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89 Cards in this Set

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