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Tim's Cards > Dental Materials Part II, Test II > Flashcards

Dental Materials Part II, Test II Flashcards

1
Q

Name 4 advantages to Glass Ionomers

A

Inherent (chemical) adhesion to tooth

Fluoride release

CTE - Coefficient of thermal expansion is similar to tooth

Biocompatible

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2
Q

What does RMGI stand for?

What are 2 important characteristics of RMGI?

A

Resin-modified Glass Ionomer

Acid-base rxn

light and/or chemical cure

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3
Q

What are the 3 phases of the Conventional Setting Reaction in Glass Ionomers?

A

Ion-leaching

Hydrogel

Polysalt-Gel

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4
Q

What is formed in the Ion-Leaching phase of a conventional setting rxn for Glass Ionomers?

Name 2 importanat characteristics of this product:

A

NaF

Not native to Matrix

Physical properties aren’t affected by depletion

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5
Q

What are the 2 types of rxn going on in the Setting of RMGI?

A

Acid-Base Rxn - traditional glass-ionomer
(proceeds more slowly)

Free-radical polymerization
(similar to composites - light/chemical initiated)

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6
Q

What are 3 properties of the Fluoride Release from Glass Ionomers?

A

Rapid Early

Slow, long term

Doesn’t affect physical properties (also doesn’t take part in matrix formation)

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7
Q

How long does the initial burst of Fluoride Release from Glass Ionomers last?

A

1-2 Days

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8
Q

The uptake and re-release process process that maintains Fluoride reservoirs can be supplemented with what?

A

Topical fluorides

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9
Q

In a glass ionomer, the Fluoride reservoir in the reservoir is _____ the initial burst.

A

A fraction of

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10
Q

What type of restoration cannot be used with RMGI - Resin Modified Glass Ionomers?

A

Non-Reinforced All-Ceramics

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11
Q

2 examples of an Elastic Impression Material:

What type are they?

A

Agar and Aginate

Aqueous hydrocolloids

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12
Q

Describe the Syneresis process that occurs with Aqueous Hydrocolloids:
(3 things)

A

Fibril cross linking

Contracts

Exudes water

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13
Q

What is the primary disadvantage to Alginate?

A

Single cast only

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14
Q

What are the Advnatages to Addition Silicones?

A

Multiple casts

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15
Q

How does Polyether compare in stiffness to Addition Silicone?

A

Polyether > Addition Sillicone

*Polyether is the most rigid

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16
Q

List 5 Impression materials from the most to least rigid:

A

Polyether > Addition Silicone > Condensation Silicone > Polysulfide = Hydrocolloids

*Polyether most difficult to get out of pt’s mouth

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17
Q

Why Amalgam? - 5 reasons

A

Inexpensive

Easy to use

Proven (more than 100 years)

Familiarity

Resin-free (less allergies than composite)

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18
Q

What are 2 important functions of Cu in Amalgam?

A

Ties up tin by reducing Gamma-2 formation

Reduces creep by reducing marginal deterioration

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19
Q

What does Zinc do for the other elements in Amalgam?

*How?

A

Decreases oxidation

*by sacrificial anode

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20
Q

If Amalgam is a brick wall, what fills the holes/voids of the cement?

A

Sn8Hg - Gamma 2

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21
Q

In an admixed high-copper alloy, what is added to the eutectic?

A

Copper

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22
Q

Gamma 1:

A

Ag2Hg3

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23
Q 
T/F
Gamma 1 (Ag2Hg3) surrounds eta phase (Cu6Sn5) and gamma alloy particles (Ag3Sn)
A

True

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24
Q 
T/F
Gamma sphere (Ag3Sn) with epsilon coating (Cu3Sn)

