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D1F Operative Dentistry > Biomaterials Final > Flashcards

Biomaterials Final Flashcards

1
Q

3 Main Classes of Materials?

A
  1. Metal
  2. Ceramic
  3. Polymer
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2
Q

Metal Characteristics

A

Hard
Ductile (Tough/Bendable)
Strong

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3
Q

Ceramics Characteristics

A

Hard
Brittle
Strong

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4
Q

Polymers Characteristics

A

Soft
Ductile (Tough/Bendable)
Weak

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5
Q

General Processing Characteristics of:
Metal-
Ceramics-
Polymers-

A

Metal- High temp
Ceramics- High temp
Polymer- low temp, direct processing

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6
Q

Metallic Bond Properties?

A

Electrons are key, they have free mobility

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7
Q

Metal alloys are _____ than pure metal

A

Stronger/Less ductile

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8
Q

Ceramic Bond Characteristics?

A

Ionic and covalent bonds (stronger than metallic); non mobile ions

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9
Q

Most dental ceramics are _____crystalline or ____crystalline

A

Semi

Poly

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10
Q

The building block of Dental Porcelain (ceramics) is _______. It is process by _____ or _____

A

SiO4 tetrahedron

Sintering
Melting at High temps

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11
Q

Polymer Bond Characteristics

A

Covalent bonds; mainly nonmetallic elements; derive strength/properties from entanglement (cooked spaghetti)

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12
Q

Polymerization Process

A
  • Light activation of initiator
  • Initiation of monomer
  • Propagation of free-radical
  • Termination of free-radical
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13
Q

Polymerization can be initiated by?

A

Light
Heat
Chemical mixing

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14
Q

Physical mixtures of metals, ceramics, and/or polymers?

A

Composite

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15
Q

By knowing the phases present in the structure of any material and interfacial interactions, it is possible to predict the overall properties fairly well.

A

Rule of Mixtures

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16
Q

How do fillers affect properties?

A 
Inc Filler vol. ->
Inc Filler Size
Inc Strength
Inc modulus
Inc Viscosity
Inc Surface roughness
Dec shrinkage
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17
Q

Increased LCTE (Linear Coefficient Thermal Expansion) ->

A

Expands/Contracts more w/ temp change

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18
Q

Metal (conductor) near the pulp -> _____ sensitivity, therefore metals need a ______

Composites have ____ thermal conductivity

A

High

Thermal insulator like base

Low

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19
Q

Color has ____ dimensions, they are:

A

3

Hue- wavelength (color)
Value- intensity/brightness
Chroma- purity/density

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20
Q

2 objects that appear the same color under one light source and different under another light source (different spectral characteristics)

A

Metamerism

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21
Q

Linear vs Crosslinked chain:

A

A linear chain (monomethacrylates) grows from one end

A crosslinked chain (dimethacrylates) grows from both ends and makes branches

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22
Q

Mercury Issues with amalgams:
Disposal-
Patient-
Operator-

A

Disposal- ends up in water systems
Patient- poor esthetics
Operator- brittle, sensitive

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23
Q

The tendency of a solid material to deform permanently over time under low constant stresses

A

Creep

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24
Q

Is amalgam ductile or brittle?

A

Ductile

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25
Q

Corrosion of amalgam effects? Corrosion type?

A

Amalgam turns black over time

Electrochemical corrosion (anode and cathode are the two phases)

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26
Q

Major reaction phase in low/high copper amalgam

A

Gamma 1

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27
Q

Does not form with high copper amalgam

A

Gamma 2

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28
Q

High copper alloys have ____ longevity and ____ creep values.

