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Dental Materials > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Authors of textbook

A

Sakaguchie and Powers

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2
Q

Phoenicians dentistry

A

400BC with gold and ivory

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3
Q

Mayan dentistry

A

800 AD

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4
Q

Pierre Fauchard

A

(France)

father of modern dentistry

1728-treatise on the teeth described ivory denture construction

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5
Q

Philip Pfaff

A

Germany

waster impressions poured with plaster of paris

1756

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6
Q

Dubois de Chemant

A

France

A Dissertation on Artificial Teeth-1797

described the fabrication of porcelain teeth

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7
Q

George Washington’s dentures

A

Different sets used: human, cow, horse teeth, ivory, lead-tin alloy, copper alloy and silver alloy

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8
Q

When did studies on dental amalgam begin?

A

mid 1800s

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9
Q

Who did full scale studies on dental amalgam and when?

A

G.V. Black

1895

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10
Q

Ralph W. Phillips

A

department of dental materials at IU

Chair: 1940-1988

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11
Q

What is a biomaterial?

A

a nonviable material used in a medical device, intended to interact with biological systems

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12
Q

List of restorative dental materials

A
  • noble and base metals
  • amalgam alloys
  • cements
  • resin composites
  • glass ionomers
  • ceramics
  • gypsum materials
  • casting investments
  • dental waxes
  • impression materials
  • denture base resins
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13
Q

Challenge of dental biomaterials

A
  • warm
  • saliva
  • pH fluctuation
  • temperature fluctuations
  • high forces
    • stresses as high as 200MPa on cusp tips
  • esthetic demands
  • biological factors
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14
Q

Current vs. future solutions

A
  • future
    • initiate tissue repair or regeneration of missing/damaged tissues
  • current
    • biocompatible
    • interact permanently with oral tissues
    • match appearance of tooth structure and other visible tissues
    • exhibit properties similar to those of enamel, dentin, and other tissues
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15
Q

Organizations interested in standards

A
  • ADA
  • ANSI
  • ASC MD156
  • ASTM
  • FDA
  • FDI
  • ISO
  • ISO TC106
    • specific group for dentistry
  • NDA
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16
Q

The fxn of a standard is to

A
  • establish minimum values for properties which can be measured in lab tests which help ensure safety and efficacy of a dental material
  • provide for quality control
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17
Q

Do standards come before clinical intro?

A

No

Development of standards for a new type of dental material follow clinical introduction and use-usually by years

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18
Q

Do standards determine the best quality?

A

No

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19
Q

ANSI

A

American National Standards Institute (ANSI)

Clearinghouse for national standards

Conduit for USA standard representation with the International Standards Organization

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20
Q
  • World dental federation (FDI)
    • International standards organization (ISO)

How many dental standards?

How many countries?

What is the american member?

A

188 dental standards

31 countries

ANSI

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21
Q

FDA medical device amendment

A

1976

Any instrument, apparatus, implement, machine, contrivance, implant, or in vitro reagent used in the diagnosis, cure, mitigation, treatment, or prevention of disease in man and which does not achieve any of its principal intended purposes through chemical action within or on the body of man or other animals and which is not dependent upon being metabolized for the achievement of any of its principal intended purposes

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22
Q

FDA Classifications

A
  • Class 1=General Controls (low risk)
    • Regulation revolves around manufacturing
  • Class 2= General Controls and Special Controls (medium risk)
    • Product must meet performance standards
  • Class 3= General Controls and Premarket approval required (high risk)
    • Must pass tests for safety and effectiveness
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23
Q

Density of tubules in dentin

A
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24
Q

What is found in enamel?

Enamels composition by weight and volume?

A
  • Ameloblasts
    • Start at the DEJ and proceed outward to the tooth surface to form the enamel
  • Amelogenins and enamelins
    • Proteins that make up most of the enamel organic matrix
    • They are resorbed during tooth maturation to leave a calcified tissue that is largely composed of mineral and sparse organic matrix
  • Enamel Prisms
    • ~5 microns across
    • 1000s nanometers long
    • Have a very high aspect ratio: very long relative to cross section
  • 96% mineral by weight : 85% by volume
  • 1% lipid and protein : 3% by volume
  • Water : 12% by volume
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25
Q

Phosphoric acid on enamel

A

Commonly used in enamel bonding

Eliminates smear layers associated with cavity preparation

Dissolves persisting layers of prismless enamel in deciduous teeth

Differentially dissolves enamel crystals in each prism

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26
Q

Dentin components and its composition?

