Dental Materials Final

Front 1

How can you distinguish between a tooth ache and dentin sensitivity?

Back 1

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

Front 2

What can cause pulpal inflamation?

Back 2

Open tubules and bacteria, traumatic occlusion, and abrasion/erosion

Front 3

What is the most common location of dentin sensitivity?

Back 3

Buccal surfaces of posterior teeth, but it can occur anywhere.

Front 4

What is the active ingredient in sensitivity toothpastes?

Back 4

5% potassium nitrate

Front 5

How does oxylate precipitation help sensitivity?

Back 5

It combines with calcium to precipitate calcium oxylate that occludes open dentinal tubules

Front 6

What is the common main ingredient in dentin bonding agents used to tx sensitivity?

Back 6

HEMA, its used as a protein precipitating agent to occlude tubules

Front 7

What is ionophoresis?

Back 7

Electrical current applied to the tooth with flouride solution to enhance ion uptake by dentinal tubules

Front 8

What is the most commonly used polymer in denture bases?

Back 8

Poly methyl methacrylate

Front 9

What kind of material is PMMA?

Back 9

It is a high impact, heat cured acrylic. It's the most popular material

Front 10

What is done to reduce polymerization shrinkage in PMMA used for denture base?

Back 10

It has pre-polymerized PMMA beads in it

Front 11

What is the initiator used in most denture polymers?

Back 11

Benzoyle peroxide, activated with heat

Front 12

What property do plasticizers give to denture base polymer?

Back 12

They make it softer (less brittle) than pure polymer slone

Front 13

What cross linking agents are commonly used in denture base polymers?

Back 13

Ethylene glycol dimethacrylate (EGDMA)

Front 14

Is PMMA formed by condensation or addition polymerization?

Back 14

Free-radical addition rxn

Front 15

What are the physical properties of acrylic denture resin?

Back 15

Low strength, fairly flexible, and brittle on impact

Front 16

Why is it a bad idea to boil dentures to clean them?

Back 16

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

Front 17

What is the actual shrinkage of acrylic resin?

Back 17

Would be 6-7% but since its in a mold usually it is limited to 0.2-0.5%

Front 18

What effect does repeated wetting and drying of dentures have?

Back 18

May cause warpage or cracking, due to high water sorption or material. You should just keep them moist.

Front 19

T/F Adhesion of acrylic to porcelain or metals is generally good

Back 19

Flase, its poor unless its treated with silane or etched.

Front 20

What is generally the cause of alergic rxn to denture acrylic?

Back 20

Usually due to unreacted monomer or other components that are leaching out. Polymerized acrylic is biocompatible

Front 21

Why is PMMA reinforced with rubber in some cases?

Back 21

Because the dispersed rubber phase leads to greater impact strength.

Front 22

How are chemical cured PMMA's initiated to polymerize?

Back 22

They have a tertiary amine that reacts with benzoyl peroxide to form the free radical. No heat needed

Front 23

What effect do amine accelerators have on acylics?

Back 23

They lead to color instability. Dentures will turn yellow with age

Front 24

When would you use chemical cured acrylic?

Back 24

Usually for repairs or relines. You would use heat-cured otherwise cause its stronger

Front 25

What is the next best alternative to PMMA?

Back 25

Polyvinyl acrylics. They are les brittle and are good to use in pts allergic to PMMA

Front 26

Which denture base acrylic do we use at UNLV?

Back 26

Lucitone 199

Front 27

What kind of strength can you expect when you repair a broken denture?

Back 27

About 60% of the original strength

Front 28

What problems to acrylic soft lining materials have?

Back 28

They have a high amount of plasitcizer that leach out, and they don't adhere to the base very well.

Front 29

What is the current gold standard for soft-lining denture materials?

Back 29

Silicone materials

Front 30

Which occlusal splint materials are softer inside and easier to fit?

Back 30

Brux-eze and Rem-e-deze

Front 31

T/F Any metal can be used in a PFM crown

Back 31

False, not all metals can bond chemically and there is temp incompatibility between many metals and ceramics

Front 32

T/F Metals used in PFM's could also be used to make a full metal crown

Back 32

True

Front 33

What is ductility?

Back 33

The degree to which a material can be permanently deformed by a tensile force without fracturing

Front 34

What are the noble metals?

Back 34

Gold, platinum, and palladium

Front 35

How are restorative alloys classified?

Back 35

By composition (noble level) and properties (strength, CTE, hardness, etc)

Front 36

What is the most dense of the noble metals?

Back 36

Platinum, followed closely by gold, then palladium

Front 37

T/F Less dense metals are less castable

Back 37

True

Front 38

Which noble metal has a CTE closest to tooth?

Back 38

Gold, at 18 (tooth is 9-11)

Front 39

What is the composition of high noble alloys?

Back 39

Must have at least 60% noble metal content or 40% gold content by weight

Front 40

What is the composition of noble alloys?

Back 40

Contains at least 25% noble metals by weight

Front 41

What is the composition of base-metal alloys?

Back 41

Less than 25% noble metal content by weight

Front 42

Which metal is precious but not noble and why?

Back 42

Silver, its precious because it valuable but not noble because it corrodes easily

Front 43

What are the disadvantages of high noble alloys?

Back 43

They have less strength, stiffness, and hardness than many alloys

Front 44

What type of alloy is most commonly used at UNLV?

Back 44

Noble type 3 metals, ie Argenco 20

Front 45

Which metal in base-metal alloys can cause allergy?

Back 45

Nickel

Front 46

Which method of ceramo-metal crown fabrication requires casting the metal coping?

