2016 Flashcards
Which of the following monomers is used as a cross linking agent in dental polymers? A) MMA B) ethylene methacrylate C) ethylene glycol dimethecrylate D) triethylene glyco dimethacrylate
C) ethylene glycol dimethecrylate
Which increased glass transition temperature of polymer? A) long branches B) bulky side groups C) secondary bounding D) plasticizers
C
Which gypsum product do you use to pour a diagnostic of your patient? A) type I B) type II C) type III D) type IV E) type V
C) type III
Step growth polymerization:
A) requires at least 2 dif chemical species of reactants
B) often results in low molecular weight products
C) requires reactants that are least difunctional
D) has very limited use in dental restorative materials
E) all of the above
E) all of the above
Which of the following monomers is considered core of dental polymers? A) urethane dimethacrylate B) methyl methacrylate C) ethyl methacrylate D) vinyl acrylic
B) MMA
What gypsum product would you use for mounting casting? A) high for strength stone B) dental stone C) model plaster D) impression plaster
D) impression plaster
What is the reactor in alginate impression materials? A) potassium alginate B) sodium alginate C) calcium sulfate dihydate D) sodium alginate
C) calcium sulfate dihydate
What is the key factor to consider regarding sol-gel transformation in agar impression materials? A) water content B) temperature C) equipment D) none of the above
Water content
When mixing an alginate impression, gelation develops as a result of formation of which of the following products: A) calcium alginate B) potassium alginate C) ammonium alginate D) sodium alginate
A) calcium alginate
What is a soluble form of alginate salts? A) Potassium alginate B) Sodiumphosphate C) Calcium sulfate dihydrate D) All are soluble alginate salts
A) Potassium alginate
Which of these materials is known to inhibit resin polymerization? A) Benzoylperoxide B) Camphoroquinone C) Eugenol D) Aromatic amine
C) Eugenol
When calcium sulfate dihydrate mineral is heated under stream pressure, it will produce: A) Alpha hemihydrate B) Betahemihydrate C) Densite D) Plaster of Paris
A) Alpha hemihydrate
All of the following are desired properties of an investment material except:
A) Sufficient strength at room temperature as well as high temperatures
B) Stability at high temperatures
C) Sufficient shrinkage to compensate for expansion that takes place during
casting
D) Thermal expansion that plateaus at casting temperatures
E) Adequateporosity
C) Sufficient shrinkage to compensate for expansion that takes place during casting
Which of the following natural elastomers is used to make Gutta-Percha? A) Cis1,4-polyisoprene B) Trans 1,4-polyisoprene C) Cis 1,4-polystyrene D) Trans 1,4-polystyrene
B) Trans 1,4-polyisoprene
Which of the following impression materials are hydrocolloids? A) Alginate, polysiloxan B) Alginate, agar C) Impression plaster, polysiloxan D) Impression compound only
B) Alginate, agar
What is the reason for setting expansion of gypsum products? A) Highwater/powderratio
B) Chemicaladditives
C) Crystals impinge on one another
D) All of the above
C) Crystals impinge on one another
Which is true regarding phosphate-bonded investments? A) Set by an acid-base reaction B) Are mixed with water only C) Are used for casting gold alloys D) None of the above is true
D) None of the above is true
Which of the following gypsum products require the least amount of excess water? A) TypeI
B) TypeII
C) Type III
D) Type IV
D) Type IV
Why is porosity required to be present in an investment?
A) Allow air/gas enter the mold during casting
B) Allow air/gas to escape during casting
C) Allow quick cooling of the investment mold
D) All mentioned above
B) Allow air/gas to escape during casting
What is the dispersion phase in reversible hydrocolloids? A) Water B) Agar C) Potassium alginate D) Calcium alginate
B) Agar
Which type of gypsum products has the greatest amount of compressive strength? A) Type I B) Type II C) Type III D) Type IV
D) Type IV
What type of investment is used to fabricate removable partial denture framework? A) Gypsumbondedinvestment B) Phosphate bonded investment C) Silicate bonded investment D) Densite based investment
B) Phosphate bonded investment
Two samples of PMMA polymers may have the same chemical structure, but may differ greatly in their physical properties because of the molecular weight components.
A) True
B) False
A) True
Permanent deformation of elastic impression materials is equal to elastic recovery. Permanent deformation is a function of percent compression, time under compression, and time after removal of the compressive load.
A) The first statement is true, but the second statement is false.
B) The first statement is false, but the second statement is true.
C) Both are false
D) Both are true
B) The first statement is false, but the second statement is true.
When calcium sulfate dihydrate mineral is dry heated, it will produce: A) Plasters B) Hydrocal C) Densite D) Plaster of Paris
A) Plasters
Which of the following impression materials set by a physical change? A) Impression compound B) Polysulfide C) Alginate D) Addition Silicones
A) Impression compound
What is the most important manipulative variable with gypsum products? A) Watertemperature B) Water/powder ratio C) Spatulation time D) Vacuum mixing
B) Water/powder ratio
Sulfur contained in latex gloves and powder can inhibit the polymerization of which of the following impression materials: A) Polysufides B) Polyethers C) Addition Silicones D) Condensation silicones
C) Addition Silicones
Which of the following physical processes would lead to expansion of a hydrocolloid impression material? A) Evaporation B) Syneresis C) Imbibition D) Condensation
C) Imbibition
What is the initiator for chemically cured denture resins? A) Benzoyl peroxide B) Camphoroquinone C) Aromatic amines D) Eugenol
A) Benzoyl peroxide
compared to phosphate-bonded investments, gypsum-bonded investments:
A) Set by an acid-base reaction
B) Are mixed with a special liquid
C) Are used for casting high-melting point alloys
D) Are used for casting gold alloys
idk
what is the accelerator for polysufide impression materials? A) Palladium B) Platinum C) Lead dioxide D) Barium
C) Lead dioxide
Which of the following materials sets by a reaction that yields a product that results in the largest dimensional change seen in an elastomeric impression material? A) Polysulfides B) Polyethers C) Addition Silicones D) Condensation Silicones
A) polysulfides
What will happen when the investment is heated in an oven before casting? A) Casting ring will melt B) Casting ring will shrink C) Investment will shrink D) Investment will expand
D) Investment will expand
What is the physical state of a polymer when the room temperature is above its glass transition temperature? A) Rigid and stiff B) Strong and hard C) Soft and weak D) Rubbery
D) Rubbery
What do you expect to happen if you over-mix the alginate impression materials? A) Increasestrength B) Destroy gel fibers C) Increase setting time D) Increase working time E) It has no effect
B) Destroy gel fibers
What is the main constituent of inlay wax? A) Beewax B) Paraffin wax C) Spermaceti wax D) Candelilla wax
B) Paraffin wax
Which of the following is a thermoplastic polymer? A) Polysulfides B) Polyethylene vinyl acetate C) Polypropylene D) Poly methyl methacrylate
B) Polyethylene vinyl acetate
What is the result of increasing the water-powder ratio when mixing gypsum materials? A) Decrease strength of the material B) Increasethesettingtime C) Decrease the setting expansion D) Increase porosity of the set material E) All of the above
E) All of the above
What is the proper amount of time before separating a gypsum cast from an alginate impression? A) 10minutes B) 20minutes C) 30 minutes D) 1 hour E) 24hours
D) 1 hour
