Dental Materials Part II, Test II Flashcards Preview

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Flashcards in Dental Materials Part II, Test II Deck (76):
1

Name 4 advantages to Glass Ionomers

Inherent (chemical) adhesion to tooth

Fluoride release

CTE - Coefficient of thermal expansion is similar to tooth

Biocompatible

2

What does RMGI stand for?

What are 2 important characteristics of RMGI?

Resin-modified Glass Ionomer

Acid-base rxn

light and/or chemical cure

3

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

Ion-leaching

Hydrogel

Polysalt-Gel

4

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

Name 2 importanat characteristics of this product:

NaF

Not native to Matrix

Physical properties aren't affected by depletion

5

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

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

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

6

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

Rapid Early

Slow, long term

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

7

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

1-2 Days

8

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

Topical fluorides

9

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

A fraction of

10

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

Non-Reinforced All-Ceramics

11

2 examples of an Elastic Impression Material:

What type are they?

Agar and Aginate

Aqueous hydrocolloids

12

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

Fibril cross linking

Contracts

Exudes water

13

What is the primary disadvantage to Alginate?

Single cast only

14

What are the Advnatages to Addition Silicones?

Multiple casts

15

How does Polyether compare in stiffness to Addition Silicone?

Polyether > Addition Sillicone

*Polyether is the most rigid

16

List 5 Impression materials from the most to least rigid:

Polyether > Addition Silicone > Condensation Silicone > Polysulfide = Hydrocolloids

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

17

Why Amalgam? - 5 reasons

Inexpensive

Easy to use

Proven (more than 100 years)

Familiarity

Resin-free (less allergies than composite)

18

What are 2 important functions of Cu in Amalgam?

Ties up tin by reducing Gamma-2 formation

Reduces creep by reducing marginal deterioration

19

What does Zinc do for the other elements in Amalgam?

*How?

Decreases oxidation

*by sacrificial anode

20

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

Sn8Hg - Gamma 2

21

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

Copper

22

Gamma 1:

Ag2Hg3

23

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

True

24

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

Ag and Sn dissolve in Hg

True

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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