A
  • Odontoblasts
  • 50 vol% mineral (less mineral than enamel)
    • Carbonate-rich, calcium deficient apatite
  • 30 vol% organic
    • Type I collagen
  • 20 vol% fluid
    • Similar to plasma
    • Largely found in tubules that connect to pulp
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27
Q

Density of outer, middle, and inner dentin

A

outer is less dense, then middle, then inner

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28
Q

Transparent dentin

A

Tubules filled with mineral deposits

In front of a progressing caries lesion due to loss of overlying dentin

Tubules filled with minerals are much more difficult to etch with acid

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29
Q

Does enamel or dentin have a higher density?

Does enamel or dentin have a higher modulus of elasticity?

A

Enamel is more dense

Enamel has higher modulus of elasticity–> more rigid

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30
Q

Where do enamel cracks stop?

A

DEJ

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31
Q

What are biofilms

A
  • Polymicrobial communities
    • Complex
    • Surface-adherent
    • Spatially organized
  • Bacteria surrounded by polysaccharide matrix
  • Dental plaque
    • Oral biofilm on teeth and biomaterials
    • Dental plaque that is pathogenic causes disease
    • We will always have a biofilm and not all biofilms cause disease
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32
Q

what is oral biofilm in restorative materials influenced by?

A

Hydrophobicity-hydrophilicity

Surface free energy

Surface charge

Surface roughness

Pellicle formation

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33
Q

How is the oral biofilm in restorative materials studied?

A

In vivo, in situ, and in vitro

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34
Q

Force units of measurement

A
  • Pounds: the weight of an object
  • Weight=mass x acceleration due to gravity
    • Units of mass
      • slug (English)
      • kilogram-kg or gram-g (metric/SI)
    • Units of force
      • Pound-force (English)
      • dyne-d or Newton - N (metric/SI)
    • kilogram force-kgf
  • Metric prefixes
    • kilo - k - 1000 - 10 3
    • mega - M - 1,000,000 - 10 6
    • giga - G-1,000,000,000-10 9
    • centi - c - 0.01 - 10 -2
    • milli - m - 0.001 - 10 -3
    • micro - µ - 0.000001 - 10 -6
    • nano- n-0.000000001–10-9
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35
Q

Occlusal forces of molars, premolars, and incisors

A
  • Molars
    • 400-800N
  • Premolars
    • 200-500N
  • Incisors
    • 100-300N

Lower in child and geriatric patients

Lower in patients with removable dental appliances-dentures

Mandible is a lever system→ the further you get from the hinge, the less force there is

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36
Q

Stress

A
  • If a force acts upon a body and that body does not move-it is constrained-there must be developed in the body an equal and opposite force of reaction→ stress
    • Stress and applied load are different
    • Stress is the reaction to the applied force
  • Stress= Reaction Force/Area=σ
  • Units
    • Pounds per square inch (psi)
    • Newtons per square meter (N/m2) or pascal (Pa)
    • MPa=1x106 Pa
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37
Q

Types of stress

A

Shear- 2 equal but oppositely directed forces separated by a distance act upon a body-place in shear-shear forces-shear stress

Torsion-twisting of a cylindrical shape around its axis-screws that retain implant superstructures to the implant embedded in bone

Torque=force x length of lever over which it acts (foot-pounds, inch-pounds, meter-newtons)

Bending-flexure of a beam shaped object-complex stress

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38
Q

Strain

A

Strain (ε) = (L-LO)/LO = ΔL/LO

LO= original length

No units

Type of strain is related to type of stress: compressive, tensile, shear, complex

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39
Q

Engineering stress and strain

A

Calculate engineering stress→ engineering= based on original area

σ=force/original area= F/aO

Calculate engineering strain

ε=ΔI/Io

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40
Q

Proportional limit

A

Highest stress where stress and strain proportional

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41
Q

Elastic limit

A

Highest stress where the behavior of the material is completely elastic

Up to this point, if the force is removed that material will return to its original

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42
Q

Yield strength

A
  • The stress at which a material deforms plastically and there is a defined amount of permanent strain
  • Difficult to accurately determine proportional limit or elastic limit
  • Practical definition- accept a small amount of plastic deformation
  • Commonly 0.1% or 0.2% plastic strain
    • Stress is determined at which this occurs
  • Define yield strength at the % offset strain chosen
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43
Q

