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89 Cards in this Set
- Front
- Back
How can you distinguish between a tooth ache and dentin sensitivity?
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Dentin sensitivity is caused by a stimulus and pain ceases when stimulus is taken away. Tooth ace is constant pain not associated with a particular stimulus
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What can cause pulpal inflamation?
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Open tubules and bacteria, traumatic occlusion, and abrasion/erosion
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What is the most common location of dentin sensitivity?
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Buccal surfaces of posterior teeth, but it can occur anywhere.
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What is the active ingredient in sensitivity toothpastes?
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5% potassium nitrate
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How does oxylate precipitation help sensitivity?
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It combines with calcium to precipitate calcium oxylate that occludes open dentinal tubules
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What is the common main ingredient in dentin bonding agents used to tx sensitivity?
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HEMA, its used as a protein precipitating agent to occlude tubules
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What is ionophoresis?
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Electrical current applied to the tooth with flouride solution to enhance ion uptake by dentinal tubules
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What is the most commonly used polymer in denture bases?
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Poly methyl methacrylate
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What kind of material is PMMA?
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It is a high impact, heat cured acrylic. It's the most popular material
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What is done to reduce polymerization shrinkage in PMMA used for denture base?
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It has pre-polymerized PMMA beads in it
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What is the initiator used in most denture polymers?
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Benzoyle peroxide, activated with heat
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What property do plasticizers give to denture base polymer?
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They make it softer (less brittle) than pure polymer slone
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What cross linking agents are commonly used in denture base polymers?
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Ethylene glycol dimethacrylate (EGDMA)
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Is PMMA formed by condensation or addition polymerization?
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Free-radical addition rxn
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What are the physical properties of acrylic denture resin?
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Low strength, fairly flexible, and brittle on impact
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Why is it a bad idea to boil dentures to clean them?
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Because the heat distortion temp is low (71-91 C) and it has a high CTE so the porcelain teeth may fall out when acrylic expands
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What is the actual shrinkage of acrylic resin?
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Would be 6-7% but since its in a mold usually it is limited to 0.2-0.5%
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What effect does repeated wetting and drying of dentures have?
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May cause warpage or cracking, due to high water sorption or material. You should just keep them moist.
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T/F Adhesion of acrylic to porcelain or metals is generally good
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Flase, its poor unless its treated with silane or etched.
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What is generally the cause of alergic rxn to denture acrylic?
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Usually due to unreacted monomer or other components that are leaching out. Polymerized acrylic is biocompatible
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Why is PMMA reinforced with rubber in some cases?
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Because the dispersed rubber phase leads to greater impact strength.
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How are chemical cured PMMA's initiated to polymerize?
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They have a tertiary amine that reacts with benzoyl peroxide to form the free radical. No heat needed
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What effect do amine accelerators have on acylics?
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They lead to color instability. Dentures will turn yellow with age
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When would you use chemical cured acrylic?
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Usually for repairs or relines. You would use heat-cured otherwise cause its stronger
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What is the next best alternative to PMMA?
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Polyvinyl acrylics. They are les brittle and are good to use in pts allergic to PMMA
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Which denture base acrylic do we use at UNLV?
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Lucitone 199
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What kind of strength can you expect when you repair a broken denture?
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About 60% of the original strength
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What problems to acrylic soft lining materials have?
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They have a high amount of plasitcizer that leach out, and they don't adhere to the base very well.
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What is the current gold standard for soft-lining denture materials?
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Silicone materials
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Which occlusal splint materials are softer inside and easier to fit?
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Brux-eze and Rem-e-deze
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T/F Any metal can be used in a PFM crown
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False, not all metals can bond chemically and there is temp incompatibility between many metals and ceramics
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T/F Metals used in PFM's could also be used to make a full metal crown
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True
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What is ductility?
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The degree to which a material can be permanently deformed by a tensile force without fracturing
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What are the noble metals?
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Gold, platinum, and palladium
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How are restorative alloys classified?
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By composition (noble level) and properties (strength, CTE, hardness, etc)
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What is the most dense of the noble metals?
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Platinum, followed closely by gold, then palladium
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T/F Less dense metals are less castable
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True
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Which noble metal has a CTE closest to tooth?
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Gold, at 18 (tooth is 9-11)
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What is the composition of high noble alloys?
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Must have at least 60% noble metal content or 40% gold content by weight
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What is the composition of noble alloys?
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Contains at least 25% noble metals by weight
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What is the composition of base-metal alloys?
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Less than 25% noble metal content by weight
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Which metal is precious but not noble and why?
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Silver, its precious because it valuable but not noble because it corrodes easily
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What are the disadvantages of high noble alloys?
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They have less strength, stiffness, and hardness than many alloys
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What type of alloy is most commonly used at UNLV?
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Noble type 3 metals, ie Argenco 20
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Which metal in base-metal alloys can cause allergy?
