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
Electrical Properties: Galvanism
- It is the ____ of electrical ____ from a chemical reaction, typically between two chemicals with ____ ______.
- Electronegativity, symbol __, is a chemical property that describes the _______
- In dentistry, this results from a difference in____ between_____ metallic fillings in ____ or ____ teeth.
}It is the induction of electrical current from a chemical reaction, typically between two chemicals with differing electronegativities.
}Electronegativity, symbol χ, is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself.
}In dentistry, this results from a difference in potential between dissimilar metallic fillings in opposing or adjacent teeth.
Galvanism
Electrical properties: Mainly refers to ___
This is one we see a lot it clinic–> Galvanic effect
Galvanic effect:
When _____ of metal come in contact
If They Differ in e-neg and can create a current bw them
The precious metal are pretty ____
But Those metals like Zn are _____
When those metals touch they get a current bw them
Inside our mouth, ____ can be used as ____
When two metals touch it creates an ______and there will be an _____ going thru the tooth
If top is alive, patient will _____
Electrical properties: Mainly refers to metal
This is one we see a lot it clinicà Galvanic effect
Galvanic effect:
When 2 types of metal come in contact
If They Differ in e- and can create a current bw them
The precious metal are pretty inert, stable
But Those metals like Zn are very active
When those metals touch they get a current bw them
Inside our mouth, saliva can be used as electrolytes
When two metals touch it creates an electric cell and there will be an electric current going thru the tooth
If top is alive, patient will bfeel a shock.
Galvanism
- Dental metallic restorations, in conjunction with ___ or ____ such as ____, make up an ___ ___.
- When two opposing fillings contact each other, the cell is ____________.
- If the flow of current occurs _____ _____ ______, the patient experiences pain
- The more ____ restoration may ____.
- ____ can be used as electrolytes
- When metal touches, can create a current thru teeth
- Patient will feel a __
- The more ____ _____ will corrode
- This is one of the reasons why metal will corrode in our mouth
Dental metallic restorations, in conjunction with saliva or tissue fluids such as electrolytes, make up an electric cell
}When two opposing fillings contact each other, the cell is short-circuited
}If the flow of current occurs through the pulp, the patient experiences pain
}The more anodic restoration may corrode.
}
Saliva can be used as electrolytes
When metal touches, can create a current thru teeth
Patient will feel a shock
The more active elements will corrode
This is one of the reasons why metal will corrode in our mouth
- Galvanic Effect
-
____ _____
- E
- S
- Usually occurs ____ after ____ of a new ____ and generally it ____ ____and ____ in a few days. (___________________________.)
- Avoid placement of ____ ____ or ____ of different ____ ____.
- Dental exam with ___ _____.
- The Galv effect is _____ ______.
- What kind of
- What components in patients
- Some not at all patients are_____
- There are extreme ex that patients _____
- Explorer that we use to do the exam is ____
- If you touch a metal restoration with explorer, patient ________
}Patient specific
}Environment
}Sensitivity
}
}Usually occurs immediately after insertion of a new restoration and generally it gradually subsides and disappears in a few days. (Pulp irritated during prep and returns to normal stage after a couple of days.)
}
}Avoid placement of direct contact or proximity of different metallic restorations.
}Dental exam with metallic explorer.
}
The Galv effect is Patient Specific:
What kind of food does patient eat?
What components in patients saliva that are influencing this effect
Patients sensitive? Some not at all
These will effect galvanic
Most of time you have sensitivity first couple days. Pulp is irritated during prep. When pulp goes back to normal patient sensitivity goes away
There are extreme ex that patients cannot tolerate
Explorer that we use to do the exam is metal
If you touch a metal restoration with explorer, patient will jump
Electrochemical corrosion
Corrosion due to ______ properties
Oral environment ___ ___ ___ ____
Many years of ____
Metal can ____ overtime
Nothing is better then our own tooth structure
Our mouth is a ____environment
}Corrosion due to electrochemical properties
}Oral environment – warm, wet, acid and salty
}Many years of exposure
Metal can corrode overtime
Nothing is better then our own tooth structure
Our mouth is a hostile environment
Electrochemical Corrosion
Patient ____ - ___ ____
____ concentration - ______________causes corrosion
Decreased by formation of __________
We expect the materials that we put in patients mouth will be there for a long time
Patients diet and precense of oxides affects how the metal corrodes
If metal can form stable metal oxide, this will help _____________________.