Elastic modulus

A
  • =stress/strain at or below elastic limit
  • Units same as stress; GPa, PSI
  • =initial slope of stress-strain curve
  • Stiffness or rigidity
  • E=stress/strain=σ/ε=(P/A)/(Δl/lO)
    • Flexibility= 1/E
  • Maximum flexibility=strain at elastic limit
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44
Q

Strength

A
  • A property related to the ability of an object to withstand applied force without fracture or excessive change in shape
  • A prerequisite of any structural material
  • Within limits, larger–>stronger
    • Physical limitations
    • Large objects may fail due to their own weight
  • Geometric constraints
    • In restorative dentistry, the size and shape are determined by the natural dentition
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45
Q

UTS UCS

A

The highest possible stress that can be withstood by a material without failure

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46
Q

Fracture strength

A

The stress level at which the material finally breaks

Some materials actually fracture at a stress level below the UTS or UCS

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47
Q

Poisson’s ratio

A
  • For elastic deformation only→ always positive
  • Specimens in tension or compression will exhibit deformation at right angles to the principle strain
    • v=-εy/εz
    • εy= transverse strain
    • εz= longitudinal strain
    • 0.25 < v < 0.5 for most materials
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48
Q

Shear modulus

A
  • E=elastic modulus or Young’s modulus
    • In uniaxial tension or compression
  • G=the shear modulus
    • In shear
  • Assuming Poisson’s ratio= 0.3
    • G=E/2(1+v)=E/2(1+0.3)=0.38E
    • v= Poisson’s ratio
    • G ~ 40%
    • Note: elastic deformation is easier in shear!!!
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49
Q

Ductility

A

ability to be drawn into a wire under tensile stress

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50
Q

Ductile vs. brittle materials

A
  • Limitation on use of brittle materials
    • tensile strength much lower than compressive
    • brittle materials are not ductile
    • Enamel is brittle
  • Temperature dependence of ductility
    • Some metals, most plastics
    • At low temperatures ductile materials can become brittle
  • Importance of ductility
    • Workability, safety
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51
Q

Measuring ductility

A
  • % elongation
    • Put broken ends of specimen together and measure Lf
    • 100(Lf-Li)/Li
    • 100 x (length after fracture-initial length)/initial length
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52
Q

Examples of ductile and brittle materials

A
  • Ductile Materials
    • Most metals and alloys
      • Pure gold is the most ductile of all materials
  • Brittle materials
    • Ceramics, tooth enamel, cements, many resins, dental amalgam
      • Klc < 2.0 MN m-3/2
      • Klc is a measure of the resistance of a material to crack extension under predominantly linear-elastic conditions
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53
Q

Malleability

A

ability to deform under compression instead of tension

54
Q

Stress concentration fractures

A
  • Material will break where there are flaws or defects because the area that the load is being spread across goes down a little
  • Strength is the stress value where it breaks
  • Stress concentration fractures:
    • Surface finish (crack size)
    • Internal flaws
    • Geometric stress risers-design
    • Bonded interface between 2 materials with different elastic modulus values
    • Bonded interface with different thermal expansion coefficients
    • Load applied to small area- Hertzian point load
55
Q

Fracture toughness

A

most important property for brittle materials in tension- measure of stress required to make a crack grow

56
Q

Tensile testing of brittle materials

A
  • Usually compressive strength tests performed for convenience
    • May not be clinically relevant
    • Crushing strength of gypsum, dental cements
  • Uniaxial tensile test very difficult for brittle materials
    • Grips cause stress concentration and premature failure
  • One solution: the indirect tensile test, “diametral compression test for tension”
    • actually tested in compression
57
Q

Diametral tensile strength

A

Tensile strength= (2P)/(pi*D*t)

P=load at fracture, D=diameter, t=thickness

Note: a successful diametral test results in a fracture along the dotted line with 2 half cylinders resulting

58
Q

T/F: materials fail in tension before compression

A

T

59
Q

3 point bend

what is the critical dimension?