Back 46

PFM done by lost wax technique

Front 47

How is the ceramic bonded to the metal coping in a PFM?

Back 47

52% chemical bond, 22% mechanical, and 26% compression

Front 48

How does the metal chemically bond to porcelain in PFM?

Back 48

The metal oxide layer bonds to the silica in the porcelain

Front 49

What is the max difference in CTE allowed for a PFM?

Back 49

It shouldn't be more than 1ppm. Usually ceramic is about 13.5 and alloys are 14.3

Front 50

What are added to porcelain to adjust the CTE?

Back 50

Metal oxides. They interrupt the silica crystal lattice and reduce bond strength.

Front 51

Which metal used in alloys can stain ceramics?

Back 51

Silver (Ag)

Front 52

When would you opt to use a base-metal alloy?

Back 52

For thinner castings and long-span bridges or if cost is an issue

Front 53

What metals contribute most to color of alloys?

Back 53

Gold will usually make it more yellow, palladium will make it more white

Front 54

What is the biggest contributor to environmental mercury release?

Back 54

Human activity, mostly the burning of fossil fuels

Front 55

What are the inorganic and organic compounds of mercury?

Back 55

Cinnabar is the inorganic and dimethyl mercury is the organic compound

Front 56

What are the absorption routes of the different forms of mercury?

Back 56

Inorganic mostly absorbed by lungs, little in GI. Organic mostly by GI tract, and elemental mostly by lungs. Skin doesn't really absorb any.

Front 57

How is organic mercury made?

Back 57

By microorganisms converting inorganic and elemental mercury into methyl mercury

Front 58

What are symptoms of mercury esposure?

Back 58

Headache, nausea, diarrhea, depression, insomnia, tremors or convulsions, etc

Front 59

What is the main area of the body that Hg will accumulate?

Back 59

In the central nervous system. The average half life is 55 days

Front 60

What causes Minamata's disease?

Back 60

Hg toxicity

Front 61

What are the OSHA standards for mercury vapor levels?

Back 61

0.1 mg/m3 Hg averaged over 8 hours

Front 62

What is the lower limit of Hg conc in the urine that will still cause health effects?

Back 62

25ug per gram creatinine

Front 63

How efficient are amalgam traps at removing particles from waste water?

Back 63

Generally about 40-80% removal of Hg particles

Front 64

Which ISO standard has to do with removal of amalgam from air/water systems?

Back 64

ISO 1143 for amalgam separators. States that separators must have at least 95% removal efficiency

Front 65

T/F Extracted teeth with amalgam restorations should not be placed with biohazard waste that will be incinerated

Back 65

True

Front 66

What types of line cleaners do you want to avoid in order to minimize amalgam dissolution?

Back 66

Non-bleach, non-chlorine containing line cleaners

Front 67

What are the 3 liquids used in traditional acid-base cements?

Back 67

Phosphoric acid, eugenol, and polyacrylic acid

Front 68

What are the two powders used in traditional acid-base cements?

Back 68

Zinc oxide and CaFAlSiO2 glass

Front 69

Which cement has a neutral pH and is therefore soothing to the pulp?

Back 69

Zinc oxide eugenol (ZOE)

Front 70

Which acid-base cements can chemically bond to the tooth?

Back 70

Zinc polycarboxylate and glass ionomer

Front 71

Which RMGI luting cement is used at UNLV?

Back 71

FujiCEM, chemical-cured

Front 72

What are the advantages of RMGI over refular GI?

Back 72

More resistant to moisture contamination and stronger

Front 73

When is the use of eugenol containing cements contraindicated as a temp cement?

Back 73

If your going to use a dentin bonding agent or resin-based cement on the permanent restoration. Eugenol interferes with polymerization

Front 74

Which two zinco oxide eugenol cements are used at UNLV?

Back 74

IRM and TempBond

Front 75

What is TempBond NE?

Back 75

It means no eugenol, used in cases where you are going to use resin cement for permanent restoration

Front 76

What do you need to mix with zinc polycarboxylate cement if you want to use it as a temp cement?

Back 76

You mix it with vasoline to prevent bonding to tooth

Front 77

Which zinc polycarboxylate cement is used at UNLV?

Back 77

Durelon

Front 78

Which cement would you use as a temporary cement if you are near the pulp?

Back 78

Calcium hydroxide (Dycal)

Front 79

What type of temp cement would you use on teeth prepped with little retention?

Back 79

Resin-based cements like Temp-Bond clear and SensiTemp

Front 80

T/F Light cured resin cements are less color stable than chemical cured

Back 80

False, light cured is more color stable

Front 81

How much expansion does it take to fracture an all ceramic crown?

Back 81

4% expansion

Front 82

What is the dark blue amalgam capsule?

Back 82

2 spill regular set Dispersalloy admixed amalgam. Mix for 11-17s

Front 83

What is the yellow amalgam capsule?

Back 83

3 spill regular-set Dispersalloy admixed amalgam. Mix for 10-14s

Front 84

What is the yellow and white amalgam capsule?

Back 84

3 spill fast-set Dispersalloy admixed amalgam. Mix for 10-14s

Front 85

What is the aqua and gray amalgam?

Back 85

2 spill Ionosphere admixed amalgam. Mix for 8-12s

Front 86

What is the aqua amalgam capsule?

Back 86

3 spill Ionosphere admixed amalgam. Mix for 12-16s

Front 87

What is the thickness of a regular Toffelmire band?

Back 87

0.002 inch

Front 88

What is the thickness of a dead-soft Toffelmire band?

Back 88

0.001 inch

Front 89

What is the thickness of a SuperMat matrix band?

Back 89

0.0012 inch