Download - Material Properties restorative
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Material Properties
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Material Properties
Physical Properties
Mechanical Properties
Chemical Properties Biologic Properties
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Physical Properties
Thermal Properties
Temperature = Expansion
Temperature = Contraction
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Physical Properties
Thermal Properties Coefficient of Thermal Expansion- rate of change in
relation to temperature
Linear Coefficient of Thermal Expansion- if it is referring to
a single dimension
Average LCTE
Ceramics 1 to 15 ppm/ C
Metals 10 to 30 ppm/ C
Polymers 30 to 300 ppm/ C
Tooth Structure 9 to 11 ppm/ C
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Physical Properties
Thermal Properties
Percolation- cyclic ingress and egress of fluids at the
restoration margin
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Physical Properties
Heat Flow
Insulators- materials that does not permits an
electric current to flow
Conductors- materials that permits an electric
current to flow
Thermal Conductivity- rate of heat conduction
Thermal diffusivity- amount of heat conductionper unit time
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Physical Properties
Heat Flow
Dental pulp can withstand
37-42 C for 30-60 sec without any
permanent damage
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Physical Properties
Electrical Conductivity
Is a measure of relative rate of electron transport
through metal
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Physical Properties
Mass
Involves density and specific gravity
Density = materials weight / mass per unit volume
Metal- 6 to 9g/ cm3
Ceramic- 2 to 6 g/cm3
Polymer- 0.8 to 1.2 g/cm3
Specific Gravity density of material / density of water
1g/cm3
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Physical Properties
Optical Properties
Interactions with electromagnetic radiation
Propagation of light:
1) Reflection :
light is reflected in all directions, this is called diffuse
reflection
light in one direction only, this is called specularreflection
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Propagation of light:
2) Refraction : is a change in the direction of light as it enters the other
medium
3) Scattering :
this occurs when light passing through an opticalmedium redirects some of the radiation into directionother than that of the beam.
4) transmission:
light passing through an optical medium withoutattenuation is said to be completely transmitted. Totaltransmission is undergone by perfectly transparentmaterial
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Transparency, Translucency, Opacity
and Metamerism
Transparency: is the property of materials that
allow the passage of light in such a manner thatobjects can be clearly seen through them. e,.g.
glass and clear acrylic resin.
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Transparency, Translucency, Opacity
and Metamerism
Translucency: is the property of materials that
allow the passage of some light but disperses
( scatters or reflects) the rest so that objectscannot be clearly seen through them e.g. dental
porcelain, composite resin and pigmented
acrylic resin .
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Transparency, Translucency, Opacity
and Metamerism
Opacity: is the property of materials that
prevents the passage of light. An opaque
material either absorbs or reflects all of the
light. When all light is absorbed the materialappears black.
Examples of opaque materials are metals.
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Transparency, Translucency, Opacity
and Metamerism
Metamerism : the color of objects under one
type of light may appear different under
another light source.
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Physical Properties
Color parameters:a) Hue: this represents the color of the material .
E.g. blue, green, yellow , orange,
b) Chroma: it is strength of color, or it is a measurementof color intensity. A beaker of water containing one dropof colorant is lower in chroma than a beaker of watercontaining ten drops of the same colorant.
c)Value : it represents the lightness or darkness of a
color. A black standard is assigned a value of 0, where as awhite standard is assigned 100. A tooth of low valueappears gray and non-vital therefore it is the mostimportant parameter.
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Physical Properties
Munsells
Chart
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Physical Properties
Surface properties
interaction with other materials
How the surface interacts with saliva, cells and other
materials
Clinical consequence:
Bonding and adhesives
Wetting can be anticipated on the basis of the
Hydrophobicity (water-hating) and hydrophilicity (water
loving) of materials
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Physical Properties
Measure: contact angle used to measure how liquid interacts
with solid
Good wettinglow contact angle (approach 0)
Poor wetting- high contact angle (approach 180)
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Mechanical Properties
interaction of materials with loading
EXTERNAL LOAD
Compression
Tension
Shear
TorsionFlexion
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Mechanical Properties
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Mechanical Properties
LOAD Deformation
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Stress and Strain
Stress = Load per unit of cross sectional area
= Load / Area
Stain = Deformation / unit length
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Plastic Deformation
Ductile (Tension)
Malleable (Compression)
Brittle
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Studying Stress-Strain Curves