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Operative > Biomaterials > Flashcards

Biomaterials Flashcards

1
Q

Any substance, other than a drug, that can be used to treat,
augment, or replace any tissue, organ, or function of the body
is a biomaterial

A

Biomaterial

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2
Q

4 Major Classes of Dental Materials

A
  • Metals and Alloys
  • Porcelains and Ceramics
  • Polymers
  • Composites
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3
Q

Reclassified_______ from class I to class II

A

amalgam

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4
Q

Types of interatomic bonds:

Primary

A

Ionic, covalent, metallic

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5
Q

Types of interatomic bonds:

secondary

A

Hydrogen bonds, Van der Waals forces

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6
Q
  • Electrostatic attraction of positive and negative charges
  • Involves electron transfer between ions
  • Properties:
  • non-directional, strong bonds
    • 100-200kcal/mole
  • No free electrons, good thermal and electrical insulators

• Examples
- Ceramics, gypsum

A

Ionic

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7
Q

Valence electrons shared by 2 atoms

Properties
• Often directional bonds
• 50-100kcal/mole
• Low electrical and thermal conductivity
• Water insoluble

Examples:
Water, glass, polymers, composite

A

Covalent

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8
Q

Cluster of positive metal ions surrounded by a gas of electrons.

Properties
• Non-directional bonds
• 100 kcal/mole
• High electrical and thermal conductivity

Examples
• Amalgam and gold alloys

A

Metallic

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9
Q

Physical Properties
Depend on the type of _____ and
the bonding present in material

A

atoms

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10
Q

Quantity of heat passing through 1 cm thickness of material.

A

thermal conductivity

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11
Q

How quickly crown interior approaches temp of exterior

A

Thermal Diffusivity

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12
Q

Applied force referred to as _______.

A

load

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13
Q

When load (force) applied to material,_____ develops in response

A

STRESS

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14
Q

Strength of material= stress at______.

A

fracture

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15
Q

• Tensile • Compressive • Torsion • Shear • Flexure

A

Types of Force/Stress

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16
Q

Tensile Strength-_______ force

A

PULLING

lowest strength for most materials

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17
Q

Measure of the stress necessary to fracture a material by 2

opposing forces directed away from each other

A

Tensile Strength

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18
Q

Measure of the stress necessary to fracture a material by 2

opposing forces directed toward each other

A

Compressive Strength

Highest strength measure for most materials

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19
Q

Torsion Strength-______ force

A

TWISTING

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20
Q

Shear Strength-______ force

A

SLIDING

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21
Q

Stress necessary to rupture a material by 2 opposing

parallel forces directed toward each other but not in the same plane

A

Shear Strength

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22
Q

Flexural Strength-______ force

A

BENDING

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23
Q

Protrusive movement

A

Examples of DENTAL STRESS on the anterior teeth.

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24
Q

Posterior occlusion

A

Examples of DENTAL STRESS of chewing

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25
Q

tripodized occlusal contacts allow:

A

minimal stress by distributing occlusal load across maximum area.

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26
Q

Premature Contact results in

A

OCCLUSAL STRESS IS INCREASED

and Potential restoration failure

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27
Q

The DEFORMATION that occurs in a material when force is

applied to the material

A

strain

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28
Q

______ and_____ are interrelated

• If you have one, you will have the other

A

Stress

strain

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29
Q

The TEMPORARY distortion of a material by applied force.

When force is removed, materials reverts to original form.