}Patient diet - salt, sulfur
}Oxygen concentration - absence/presence of O2 causes corrosion
}Decreased by formation of stable metal oxides
}
We expect the materials that we put in patients mouth will be there for a long time
Patients diet and precense of oxides affects how the metal corrodes
If metal can form stable metal oxide, this will help protect metal underneath from further corroding
Electrochemical Corrosion
Can lead to:
D____
S___ R____
D_____ ____ properties & ____
M____ t____
B_____ c____
Corrosion products - may _________
Research found ____ correlation between____ _____ and ____ ____
Corrosion can lead to discoloration of metal restoration
Surface can become rough. It will ____ more ____
Sometimes patients will taste metal due to corrosion products
Patients will have get concerned
All materials we put in patients mouth are safe at this time
}Discoloration
}Surface roughness
}Decreased mechanical properties & appearance
}Metallic taste
}Biological concern
}Corrosion products - may accumulate in organs
}Research found no correlation between dissimilar metals and tissue irritation.
Corrosion can lead to discoloration of metal restoration
Surface can become rough. It will attract more plaque
Sometimes patients will taste metal due to corrosion products
Patients will have get concerned
All materials we put in patients mouth are safe at this time
Wear
Is the ___ of ____ ____
Types:
____wear – ____ _____
____ wear
____ wear
Types of wear
- •Abrasive: ___ what we have in ____
- •when we ____, it wears off tooth structure,
- •Two types
- ___ ____ __ : Patients ____. ____ to ___ tissue direct contact.
- when you chew the food gets bw your teeth. W
- hen teeth about to touch, you____.
- There is very ____ duration when
- Enamel is hardest material in our body.
- Dentin is ____
- Enamel will
- •____ ____ ____: there is ___ __ ______, ____ of media determines how much it wears over time
- •____ will wear off the ____ part
- ___ ____ __ : Patients ____. ____ to ___ tissue direct contact.
- •Fatigue
- •Corrosive
}Is the loss of anatomic contour.
}Abrasive wear – two-body abrasion; three-body abrasion
}Fatigue wear
}Corrosive wear
Types of wear
- Abrasive: mainly what we have in dentistry
- when we chew, it wears off tooth structure,
- Two types
- Two body abrasion: Patients clenches. Hard to hard tissue direct contact. when you chew the food gets bw your teeth. When teeth about to touch, you separate. There is very short duration when hard to hard teeth touches each other. Enamel is hardest material in our body. Dentin is similar to bone. Enamel will stand the wear better then other material
- Three body: there is media in between, composition of media determines how much it wears over time
- Hard will wear off the soft part
- Fatigue
- Corrosive
Types of Wear
- Abrasion: Usually its ___ part will wear off the ___part
- Fatigue: ____
- Sub surface
- Corrosive wear
- Oxidized layer
- Look at picture
Abrasion: Usually its hard part will wear off the soft part
Fatigue: over over and over again
Sub surface started to have crack
Whole layer will come off
Corrosive wear
Oxidized layer on surface is loosly there
New layer exposed
New oxidized layer forms
Look at picture
experiment to test amalgam and composites, the wear resistance of these against enamal
_____ wear much more then ____ and ____
Wear can happen to tooth itself
It can also happen when we put ________
Resin wear much more then amalgam and composite
Wear can happen to tooth itself
It can also happen when we put restorative materials there
Wear: of Dental restorative materials
Restorative material needs to be _______ and _______.
}Generally speaking, _____ proportional to ____
}No single laboratory test method can be used to_____________________
This is compositite restoration. There should be a lingual cusp right here but its been weared off completely during fcn.
It didn’t have high enough wear resistance
2 pictures : PFM: Porcelain fused to metal
Porcelain Can be very harsh to our dentition , it can wear off our tooth structure
Surface roughness: If its very rough, it can wear down tooth structure severely
Why does upper dentition have more wear than lower?
Sometimes we see the opposite
When hard to hard contact
One side wiill _____________
Once ______ is exposed, that tooth is not ________ as if there is all enamel covered
Increase hardness increase wearness
}Wear resistant
}Kind to opposing natural teeth
}
}Generally speaking, hardness is proportional to wear resistance;
}
}No single laboratory test method can be used to predict material’s clinical wear performance.
When we use a restorative material, we have to make sure it has enough wear resistance
It also has to be kind to existing tooth structure
This is compositite restoration. There should be a lingual cusp right here but its been weared off completely during fcn.
It didn’t have high enough wear resistance
2 pictures : PFM: Porcelain fused to metal
Porcelain Can be very harsh to our dentition , it can wear off our tooth structure
Surface roughness: If its very rough, it can wear down tooth structure severely
Why does upper dentition have more wear than lower?