A

Material will fail if maximum tensile stress exceeds tensile strength

occlusal-gingival height of the connector–> enters the equation for the 3 point bending stress at d2

Max stress decreases with an increase in the connector height squared

60
Q

Tear strength

A

Resistance to tearing force (combination of tension and torsion)

Useful for describing elastomeric polymers

61
Q

Resilience

A

Energy need to deform the material to the proportional limit

Resillience = area under elastic part of stress strain curve

=½ * prop limit * strain at PL

= prop limit2/ (2E)

Units N/m2 = N*m/m3 = j/m3 energy volume

62
Q

Toughness

A

maximum energy required to fracture-elastic and plastic

No general formula

Units N/m2 = N*m/m3 = j/m3 energy volume

63
Q
A

stiff–> steep slope

ductile–> long plastic deformation

brittle–> short plastic deformation

strong–> takes high stress to deform plastically

resilient–> large area under elastic portion of curve

flexible–> less steep slope

64
Q

Dynamic modulus

A

For small cyclical deformations at a given frequency and particular point on the stress strain curve

65
Q

Impact strength

A
  • A very rapidly applied force
    • Very difficult to measure
    • Best described by energy transferred
  • Related to resilience and toughness
  • If no permanent deformation takes place:
    • Impact energy=kVR=(kVP2)/(2E)
    • R=resilience=P2/2E, V=volume, k=shape constant, P=proportional limit, E=elastic modulus
66
Q

Static fatigue

A
  • Failure of a brittle material after constant stress experienced over a long time
  • Usually, a result of environment and applied load leading to crack growth
    • Corrosion
    • Ceramics and water
    • Impact of surface finish
67
Q

Cyclic loads

A
  • Magnitude varied with time in a periodic manner
  • Can produce failure at stresses below UTS or even below proportional limit
  • dynamic fatigue
    • cyclic load causes crack growth
  • important clinically
    • implants
    • removable partial denture framework
  • endurance limit: where it won’t break no matter how many more cycles
68
Q

Dynamic fatigue

A
69
Q

Time dependent deformation of liquids, crystalling solids, and amorphous solids

A

Liquids-flow

Crystalline solids-creep

Amorphous solids-flow

70
Q

Rheology

A

study of flow of liquids under applied stress

71
Q

Liquids are usually considered…

A

incompressible and incapable of supporting a tensile stress

72
Q

Liquids flow in response to what kind of stress?

A

shear stress

73
Q

viscosity

A
  • the resistance a liquid exhibits to flow
  • viscous liquids
    • Tar, molasses, honey
    • Dental resin composites (in unpolymerized state)
  • low viscosities
    • water, alcohol, acetone
    • cavity varnish
  • usually decreases with increasing temp
  • may depend upon shear strain rate
  • may depend upon previous shear history-thixotropic
  • units: centipoise (cP=mPa*sec)
    • water at 20C ~1.0cP=1.0mP
74
Q

shear of a viscous liquid

A
75
Q

Viscosity of some dental materials after mixing

A
76
Q

Types of rheologic behavior

A
  • Newtonian→ linear
    • Zinc phosphate cement, water
  • Pseudoplastic
    • Glass ionomer, rubber impression material
    • Thixotropic
      • The change in viscosity of a material with time
      • Prophy pastes
  • Dilatant
    • Heavily filled resin composite, microfilled composite
  • Thermoplastic materials
    • Become plastic on heating and harden on cooling, and are able to repeat these processes
77
Q

creep

A
  • time dependent plastic deformation of a crystalline solid under a static stress (only at temperatures that approach melting point)
  • Thermally activated; only significant at temperatures > 0.8 Tmp oK
  • T> 0.95Tmp at ceramic firing temperature
    • Sag-distortion of cast metal substructure
  • 37oC is > 0.9Tmp for Sn-Hg component
  • ADA specification #1
  • Creep <3% over 3 hours at 36 MPa
78
Q

Flow

A
  • Time dependent deformation of noncrystalline solids under static pressure
  • Flow rates are very dependent on T
  • Resins, waxes
  • Thermoplastic polymers
  • non crystalline solids (supercoiled liquids with no melting point)
79
Q

most noncrystalline solids show

A

viscoelastic behavior

80
Q

Viscoelastic diagram

A
81
Q

stress relaxation

A
  • reduction in stress in a material subjected to a constant strain, wheras creep is the increase in strain in a material under constant stress
    • Temperature dependent
    • Dental waxes
    • Heavily deformed crystalline materials
    • Orhto wire
82
Q

Strain rate sensitivity

A

sensitive to how rapidly it is strained

Impression materials

83
Q

Hardness

A
  • Resistance to indentation
  • Fast and easy to measure
  • Indirectly related to other properties
    • Strength, proportional limit, ductility
    • Good for quality control or comparing very similar materials
  • Microhardness versus macrohardness
84
Q

Macro hardness tests

A
  • both good for ductile material: beforms permanently without breaking
  • Brinell
    • Spherical indenter
    • BHN=load/projected area (BHN=Brinell hardness #)
    • Not good for brittle or elastic materials
  • rockwell
    • Can also be micro