Zn improves _______ and facilitates _____ particles

A

Greater
Lower

Corrosion resistance
Lathe-cut

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29
Q

Setting Reaction: Initially there is _____ due to absorption of _____; then _____ from formation and growth of _____. Final absorption of mercury by remaining amalgam alloy particles causes _____

A

Contraction
Hg

Expansion
Gamma phases

Contraction

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30
Q

_____ is machined from a cast ingot and ____ is molten alloy blown through a nozzle.

______ resists forces of condensation less than _____

_____ is less uniform in size to optimize condensation.

A

Lathe-cut
Spherical

Spherical
Lathe-cut

Lathe cut

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31
Q

First step of setting reaction forms both _____ and _____. Second step shows disappearance of ___

A

Gamma 1
Gamma 2

Gamma 2

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32
Q

Relieves stresses in alloy particles and provides control of setting time. Eliminates compositional no uniformity in ingot before cutting.

A

Heat treatment of alloy

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33
Q

High Contact Angle vs Low Contact Angle

A

High contact angle is poor wetting and hydrophobic

Low contact angle is good wetting and hydrophilic

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34
Q

_____ helps with polymerization of composites while _____ aids in adhering to a surface

A

Hydrophobicity

Hydrophilicity

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35
Q

Electron transfer to allow for oxidation of a metal (corrosion)

A

Electrochemical (Galvanic) corrosion

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36
Q

Two phases (cathode and anode) that go through redox corrosion (amalgam)

A

Structure Selective Corrosion

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37
Q

Crack in the structure -> corrosion

A

Crevice Corrosion

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38
Q

Stress region (anode) and unstressed region (cathode)

A

Stress corrosion

39
Q

Produces corrosion film that prevents further corrosion (implants)

A

Passive

40
Q

What is immune to corrosion?

A

Noble metals (gold)

41
Q

Ceramics degrade by:

A

Hydrolysis (covalent bonds broken down by water)

42
Q

Polymers degrade by:

A

Hydrolysis (absorption of water leads to hydrolysis degradation)

43
Q

Degradation of byproducts can be ____. ____ is a concern of amalgams and ______ is a concern of composites as it is estrogen like.

A

Toxic

Mercury

Bisphenol A

44
Q

Stress limit where material ceases to return to original shape

A

Elastic Limit

45
Q

Point where stress and strain are directly proportional (curve is straight line to this point)

A

Proportional Limit

46
Q

Where material breaks (peak of curve)

A

Ultimate Strength

47
Q

How stiff the material is (greater slope means greater stiffness)

A

Elastic Modulus

48
Q

Curves that tend to be resistant to stress but cannot bear a lot of strain and will break (glass)

A

High elastic modulus

49
Q

Will strain greatly under not much stress (red vine/polymer)

A

Low elastic modulus

50
Q

Able to withstand stress and can strain to support more stress (tootsie roll/metal)

A

Medium elastic modulus

51
Q

The energy absorbed before deformation occurs

A

Modulus (resilience)

52
Q

The energy absorbed before failure/fracture

A

Toughness

53
Q

____ and ____ can cause deformation of a material. ___ can change the setting time of a material.

A

Time
Heat

Heat

54
Q

Ability of a cracked material to resist fracture

A

Fracture toughness

55
Q

Multiple cycles of low stress

A

Fatigue

56
Q

Cusps work as an entity when undergoing ____ forces (high stability), but when a cavity prep takes out the central groove the cups become separate entities subject to fracture.

A

Buccal to Lingual

57
Q

Components of Composite Resins:

A

Organic- Resin -> processing and handling

Inorganic- Filler -> modulus and wear resistance

Coupling/Bonding agent

58
Q

Trade-offs in composite properties:

A

Inorganic- resistant/strong but brittle and poor processing

Polymer- poor resistance but tough and good processing

59
Q

Allows for stronger one unit matrix to be formed

A

Cross linking (curing)

60
Q

Greater crosslink density lead to:

A

Greater strength but more shrinkage

61
Q

High filler loading results in ______. Smaller filler sizes lead to ____.

A

Higher modulus

Better wear properties (for polishing) and better mechanical properties

62
Q

Bind fillers to resin matrix

A

Coupling agents

63
Q

____ results from density change of monomer to polymer. Leads clinically to ____ and ____.

A

Shrinkage

Micro leaks
Secondary caries

64
Q

Glass-ionomer Cement components:

A
  1. Polyacid
  2. Basic glass
  3. Water
  4. Modifiers
65
Q

Glass-Ionomer Cement is cured by ____. This forms ____ bonds which is different different from composites that use ____ bonds.