Ag and Sn dissolve in Hg

A

True

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25
Formula for Single Composition High-Copper Alloys
Ag3Sn + Cu3Sn + Hg > Ag3Sn + Cu3Sn + Ag2Hg3 + Cu6Sn5
26
In the SCS - Single Composition Spherical method of adding Copper to Amalgam, the less the condensation force, the ________.
Larger the Condenser
27
T/F | Most high-copper amalgams undergo a net contraction
True
28
What do high-copper amalgams leave once they have contracted? What does this cause?
Marginal gap Initial leakage and post-op sensitivity
29
T/F | High-copper amalgams will have reduced corrosion over time
True
30
What does the net contraction of Amalgams depend on? | 3 things
Type of alloy Condensation technique Trituration time
31
What type of alloy has more contraction?
Spherical | less mercury
32
Greater condensation =
Higher contraction
33
What does overtitration cause in an amalgam?
Higher contraction
34
What type of Strength do amalgams have?
Higher compressive vs. Tensile
35
T/F | Corrosion reduces strength of Amalgam
True
36
What are the 2 ways Corrosion will seal margins Low copper? High copper?
Low Cu: 6 months (SnO2, SnCl - gamma 2 phase) High Cu: 6-24 months (SnO2, SnCl, CuCl - eta-phase Cu6Sn5)
37
Creep correlates with what?
Marginal Breakdown
38
How much Cu must be in amalgam before it can preven the Gamma-2 phase and have Creep Resistance?
12% Cu total
39
Overtrituration will have what 3 effects?
"hot" mix - sticks to capsule Decreases working/setting time Increases setting contraction
40
Undertituration will create what kind of mix?
Grainy, crumbly
41
What does Condensation of Amalgam do to Hg?
Reduces residual Hg in restoration ***this is what happens when packing preparation
42
``` T/F Condensation is: A continuation of trituration Adapts amalgam to cavity walls REduces residual Hg in restoration Eliminated voids Increases strength and servicability to restoration ```
True
43
T/F Dentists can specialize in treating purported Hg toxicity, and the removal of amalgam supposedly cures Leukemia, Hodgkin's disease, and MS
True
44
T/F | The lay population is unfamiliar with peer reviewed dental lit and relies on media/internet to get it right
True
45
How many Amalgam Restorations are there/yr?
1/2 Billion *75 tons of Hg
46
T/F | Mercury vapor is released by chewing/brushing and it is difficult to determine vapor levels accurately
True
47
What is the average daily dose of Mercury from 8-10 amalgam surfaces? What is the threshold level?
1-2 micrograms/day 50 micrograms/day 82 considered dangerous
48
Less than _____ % of elemental Mercury can be absorbed from the GI and the skin
0. 1% | * also non-toxic if swallowed
49
T/F | Mercury vapor from spills (thermometers, fluorescent light bulbs) accountf for most exposure
True
50
What is the most toxic form of Mercury? Where is it absorbed?
Methylated 95% absorbed in gut *Minamata Bay - Hg methylated by marine animals and concentrated up food chain
51
Blood can reflect ______ of Hg
Recent exposure
52
What is the half life of Hg in the blood
3 day
53
T/F | Hair is a reliable method for Hg monitoring
False
54
T/F | Studies found no relationship between Amalgam and MS
True
55
T/F | Studies have linked Hg from amalgam Hg to Hg found in Alzheimersf
False *no link established
56
T/F | Studie show Renal Toxicity due to Amalgam restorations
False
57
T/F Changing the Powder/Liquid ration will have a profound effect on Film Thickness and Consistency when it comes to cements, liners, and bases
True
58
What determines the Ultimate Film Thickness in Cements? 5 components
Particle size of powder Conc. powder in liquid Liquid viscosity Cement consistency Force applied at cementation
59
What 2 factors influence the ease with which cement is expressed from under the restoration?
Consistency of cement Type of restoration
60
T/F | Self etching has no Etch and Rinse - all 3 components, the Etch, Primer, and Bonding Agent are combined
True
61
T/F | Etch and Rinse are generally 3 step or 2 step process
True
62
A 3 Step Etch and Rinse would be a ______ Generation
4th 1 - etch and Rinse 2 - Primer 3 - Bonding/Adhesive agent
63
5th Generation 2 step has what 2 steps?
1 - Etch and Rinse 2 - Primer/Adhesive mixture
64
T/F | Self-etching can be 1 or 2 steps
True
65
Self Etching: conditioner, etch, and primer all mixed and either 1: or 2:
1: Bonding incorporated (1 step) 2: Etch and Primer mixed, Then mix Adhesive (2 steps)
66
With the exception of _________, most bonding is _______
Glass-ionomer Micro-mechanical
67
Bonding to dentin locks into micropores created when etched - collagen fibers and dentinal tubules
True
68
Most anything bad about restorations is due to amount of polymer
True
69
More fillers, less matrix Less fillers, more matrix
Microhybrid Microfill
70
Biggest problem with polymerization shrinkage?
Bond failure at Interface
71
Gamma: Gamma 1: Gamma 2:
Ag3Sn (bricks) Ag2Hg3 (cement) Sn8Hg (void filler in cement)
72
Cu added to Epsilon by: Cu added to Silver-copper eutectic by:
Gamma (Ag3Sn), Ag and Sn dissolve in Hg Spherical - Ag enters Hg from Ag-Cu spherical eutectic particles
73
Urine Hg testing for: Blood Hg testing for:
chronic acute
74
Composites, Cu ionomers, Glassionomers, RMGI which has the most F?
Similar for Conventional Glass-Ionomers and RMGI
75
T/F Higher conc. of Cu reduces the Gamma-2 formation that reduces creep and corrosion and doesn't react with Hg because it attracts tin
True
76
Which phase of amalgam is the weakest?
Gamma 2

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