Spherical or conical indenter

Depth of penetration measured

Not good for brittle or elastic materials

85
Q

micro tests for hardness

A
  • Vickers
    • 136o diamond pyramid indenter
    • VHN load divided by projected area calculated from lengths of diagonals
    • Good for materials except highly elastic ones
    • Used for tooth structure
  • Knoop
    • Asymmetric diamond pyramid
    • Good for all materials including elastic
    • Long diagonal used to calculate area
    • Used for tooth structure
86
Q

Barcol

A

spring loaded indenter, measures depth of penetration:

Depth of cure of restorative resins

Softer materials

87
Q

Shore A

A

spring loaded indenter, measures depth of penetration:

Rubbery materials such as impression materials, denture liners and maxillofacial prosthesis elastomeric materials

88
Q

Moh’s hardness

A

The ability of one material to be plastically deformed by scratching with another material

Correlate- diamond burs used to scratch away tooth structure

Used since 1820

Scale of 1-10

Talc=1 (soft)

Diamond=10 (hard)

89
Q

Adsorption

A
  • A liquid or gas firmly adhering to the surface of a solid or liquid
    • Related to surface free energy
    • Two identical materials in contact-cohesion-direct gold
    • Two different materials in contact-adhesion
      • Adherend
      • Adhesive
90
Q

Absorption

A

diffusion process into a liquid

91
Q

sorption

A

adsorption and absorption

92
Q

Surface properties of solids

A
  • Surface energy-interface between different phases-solid, liquid, gas
  • Cohesive force (bonds) unbalanced at surface of solids
  • Adhesive forces can develop
    • Primary-chemical reaction-gases like oxygen on metal surface-chemisorption
    • Secondary-physical forces-inert gases on metal surface-physisorption
    • Soap spreads out more and lowers surface tension
    • The cohesion between water and surface -active agent is less than that between water and water
93
Q

Wetting a solid-liquid interface

A
  • Required for maximum adhesion
  • Related to interfacial energies
    • Contact angle
  • Balance of forces at interface
94
Q

Wetability penetration coefficient

A
95
Q

Thermal properties

A

Dimensional change→ change in temperature affects dimension

Linear coefficient of thermal expansion

𝝰=𝝙I/(IO * 𝝙T) (units 1/oC)

Relationship: aV=2𝝰

If thermally induced stress→ margin opening→ unacceptable

96
Q

Thermal conductivity

A
  • Rate of steady state heat conduction through unit area of material with unit thickness with 1oK temperature difference-units: watts/(m*K)
  • Lower thermal conductivity
    • Insulator- tooth structure
  • High thermal conductivity
    • Conductor-most metals
      • Sensitivity, pain, pulp damage
  • Thermal diffusivity
    • How fast temperature changes-most common dental problem
  • Non steady state
    • Eating, drinking hot or cold substances (0oC-65oC)
  • 5.5oC increase in temperature can cause pulp damage
97
Q

Diffusivity equation

A

h=thermal diffusivity cm2/sec

k=thermal conductivity

cp=specific heat

ρ=density

h=k/(cpρ)

98
Q

Insulation ability of a layer of material is proportional to…

A
  • its thickness divided by the square root of diffusivity→ thickness is more important than h
    • Z=t/h1/2
      • Z=insulating ability
      • h=thermal diffusivity
      • t=thickness
  • Insulators protect pulp from temperature change
    • E.g. resins, cements
  • Insulators used for denture base-patient loses sensation of hot or cold food and drink
99
Q

Porcelain vs. teeth

A

Porcelain (more amorphous) vs. teeth (more crystalline)

100
Q

Visible light part of electromagnetic spectra

A

400-750nm (red is high, blue is low)

101
Q

Illumination is defined by

A

wavelength and intensity

102
Q

UV light on spectrum

(UVA, UVB, UVC)

A

200-400nm

UVA 315-400

UVB 280-315: sunburn, skin damage

UVC: ionizing, germicidal

103
Q

Reflection

A

Specular-mirrorlike-glare

Diffuse- scattered light-contains most of the color information for the object

Reflectance spectrum

104
Q

Normal color vision

A

red, green, blue cones

105
Q

color blindness

A

most affect red and green

1/12 men, 1/200 women

106
Q

Conditions influencing color vision

A

Light levels-color vision requires threshold value for illumination- B&W vision more sensitive

Surroundings

Fatigue- after image (the longer you stare at something, the more the color shifts)

Size of object

Viewing angle

107
Q
A
108
Q

3 dimensions of color

A
  • Hue- primary wavelengths
    • Red, green, blue, etc.
  • Value-lightness→ we are most sensitive to
    • Black and white
  • Chroma-saturation
109
Q

color matching chart

A
110
Q

Metamorism

A

looks different under different lights

An object can only reflect wavelengths present in the incident light

An object may appear very different if viewed under illumination with different spectra

2 objects with different reflectance spectra may appear similar or different depending upon the illumination-metamerism

111
Q

What must always be given when providing L*a*b values?

