be used in automixing devices c. No evolution of any byproduct under all circumstances d. Dimensionally stable even after 1 week 55 / 60 Which of the following represents the maximum safe concentration of mercury vapor in the breathing zone for a 40-hour workweek ? a. 30 ng Hg/m3 of air b. 0.05 mg Hg/m3 of air c. All are corrects d. 100 ng Hg/m3 of air 56 / 60 Chemically cured resin shrinks:? a. Away from the light source b. Towards the center of bulk of material c. On the base only d. On the surface only 57 / 60 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. Proportioning mercury and alloy into a friction-fit capsule d. Mixing in a mortar and pestle 58 / 60 The impression material which is routinely used in auto mixing devicee system is 😕 a. Polyvinyl siloxane b. Condensation silicone c. Polyether d. Polysulfied 59 / 60 The primary difference between low- and high-copper amalgams is which of the following ? a. The amount of copper and zinc b. The amount of copper and silver c. The amount of copper and tin d. The amount of copper 60 / 60 The temperature at which a solid changes into liquid is called 😕 a. Specific temperature b. Temperature of vaporization c. Fusion temperature d. 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