Physical Properties Flashcards
General Classes of Biomaterials
_____
____
_____
____
}Metal and Alloys
}Polymers
}Ceramics
Composites
}Metal and Alloys
______
_____
_____
}Dental amalgam
}Gold alloys
}Titanium
}Polymers
____: used for
_____: used for
}Poly (methyl methacrylate) (PMMA)
}Polyvinyl siloxane (PVS)
PMMA is what we use for denture base material
PVS is used for impression material
}Ceramics
____
____
Used for
}Dental porcelain
}zirconia
Tooth color restorative material
}Composites
______
what is it
Used for
}Dental resin composite
Composite is combo of any of the above
Restorative material
What is composition of enamel?
Enamel: roughly ____% of _____ materials
Which category would we put enamel in? ___
Dentin–>_____
There is ___ inside
Pulp is Composed of ____ &____
We have to ______________ when we think about restorative material
Enamel: roughly 95-98% of inorganic materials
Which category would we put enamel in? Ceramic
Dentin–>composite
There is pulp inside
Pulp is Composed of blood vessels, nerves
We have to protect the pulp when we think about restorative material
Overview of the Lecture
- T
- t
- t
- E
- g
- e
- W
- R
- v
- v
- S
- }Thermal properties
- }thermal conductivity
- }thermal contraction and expansion
- }Electrical properties
- }galvanism
- }electrochemical corrosion
- }Wear
- }Rheological properties
- }viscosity
- }viscoelasticity
- }Solubility and sorption
Thermal conductivity
The thermal conductivity, ___, of a substance is the ____ ___ ____in ____, or ___ per ___ passing through a body ____ thick with a cross-section of ____ when the temperature ____ is __.
Thermal ____ and ____
Heat can transfer from ___ to ___ whenever there is a ______________ thru this material
Depending on _______________ inside the material, the material is categorized as either a _____ or ____
Diff types of material transfer heat in diff ways
}The thermal conductivity, K, of a substance is the quantity of heat in calories, or joules, per second passing through a body 1 cm thick with a cross-section of 1 cm2 when the temperature difference is 1°C.
}Thermal conductors
}Thermal insulators
Heat can transfer from one side to another side whenever there is a heat difference thru this material
Depending on how fast heat transfers inside the material, the material is categorized as either a conductor or insulator
Diff types of material transfer heat in diff ways
Thermal conductivity: Energy Transfer
Metal and Alloys - By
Polymers - By
Ceramics -By
Metal
Polymers and Ceramics
}Metal and Alloys - By vibration of atoms and motion of electrons
}Polymers - By vibration/rotation of chain molecules
}Ceramics -By vibration of atoms
The different categories, The way they transfer E differs
Metal transfers heat pretty quick
Polymers and Ceramics transfer heat very slow
Thermal conductivity of different things
Metals have ___ thermal conductivity than ____ including ___ and ___
We can see our tooth structure Is in the category of thermal ____
This is to
When we use any material to match our natural tooth structure we need to keep this in mind
High to low:
Metals have higher thermal conductivity than non metals including polymers and ceramics
We can see our tooth structure Is in the category of thermal insulator
This is to Protect the pulp from a sudden T change inside our mouth
When we use any material to match our natural tooth structure we need to keep this in mind
High to low:
Metals (dental amalgam)> nonmetals (resin composite>porcelain>enamel>dentin)
Clinical implications of Thermal conductivity
____
____
}Restorative materials
}Denture base materials
Restorative:
For example, this is our tooth structure,
If we have decay/cavity in there, what we do? We ______
If we fill it in with a metal….
If cavity is deep, its
What do we need to do before we add metal? ________
____________
If tooth is dead,__________
If the tooth is still alive we have to consider this
If we don’t take this step, tooth will have ______ and overtime the ____ ___ ___ from _____.
For example, this is our tooth structure,
If we have decay/cavity in there, what we do we mechanically drill off those areas and we fill it in with restorative materials
If we fill it in with a metal….
If cavity is deep, its close to pulp
What do we need to do before we add metal? We need to protect the pulp
We Put layer of thermal insulator underneath it! If tooth is dead, that’s another story we have nothing to protect.
If the tooth is still alive we have to consider this
If not, tooth will have sensitivity and overtime nerve will die from heat
Dentures:
Dentures:
___ vs. ____
This polymer is a thermal ____
The Metal is ______
When patients use those materials
Metal can transfer heat_____then the one on the left
Patients will be able to_____
So which do patients prefer?
Most patients prefer ____ bc
The polymer: _____________
Polymer covers the _____
One on right is metal
This polymer is a thermal insulator
The Metal is conductor
When patients use those materials
Metal can transfer heat faster then the one on the left
Patients will be able to feel Temp of their food
So which do patients prefer?
Most patients prefer metal, you can feel more
The polymerà I cannot taste my food
Polymer covers the mucosa
Heat generation during cavity preparation
When we drill tooth we use high speed hand piece which ______________
This is experiment where they put thermal ___ in ____ to measure heat generated
If no coolant __________________
This will _____ the pulp even though _______
The ____ you put out with hand piece affects the heat generated too! (high ___, ____ heat)
When you use light force (low P), you have coolant and T doesn’t increase too much
Protects tooth structure as well
When we drill tooth we use high speed hand piece which generates a lot of heat
This is experiment where they put thermal ___ in ____ to measure heat generated
If no coolant, it can heat up very fast and to very high T
This will damage the pulp even though dentin is thermal insulator
The P you put out with hand piece affects the heat generated too! (high P, high heat)
When you use light force (low P), you have coolant and T doesn’t increase too much
Protects tooth structure as well
Thermal contraction and expansion
The ____ in ____ per ___ ____ of a material for a ___ change in temperature is called the linear coefficient of thermal expansion (CTE, α, × 10−6/° C ).
