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Dental Materials > Introduction > Flashcards

Introduction Flashcards

1
Q

What are the material categories?

A

Composite, ceramic, metal, and polymer

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2
Q

What kind of material are composite resin and glass-ionomer?

A

Polymer-ceramic

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3
Q

Are there metal-polymers in dentistry?

A

No

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4
Q

How are dental materials characterized?

A

By the structure, properties, applicability, requirements, aesthetics, handling properties, and patient satisfaction

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5
Q

What are examples of suboptimal materials used early in history?

A

Copper, tin, bronze, and gold

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6
Q

What are materials used to construct artificial organs, rehabilitation devices, or prostheses and replace natural body tissue?

A

Biomaterials

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7
Q

Can bio materials cause harm or a negative reaction?

A

No

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8
Q

What are examples of synthetic biomaterials

A

Composites and silicone impression material

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9
Q

What are examples of natural biomaterials

A

Alginate and hydrocolloids

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10
Q

What are examples of tissue-engineered biomaterials

A

Stem cells, replacement tissues (grow tooth from bud)

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11
Q

Properties of metal

A

Hard, ductile (bend w/o breaking), strong

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12
Q

Properties of ceramics

A

Hard, brittle, strong

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13
Q

Properties of polymers

A

Soft, ductile, weak

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14
Q

Which materials have high processing temperatures?

A

Metals and ceramics

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15
Q

Which material has a lower processing temperature?

A

Polymers

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16
Q

Which material tend to be used as direct process materials?

A

Polymers

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17
Q

How are metals used in dentistry?

A

Cast metal crowns, implants, metal-ceramic crowns, endo treated teeth

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18
Q

How many electrons do metallic elements have in their outer shell?

A

1-3

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19
Q

Are electrons tightly or loosely bound to the nucleus in a metal bond?

A

loose

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20
Q

What does is mean that electrons have free mobility in metallic bonds?

A

thermal and electrical conductivity, ductility-bend without breaking

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21
Q

What is the microstructure of metals?

A

polycrystalline structures - single phase-single composition

formation of grains upon cooling

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22
Q

How many metals are mixed in metal alloys?

A

Two or more

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23
Q

Where are metal alloys used in dentistry?

A

cast crowns and amalgam fillings

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24
Q

Are metal alloys more or less ductile?

A

Less ductile and stronger (resists forces)

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25
Q

Why are noble metals used?

A

To resist reformation and impede dislocations

AKA makes defects less prone to failure

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26
Q

What are examples are solid solution hardening metals?

A

Gold, silver, palladium, and platinum

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27
Q

True or False

The larger the grain size of the metal, the better the mechanical properties?

A

False

The smaller the grain size the better the mechanical properties

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28
Q

What is the microstructure of ceramic?

A

crystalline (long range order) or noncrystalline (short rang or no long range)

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29
Q

What is the microstructure of most dental ceramics?

A

semicrystalline or polycrystalline

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30
Q

What is the microstructure of dental porcelain?

A

glass w/ some crystalline residuals )noncrystalline or amorphous silcate glass)

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31
Q

What is the building block of dental procelain?

A

silicon tetroxide

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32
Q

how is dental procelain processed?

A

sintering or melt at high temperatures

33
Q

define sinter

A

make a powered material (coalesce) into a solid or porous mass by heating
withOUT liquefication

34
Q

What are some characteristics of polymer bonds?

A

Covalent bonds, high MW, and long molecules (composed of C,O,N,H)

35
Q

How do polymers derive their strength?

A

entanglement and cross-linking or long chains

36
Q

What are the 4 steps of directpolymerization

A

Light activation of initiator
Initiation of monomer
Propagation of free-radical
Termination of free-radical

37
Q

What is the result of activation of the initiator molecule using light?

A

generates free radical

38
Q

How is the monomer initiated?

A

The free radical reacts with the monomer, opening a double bond through electron transfer to free radical, producing a radical monomer

39
Q

How is polymerization terminated?