Sometimes we see the opposite
When hard to hard contact
One side will fail dramatically
Once Dentin is exposed, that tooth is not as wear resistant as if there is all enamel covered
Increase hardness increase wearness
Rheological Properties: Viscosity (h)
- The___ of a fluid to___
- Equal to the ____ _____ divided by the ____ ____ ____
- or:
- η = τ / [dε/dt]
- ____ with increasing temperature
- ____ as the material sets
- Can be adjusted by varying the amount of____
- Lower viscosity, the ___ Material will flow
- Composites:
- •Flowable composites have ____ viscosity
- Impressions
- •We have ____ ANS ____
- We adjust amount of fillers to affect the viscosity
- When material starts to set, the viscosity of material will ____ gradually
}The resistance of a fluid to flow
}Equal to the shear stress divided by the shear strain rate,
or:
η = τ / [dε/dt]
}
}Decreases with increasing temperature
}Increases as the material sets
}Can be adjusted by varying the amount of fillers
}
Lower viscosity, the easier material will flow
Composites:
•Flowable composites have lower viscosity
Impressions
•We have low viscosity and high vviscosity
We adjust amount of fillers to affect the viscosity
When material starts to set, the viscosity of material will increase gradually
Viscosity (h)
- Can be used to measure the _____ of a material
- Viscosity as a function of ____
- When dental materials are taken out from refrigerator, we need to wait until it reaches _____ ____ so viscosity can ____ and the material will ___ better
- Different clinical indications for different viscosity material.
}Viscosity (h)
}Can be used to measure the working time of a material
}Viscosity as a function of time
}When dental materials are taken out from refrigerator, we need to wait until it reaches room temperature so viscosity can decrease and the material will flow better.
}Different clinical indications for different viscosity material.
Working time of material
Up to a point you can still work with the material
Once it is set the viscosity will increase gradually
Try to work within working time of the material
Sometimes we store material in fridge
When just come out of fridge, Temp is very low
That means the material has higher viscosity
Depends on usage
If you think flow will affect your work you hsould wait until it flows better (room T)
Viscoelasticity
- Materials that have ____ properties dependent on ___ ___ and exhibit both ___ and ___ behavior are termed _____.
- ____ strength when loading rate is ____
- ____ strain when applied stresses are of ____ duration
- Impression materials _____ removal
- Mechanical properties of material depends on
- If you load faster the material has higher strength
- If you load in shorter peiod of time, the deformation material will have is elastic
- After the load, the material will go back to its initial dimension
- We we remove impression materials we need to use a snap movement (quick)
}Viscoelasticity
}Materials that have mechanical properties dependent on loading rate and exhibit both elastic and viscous behavior are termed viscoelastic.
}Higher strength when loading rate is faster
}Reversible strain when applied stresses are of short duration
}Impression materials “snap” removal
}
Mechanical properties of material depends on how fast you load the material
If you load faster the material has higher strength
If you load in shorter peiod of time, the deformation material will have is elastic
After the load, the material will go back to its initial dimension
We we remove impression materials we need to use a snap movement (quick)
Solubility
- Solubility is the property of a solid, liquid, or gaseous chemical substance (called a solute) to ____ in a solid, liquid, or gaseous solvent to form a ____ solution of the solute in the solvent.
- Solubility is not to be confused with the ____ to ____ or ____ a ____, because the solution might occur not only because of____ but also because of a ____ ____.
- “Like dissolves like”
- Disintegration of the material
- Some of the material will dissolve into saliva
*
}Solubility is the property of a solid, liquid, or gaseous chemical substance (called a solute) to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent.
}Solubility is not to be confused with the ability to dissolve or liquefy a substance, because the solution might occur not only because of dissolution but also because of a chemical reaction.
}
}“Like dissolves like”
}Disintegration of the material
Some of the material will dissolve into saliva
- Sorption
- A ___ and ____ process by which one substance becomes ____ to another.
- Water sorption of a material represents the ____ of ___ ____ on the ____ and ____into the body of the material during____or while the restoration is in ____
- Degradation
- Dimensional change
- Can cause ____ and if material absorbs more water it can have ____change
- Can cause degredation and if material absorbs more water it can have dimensional change
}A physical and chemical process by which one substance becomes attached to another.
}Water sorption of a material represents the amount of water adsorbed on the surface and absorbed into the body of the material during fabrication or while the restoration is in service.
}Degradation
}Dimensional change