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Nickel
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Which method of ceramo-metal crown fabrication requires casting the metal coping?
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PFM done by lost wax technique
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How is the ceramic bonded to the metal coping in a PFM?
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52% chemical bond, 22% mechanical, and 26% compression
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How does the metal chemically bond to porcelain in PFM?
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The metal oxide layer bonds to the silica in the porcelain
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What is the max difference in CTE allowed for a PFM?
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It shouldn't be more than 1ppm. Usually ceramic is about 13.5 and alloys are 14.3
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What are added to porcelain to adjust the CTE?
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Metal oxides. They interrupt the silica crystal lattice and reduce bond strength.
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Which metal used in alloys can stain ceramics?
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Silver (Ag)
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When would you opt to use a base-metal alloy?
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For thinner castings and long-span bridges or if cost is an issue
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What metals contribute most to color of alloys?
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Gold will usually make it more yellow, palladium will make it more white
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What is the biggest contributor to environmental mercury release?
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Human activity, mostly the burning of fossil fuels
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What are the inorganic and organic compounds of mercury?
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Cinnabar is the inorganic and dimethyl mercury is the organic compound
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What are the absorption routes of the different forms of mercury?
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Inorganic mostly absorbed by lungs, little in GI. Organic mostly by GI tract, and elemental mostly by lungs. Skin doesn't really absorb any.
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How is organic mercury made?
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By microorganisms converting inorganic and elemental mercury into methyl mercury
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What are symptoms of mercury esposure?
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Headache, nausea, diarrhea, depression, insomnia, tremors or convulsions, etc
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What is the main area of the body that Hg will accumulate?
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In the central nervous system. The average half life is 55 days
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What causes Minamata's disease?
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Hg toxicity
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What are the OSHA standards for mercury vapor levels?
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0.1 mg/m3 Hg averaged over 8 hours
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What is the lower limit of Hg conc in the urine that will still cause health effects?
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25ug per gram creatinine
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How efficient are amalgam traps at removing particles from waste water?
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Generally about 40-80% removal of Hg particles
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Which ISO standard has to do with removal of amalgam from air/water systems?
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ISO 1143 for amalgam separators. States that separators must have at least 95% removal efficiency
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T/F Extracted teeth with amalgam restorations should not be placed with biohazard waste that will be incinerated
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True
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What types of line cleaners do you want to avoid in order to minimize amalgam dissolution?
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Non-bleach, non-chlorine containing line cleaners
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What are the 3 liquids used in traditional acid-base cements?
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Phosphoric acid, eugenol, and polyacrylic acid
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What are the two powders used in traditional acid-base cements?
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Zinc oxide and CaFAlSiO2 glass
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Which cement has a neutral pH and is therefore soothing to the pulp?
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Zinc oxide eugenol (ZOE)
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Which acid-base cements can chemically bond to the tooth?
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Zinc polycarboxylate and glass ionomer
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Which RMGI luting cement is used at UNLV?
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FujiCEM, chemical-cured
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What are the advantages of RMGI over refular GI?
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More resistant to moisture contamination and stronger
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When is the use of eugenol containing cements contraindicated as a temp cement?
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If your going to use a dentin bonding agent or resin-based cement on the permanent restoration. Eugenol interferes with polymerization
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Which two zinco oxide eugenol cements are used at UNLV?
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IRM and TempBond
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What is TempBond NE?
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It means no eugenol, used in cases where you are going to use resin cement for permanent restoration
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What do you need to mix with zinc polycarboxylate cement if you want to use it as a temp cement?
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You mix it with vasoline to prevent bonding to tooth
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Which zinc polycarboxylate cement is used at UNLV?
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Durelon
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Which cement would you use as a temporary cement if you are near the pulp?
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Calcium hydroxide (Dycal)
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What type of temp cement would you use on teeth prepped with little retention?
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Resin-based cements like Temp-Bond clear and SensiTemp
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T/F Light cured resin cements are less color stable than chemical cured
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False, light cured is more color stable
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How much expansion does it take to fracture an all ceramic crown?
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4% expansion
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What is the dark blue amalgam capsule?
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2 spill regular set Dispersalloy admixed amalgam. Mix for 11-17s
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What is the yellow amalgam capsule?
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3 spill regular-set Dispersalloy admixed amalgam. Mix for 10-14s
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What is the yellow and white amalgam capsule?
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3 spill fast-set Dispersalloy admixed amalgam. Mix for 10-14s
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What is the aqua and gray amalgam?
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2 spill Ionosphere admixed amalgam. Mix for 8-12s
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What is the aqua amalgam capsule?
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3 spill Ionosphere admixed amalgam. Mix for 12-16s
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What is the thickness of a regular Toffelmire band?
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0.002 inch
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What is the thickness of a dead-soft Toffelmire band?
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0.001 inch
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What is the thickness of a SuperMat matrix band?
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0.0012 inch
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