Equation
Thermal contraction and expansion
}The change in length per unit length of a material for a 1°C change in temperature is called the linear coefficient of thermal expansion (CTE, α, × 10−6/° C ).
Equation
Contraction and Expansion
When we drink anything cold–> things _____
Hot material will _____
This is how we calculate how much the material dimenstion will change when T changes
Pay attention to alpha.
We use linear coeff of thermal expansion bc _____
This represents how the material will respond when _____
This is similar to the ______
Modulus (elasticity) is an important parameter …Tells you how material will respond to ____
Linear coeff of thermal exp Shows you how material will respond to ____
When we drink anything coldà things shrink
Hotà material will expand
This is how we calculate how much the material dimenstion will change when T changes
Pay attention to alpha.
We use linear coeff of thermal expansion bc its usually hard for us to measure the Volume
This represents how the material will respond when T changes
This is similar to the Strain Stress curve
Modulus (elasticity) is an important parameter …Tells you have material will respond to stress
Linear coeff of thermal exp
Shows you how material will respond to T change
Linear Coefficient of thermal expansion
alpha
Impression materials are polymers…__________
Amalgam are metal..________
As a restorative what do you want to have?
You want it to be ___________
alpha
Impression materials are polymers…They have pretty high alpha
Amalgam are metal…Their alpha is about 10X less then polymers
As a restorative what do you want to have
You want it to be similar to tooth structure
waxes> impression>sealants> composites> amalgam> porcelain> tooth
Coefficient of Thermal Expansion (´10-6/°C)
Enamel
Amalgam
Composite
Gold
Ceramic
Enamel 11.4
Amalgam 22-28
Composite 30-40
Gold 13.8
Ceramic 7-8
Direct Restorative Material (2 left)
____ and _____
We do what with these?
This will change _____ than enamel when the T changes bc they have a ____ coefficient.
Amalgam (top) and composite (bott)
We directly place these in patient mouth….directly chairside
These will change more (than enamel) when the T changes
Because they have Higher coefficient
Indirect restorations
____ and ____ are indirect restoration
We do what?
Time
Money
Have ____ change to enamel
More ___ ____ to enamel
Indirect restorations have ________ match to enamel than direct
The gold and ceramics are indirect restoration
We send that to lab. When it comes back we bond it.
Indirect
We send to lab
Takes longer
More expensive
Have similar change to enamel
More similar alpha to enamel
Indirect restorations have better match to tooth then direct
If same T change, the higher coefficient,
With same L initial and same T change, increase alpha
This also means that if the material has higher alpha, this material will have more change in dimension if
When filling is big, T change a little, ________!
This creates a ________, stress to existing tooth structure.
We recommend using _____ here
This will help tooth survival rate in the long term
the higher this material will expand or shrink
increase change in dimension
this restoration is bigger.
Bigger restoration will create bigger dimensional change when the T changes
When filling is big, T change a little, Dimension will change a lot!
This creates a stress in the interface, stress to existing tooth structure.
We recommend using indirect here
This will help tooth survival rate in the long term
Clinical implications of Contraction and Expansion
__________: ___ ___, ______
_____________
Affects restoration - tooth gap, microleakage
}Have matched CTE for materials used together
}Affects restoration - tooth gap, microleakage
may cause _____
residual _____
post op _____
When the T change in our mouths, the tooth will ______
We want our restoration to _________________
We want to avoid getting a _______
If we have too much stress in the interface, it can cause _______ if the material is bonded in
If it stays bonded it will create a _________ This stress can cause tooth to react sensitive
This is why we get post op sensitivity…too much _______
If its debonded, the _________, so can any ______
This can cause sensitivty to the patient
Can cause _____ or ______
}may cause debonding
}residual stress in bonded restoration
¨post op sensitivity
When the T change in our mouths, the tooth will change dimension
We want our restoration to shrink or expand in same way as tooth
We want to avoid getting a stress in bw the interface
If we have too much stress in the interface, it can cause debonding if the material is bonded in
If it stays bonded it will create a stress to the tooth structure. This stress can cause tooth to react sensitive
This is why we get post op sensitivity…too much stress on tooth structure
If its debonded, the bacteria can get in, so can any liquid when you chew
This can cause sensitivty to the patient
Can cause sensitivity or secondary decay
}Have matched CTE for materials used together
__________
__________
When you use diff types of materials together in clinic, in dentistry, when they go thru a T change, the alpha value has to _____
One such is example PFM
PFM: ____ inside ____ outside
Combines ____ of metal and____ of ceramic
We increase the T in the oven so ceramic and metal can fuse together
During cooling process, T will change from _______
During that process if the alpha for both materials doesn’t match there will be too much _____ and the porcelain can _____
Its critical that these materials have same coefficient
Gold casting:
Gold also goes from high T to low T
Gold will ______
In order to compensate for the shrinking, we need to have __________
This other material has to match the _________.
}Porcelain fused to metal (PFM) crowns
}Gold casting
When you use diff types of materials together in clinic, in dentistry, when they go thru a T change, the alpha value has to match
One such is example PFM
PFM: metal inside and porcelain outside
Combines strength of metal and esthetics of ceramic
We increase the T in the oven so ceramic can fuse together
During cooling process, T will change from High T to low T
During that process if the alpha for both materials doesn’t match there will be too much stress on porcelain and porcelain can fracture
Its critical that these materials have same coefficient
Gold casting:
Gold also goes from high Tà low T
Gold will Shrink
In order to compensate for the shrinking, we need to have another material expand a little bit when its in high T
This other material has to match the expansion coeff of gold