A

There are no longer sites for the radical to react or run out of monomer

40
Q

Does a polymer change phase during polymerization?

A

Yes, the monomer is in a liquid state while a polymer is generally solid

41
Q

Define activation

A

free radical initiation via a specific wave length of light

42
Q

Define initiation

A

free radical combines with monomer, opening double bond

43
Q

One word definition of propagation

A

Growth

44
Q

Effects of propagation

A

chain growth
decreased V
shrinkage

45
Q

What is the structural difference between monomethacrylates and dimethacrylates

A

mono- forms linear chains that are dntangled

di- double amount of double bonds available allow for a branched and cross-linked chain

46
Q

Does branching and cross-linking increase or decrease mechanical properties and longevity?

A

increases

47
Q

What is the speed of polymerization once initiated?

A

Fast

48
Q

Does polymerization generate heat?

A

Yes

49
Q

What does “in vivo” mean?

A

direct placement into oral cavity

50
Q

Why can polymers be used in vivo?

A 
low viscosity 
stable
specific trigger for initiation
rapid setting
initation can occur at room temperature
51
Q

Are metal and ceramic able to be used in vivo?

A

No, they are used indirectly because of high processing temperatures
EXCEPT : amalgam and cements

52
Q

How are polymers used in dentistry?

A

temporary crowns, adhesives, restoratives, and impression materials

53
Q

what are the goals of composite resins?

A

to achieve some intermediate properties between the two material types (mixture of HA and collagen)

54
Q

Define rule of mixture

A

by knowing the phase in the structure of any material and its interfacial interactions, it is possible to predict the overall properties

**know the ratio

55
Q

What are the materials in dental composite resins?

A 
dispersed phase (glass filler for hardness)
matrix phase (monomer resin)
photoinitiatior (acitvate polymerization)
56
Q

what is the purpose on silane coupling agents?

A

to bond resin and fillers to each chemical to improve mechanical properties

57
Q

How does increasing filler VOLUME affect the property of composite?

A 
increase strength,
increase modulus (stiffness), increase viscosity, decrease shrinkage
58
Q

How does increasing filler SIZE affect the property of composite?

A

increases surface roughness

59
Q

What is the average filler amount? why?

A

75-80 wt % to produce high strength and stiffness

60
Q

Give the material structures

A

atomic arrangement
bonding
composition
defects

61
Q

What are examples of atomic arrangement?

A

crystalline (grains) vs non-crystalline (glassy)

62
Q

What types of bonding are there?

A

primary - metallic, ionic, covalent

secondary - van der waals, hydroen

63
Q

What are the 2 aspects of composition?

A

elements and phases

64
Q

What are two types of defects?

A

macroscopic (pores) and atomic scale (microflaws)

65
Q

What are two mass properties?

A

density and specific gravity

66
Q

define density

A

weight/unit volume

67
Q

Which materials have the highest and lowest densities?

A 
High = metal
Low = polymers
68
Q

Define specific gravity

A

relative density or the density of a material/ density of water

69
Q

Define thermal expansion

A

a thermal property where most things contract when cold and expand when hot

70
Q

Define heat flow

A

a thermal property, measuring the conduction of heat

71
Q

Do insulators have high or low eat flow

A

Low

72
Q

Do metals have high or low conductivity

A

High

73
Q

Do composites have high or low thermal conductivity?

A

Low

74
Q

What does it mean if a metal has high electrical properties?

A

it conducts electricity

75
Q

What is the significance of electrical properties?

A

corrosion of metal and galvanic reaction

76
Q

Do composite or ceramics conduct electricity?

A

No

77
Q

Define optical properties

A

its color, translucency, gloss, and surface

determines how light rays interact w/ surface

78
Q

How many dimensions do colors have?

A

3
hue (color)
value (intensity)
chroma (pureness)

79
Q

What is metamerism

A

two objects of the same color are perceived as different because of different reactions with different light sources

Dental Materials (6 decks)

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