A

type of illuminant used

112
Q

Fluorescence

A

Absorption of short wavelength light and re-emission of longer wavelengths

113
Q

Enamel and dentin strongly absorb and reflect…

A

Enamel and dentin strongly absorb 360-380nm UV and emit 450nm blue light (just below visible range)

  • “Vital” appearance under illumination with a significant UV component-including sunlight
  • Some artificial light, photoflash lamps, “black light”
114
Q

Illuminant for color matching

A
  • Color rendering index (CRI)
    • Illuminant compared to “an ideal” illuminate
    • Historically, sunlight has been used
    • Artificial illuminant as designated by CIE
  • Perfect match: CRI=100 (try to get >90)
  • Full spectrum illumination- color rendering index CRI>90, color temp>5500oK
  • Natural daylight
  • 2 light sources with different spectral content
  • Color matching in clinic→ shade guides are used to communicate color to lab
115
Q

full spectrum illumination

A

color rendering index CRI>90, color temp>5500oK

116
Q

Why is biocompatibility relevant to dentist?

A
  • Safety of patient
    • Hypersensitivity and allergy issues
    • Benefits of use must outweigh the risks
  • Safety of the staff
    • Chronic exposure (e.g. amalgams, latex, resin-based materials HEMA TEGDMA, camphoroquinone)
  • Legal liability
  • Regulatory compliance (e.g. elimination of mercury from dental waste)
117
Q

Biocompatibility definition

A

ability of a material to elicit an appropriate response in a given application in the body

118
Q

3 key concepts of biomaterials

A

Biomaterials are not biologically inert

Biocompatibility is a dynamic process

Biocompatibility is a property of a material and its environment

119
Q

Critical adverse effect and critical concentration

A

Critical adverse effect: lowest exposure level with event

Critical concentration: critical amount that causes effect

120
Q

allergic reaction

A

Patch test

Remember: toxicity=dose dependent, allergy=dose independent

121
Q

Metals degrade by

A

by wear, dissolution or corrosion

Dissolution vs. corrosion (difference between chemical concentration gradients and electrical current gradients)

122
Q

ceramics and composites breakdown from

A

cyclic stresses

123
Q

biological response to corrosion depends on

A

materials’ composition, amount of ion/molecule, etc.

124
Q

Surface characteristics

A
  • Different composition from the bulk (metal and resin composites)
    • Titanium alloys (TiO2 layer)
  • Roughness increases the release allergens, mutagens, toxins
  • Rough surface
    • Promotes corrosion
    • Increase the release of ions may lead to adverse effects
  • Acidic beverages= degradation of ceramics, increase roughness
  • Unfinished surfaces
125
Q

Biocompatibility depends on

A

Chemical nature of components

Physical nature of components

types/locations of patient tissues exposed to the device

Surface characteristics of the material

Amount and nature of substances eluted from material

126
Q

osseointegration

A

Process of forming a direct structural and functional interface between live bone and an artificial implant surface without any intervening fibrous connective tissue

127
Q

Dental ceramics properties

A

(acid sensitive)

Excellent chemical durability

Acidic beverages and/or auxiliary dental products (acidulated phosphate fluoride, APF)

Important issue: bonding protocol

toxicity of HF–> burns, dangerous protocol

Dilute solutions deeply penetrate before dissociation, thus causing delayed injury and symptoms

128
Q

Classes of tests

A

Initial test- in vitro, using cells

Secondary test-in vivo test, using animals

Usage test-tested in situation identical to its intended clinical use

129
Q

Early and contemporary strategies for the use of biocompatibility tests to assess the safety of materials

A
130
Q

Future strategies for biocompatibility testing

A
131
Q

What do the colors represent?

A

red=proportional and elastic limit

blue=max flexibility

green=resistance

purple=toughness

yellow=yield strength

pink=tensile strength

Dental Materials (1 decks)

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