A

elastic strain

30
Q

PERMANENT distortion of a material

A

PLASTIC Strain

31
Q

Deformation BELOW the elastic limit

A

Elasticity

32
Q

Plastic deformation (elongation) from tensile stress

A

Ductility

33
Q 
Plastic deformation (elongation) from COMPRESSIVE
stress
A

Malleability

34
Q

the quality of having minimal to no plastic deformation

A

Brittleness

35
Q

The quality of stiffness of a material

A

Modulus of Elasticity

36
Q

Energy absorbed to reach elastic limit

A

Resilience

37
Q

Energy absorbed to cause fracture

A

Toughness

38
Q

Mechanical properties of Ceramics

A

Strong, brittle, stiff

39
Q

Mechanical properties of metal/alloy

A

Strong, stiff, some elasticity, ductile

40
Q

Mechanical properties of dental composite

A

Weaker, brittle, lower elastic modulus

41
Q

Mechanical properties of Elastomeric polymer

A

Weaker, lower elastic modulus, ductile

42
Q

solid mixture of 2 or more metals

A

alloy

43
Q
  • Ag 40-74%
  • Sn 26-30%
  • Cu 2-30%
  • Zn 0-1%
A

Composition of alloy powder

44
Q

• High copper content

A

12-30%

45
Q

• Low copper content

A

2-6%

46
Q
  • More Hg needed to wet powder
  • More condensation pressure needed
  • ROUGHEST surface
A

Lathe cut of alloy

47
Q
  • Atomize liquid alloy into spheres
  • Less Hg needed to wet spheres
  • More plastic
  • Easier to achieve interproximal contact
  • SMOOTHEST surface
A

Spherical particles of alloy

48
Q
  • Combination of lathe and spherical
  • Better condensation properties
  • Hg 47-50%
  • Smoother than lathe
A

• Admixed

49
Q

What is used at the school of dentistry?

A

• Admixed

50
Q
  • Gamma phase: Strong, hard
  • Gamma 1 phase: Brittle intermediate strength
  • Gamma 2 phase: weak, prone to corrosion, increased creep
A

Amalgam phases

51
Q

With high copper content, what is increased and what is eliminated?

A

Increased strength and hardness

the gamma phase II is eliminated.

52
Q

• Too much= decreased strength • Problem ameliorated with pre-capsulated alloys

A

mercury content

53
Q

• Under OR over triturated= decreased strength

A

Trituration

54
Q
  • Express excess Hg to surface= INCREASE strength • Minimize porosite
  • Adapt amalgam to cavity walls: 45 degree angle to walls
  • Condensation pressure: lathe cut requires most pressure, spherical requires least
A

Condensation technique

55
Q
  • Greater time elapsed, lower strength

* Discard amalgam not condensed within 3-4 minutes

A

Elapsed time between trituration and condensation

56
Q

• Decrease density= decrease strength • Undertrituration • Improper or delayed condensation

A

Porosity

57
Q

• 20 minutes= 6% of 1 week compressive strength • 8 hours=70% of 1-week strength • Caution patients to avoid heavy occlusion for first 8 hours

A

Hardening rate of amalgam: time after condensation

58
Q

Time -temperature-strain relationship

A

CREEP

59
Q

_____ correlated to marginal breakdown

• “ditched” margins

A

Creep

60
Q

______ Cu amalgams= higher creep

• Conversely,_____ Cu amalgam= lower creep

A

Low

high

61
Q
  • Formation of a surface layer
  • Oxide, sulfide, or chloride flim
  • GAIN of material
A

Tarnish

62
Q
  • Deterioration of metal by reaction with the environment
  • Electrochemical process: metal dissolution (pitting)
  • LOSS of material
  • Gamma 2 phase is most susceptible
  • Thus, low Cu alloys have higher corrosion susceptibility
A

Corrosion

63
Q
  • Occurs between dissimilar metal restorations contacting each other
  • Example: gold crown occluding with amalgam restoration
  • Gold is cathode, amalgam is anode
  • Amalgam loses material
A

• Galvanic Corrosion

64
Q 
Electric potential between dissimilar metals
• Circuit closes when in occlusion 
• Results in pain 
• Resolves over time
• Tarnish develops
A

Galvanic Shock

65
Q

• Occurs are margins of amalgam restoration
ADVANTAGE:
• Corrosion seals margins-> decreased microleakage
• Occurs more quickly with low Cu alloys

A

crevice corrosion

66
Q

Average replacement age LOW Cu (no Zn):

A

5-10 years

67
Q

Average replacement age HIGH Cu (with Zn):

A

14-25 years

68
Q
  • Easy to place
  • Less technique sensitive
  • More durable
  • Resistant to fracture
  • Not abrasive to opposing teeth
A

Amalgam advantages

69
Q
  • Esthetics
  • Does not bond to tooth
  • Subject to corrosion and tarnish
  • Marginal breakdown and microleakage
A

Amalgam disadvantages

70
Q

T/F Amalgam is not free mercury

A

true

71
Q
  • Requires office to use amalgam separators • Prohibits flushing waste amalgam down the drain • Prohibits use of bleach or chlorine containing cleaners
  • May lead to dissolution of Hg from amalgam
A

• 2017 EPA ruling concerning dental practices

Operative (12 decks)

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