A

Acid-base rxn

Salt bridge
Covalent

66
Q

The restorative mechanism of Glass-Ionomer Cement requires _____

A

Water

67
Q

Upon setting of Glass-Ionomer Cement, ____ is released and will continue to be released over time.e

A

Fluoride

68
Q

Adhesives are similar to Composites in their _____ chemistry, but are different because they are _____

A

Resin

Unfilled/Lightly filled

69
Q

Sealants differ from composites because they attach through ____ means rather than ____ means and they usually lack a ____.

A

Mechanical

Chemical

Filler

70
Q

Area where oxygen interferes with radical polymerization at the surface leaving a thin layer often uncured

A

Oxygen inhibition layer

71
Q

Polysulfied (good detail) impression material

A

Elastomer Impression Material

72
Q

Alginate (not as accurate) impression material

A

Hydrocolloid impression material

73
Q

Ideal Properties of Impression Materials:

A
  • Low cost
  • Long shelf life
  • biocompatible
  • pleasant
  • stable
  • good handling properties
74
Q

Pros and Cons of Water based alginates

A

Pros- economical, easy, fast, taste, hydrophilic

Cons- dimensional instability, low tear resistance, limited details, single pour only, quick pour required

75
Q

Undergoes shrinkage/expansion upon water loss/gain

A

Dimensional Stability

76
Q

_____ are hydrophobic -> better stability for impressions

But _______ can turn this material to hydrophilic

A

Polysiloxanes

Surfactants

77
Q

Is also hydrophobic but has better surface characteristics than Polysiloxanes. Also has good dimensional stability.

A

Polyethers

78
Q

___ is used to make casts. It is cured by ____.

When mixed with this curing agent, it is _____ and creates a ____ again (heat is released)

Properties are dependent on ____ structure and ____

A

Gypsum
Water

Rehydrated
Dehydrate

Crystal
Density

79
Q

Dental _____ (not plaster) is used for models

A

Stone

80
Q

Denture base is normally _____

A

VLC

81
Q

Provisionals are normally ____ cured

A

Chemically

82
Q

Mouth guards are _____ instead of thermoset (low softening point) and properties are controlled by a _____

A

Thermoplastic

Copolymer

83
Q

Used to bind restoration of appliances to tooth structure

A

Cements

84
Q

Requirements for cements

A

Low viscosity with good mechanical properties

85
Q

_____ ratio modifies the viscosity and handling properties of cement.

A

Powder-to-liquid

86
Q

More filler (powder) leads to a more ____ and ____ cement.

Less powder increases _____.

A

Viscosity
Modulus

Working and setting time

87
Q

Cement type used for ortho, crowns, bridges, veneers. Similar chemistry to composite

A

Resin Cements

88
Q

Two component cement type where you mix the liquid and powder

A

Glass Ionomer

89
Q

Used to protect dentin from residual reactants that can diffuse out of the restoration/fluids that may leak in from the oral cavity; near pulp exposure

A

Liners

90
Q

Used to provide thermal protection for pulp and mechanical support to resoration

A

Bases

91
Q

Near or direct pulp exposure, use CALCIUM HYDROXIDE to initiate reparative dentin formation

A

Pulp Capping

92
Q

Used as a sedative restoration (pain reduction)

A

Zinc Oxide and Eugenol (ZOE)

93
Q

_____ should melt at low temps, be carve-able, burn off, and be dimensionally stable. They are lower molecular weight materials in between ____ and _____

A

Waxes

Polymers
Organic Liquids

94
Q

Thermal Expansion coefficient relations between tooth, amalgam, and composite

A

Composite (Polymer) > Amalgam (Metal) > Tooth (and Ceramic)

D1F Operative Dentistry (5 decks)

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