Resin II Flashcards
- Review - Dental Amalgam
- Composition
- ___
- ___ alloy powder
- There is thin film that has to break and different manufacturers make this differently
- ___ Cap
- ___ ___ part in before putting into triturator
- __ ___inside
- When you vibrate in triturator will break the thin film
- You can’t just take it and put it in triturator
- If not working, think about structure of the material
- After the reaction (mix materials) , the final products can look like this
- We talked about classifications of dental amalgam.
Review - Dental AmalgamComposition
Mercury
Amalgam alloy powder
There is thin film that has to break and different manufacturers make this differently
Twist Cap
Push top part in before putting into triturator
Med rod inside
When you vibrate in triturator will break the thin film
You can’t just take it and put it in triturator
If not working, think about structure of the material
After the reaction (mix materials) , the final products can look like this
We talked about classifications of dental amalgam.
- Review - Dental Resin Composites
- This what we use ___ in the clinic. It largely replaced amalgam already
- Resin matrix
- Inorganic fillers
- Treated with a ___ ___ (silane)
- Initiation system
- Inhibitor
- Pigments
Review - Dental Resin Composites
This what we use mainly in the clinic. It largely replaced amalgam already
Resin matrix
Inorganic fillers
Treated with a coupling agent (silane)
Initiation system
Inhibitor
Pigments
- Polymerization shrinkage
- Main problem with this material
- When material shrinks and we place it into prep, what will happen?
- It will ___ a ____
- Undesirable in oral cavity
- Oral cavity is hostile environment for materials
- Bacteria can get in and you will get ___ ___
- It will ___ a ____
Polymerization shrinkage
Main problem with this material
When material shrinks and we place it into prep, what will happen?It will form a gap
Undesirable in oral cavity
Oral cavity is hostile environment for materials
Bacteria can get in and you will get secondary decay
Polymerization stress
- Shrinkage also comes with ___
- When it shrinks it tries to get away from bonding structure
- Stress at interface bw tooth and material
- Those together lead to ____
- Microleakage
- May not see with our eye but the gap is there and then it can form
- ___ ___.
- filling failed
- ___ ___;
- Stain is just ____ and we can clean it
- ___ ___.
- May not see with our eye but the gap is there and then it can form
- ____ of the cusps
- Stress can pull the remaining tooth structure and create a ___
- Depends on how strong tooth is
- Enamel ____
- Remaining tooth structure ____ instead of ____ fractured
- This is bc tooth is not strong enough to bear the load
- ____ ____.
- This is very undesirable
- Patient comes to you with no symptoms. You find cavity with x ray. You fill the cavity and patient may start to have pain
- Can be caused by not being ___ very well
- There is a communication from outside world to inside tooth
- Can also be caused by____
- If there is a lot of stress, the tooth will feel it
- May get so bad that you have to change the restoration
- Stress can pull the remaining tooth structure and create a ___
Polymerization stressShrinkage also comes with stress
When it shrinks it tries to get away from bonding structure
Stress at interface bw tooth and material
Those together lead to microleakage
MicroleakageMay not see with our eye but the gap is there and then it can formsecondary de cay;
filling failed
marginal stain;
Stain is just esthetic and we can clean it
Deformation of the cuspsStress can pull the remaining tooth structure and create a crack
Depends on how strong tooth is
Enamel microcracks;
Remaining tooth structure fractured instead of remaining tooth structure fractured
This is bc tooth is not strong enough to bear the load
Postoperative sensitivity.
This is very undesirable
Patient comes to you with no symptoms. You find cavity with x ray. You fill the cavity and patient may start to have pain
Can be caused by not being sealed very well
There is a communication from outside world to inside tooth
Can also be caused by stress
If there is a lot of stress, the tooth will feel it
May get so bad that you have to change the restoration
Configuration-factor (C-factor)
- A. Put a material on top of a glass and this material shrink
- If it freely shrinks, it will shrink twd the ___ ____
- The other areas are all free so the material can ___ ___
- Not much stress in bw.
- B. Two glasses are set just like the walls of the tooth
- The wall cannot move
- If you put material in bw, it will try to shrink during polymerization
- But they can’t pull two walls together
- Can only shrink from___ ___
- This will create a ___
- We classify preps based on ____
- Depends on where decay is
- Occlusal filling: only free surface is ___ ___
- Veneer: ___ ___ ___ ___
- The more walls you have, when you put material in, the material will get ___ ____
- If the free surface is very small, this will create a lot of ___
- Calculation of C factor
- ___Surface/____surface
- Tells you how much ___ you wil get
Configuration-factor (C-factor)
A. Put a material on top of a glass and this material shrink
If it freely shrinks, it will shrink twd the bonded area
The other areas are all free so the material can shrink freely
Not much stress in bw.
B. Two glasses are set just like the walls of the tooth
The wall cannot move
If you put material in bw, it will try to shrink during polymerization
But they can’t pull two walls together
Can only shrink from free surface
This will create a stress
We classify preps based on shape
Depends on where decay is
Occlusal filling: only free surface is occlusal surface
Veneer: not that much stress
The more walls you have, when you put material in, the material will get more restricted.
If the free surface is very small, this will create a lot of stress
Calculation of C factor
Bonded Surface/Unbonded surface
Tells you how much stress you wil get
- Ways to overcome/offset polymerization shrinkage
- Currently we still use this material
- ___ ___ ____ matrix systems
- With new polymerization mechanisms
- ___ ___ resin systems
- We were using very big material
- This will reduce the ___ ____ (the double bond) in the whole molecules
- Add more i___ ___
- About ____ vol polymerization shrinkage
- Even when we do all that
- We just have to deal with it
- Less resin in material and ___ shrinkage will happen
- About ____ vol polymerization shrinkage
- How do we deal with it
- Use ___ ____
- Hold material in place
- If you cannot bond well, you can’t use this material!
- ___ ____technique
- We don’t put all of it into prep all at once
- We try to offset so of the stress
- Bond to ___ surfaces at a time
- Let it shrink
- Then add another layer
- Let it shrink
- When first layer shrinks, it will have a little more unbounded area
- It will give you more space
- Shrinkage will be offset by second layer
- This is another way to reduce stress, especially when you build up a large restoration
- Incremental also used because this a light curing material
- Light cannot penetrate ___ ___ thru material
- Resin composites are not transparent
- Max thickness we use is about __ mm
- Take our time to do restorations
- Takes ___ than amalgam
- We don’t put all of it into prep all at once
- Use ___ ____
- ‘Soft-start’ light curing process
- Curing lights have different modes
- Soft start:
- When we do polymerization, stress happens when the material has already ___ and is still ___ to ____
- In the beginning when material still manipulable, when the material shrinks, the molecules can still move so there will be____ stress.
- Stress offset by the movement
- Cure slow
- When the material can still move it will cure a little bit more
- When it doesn’t move anymore it will start to cure
- To offset polymerization stress
Ways to overcome/offset polymerization shrinkage
Currently we still use this material
Develop new resin matrix systems
With new polymerization mechanisms
Modify existing resin systems
We were using very big material
This will reduce the fcnal group (the double bond) in the whole molecules
Add more inorganic fillerAbout 2-3% vol polymerization shrinkage
Even when we do all that
We just have to deal with it
Less resin in material and less shrinkage will happen
How do we deal with itUse bonding agent
Hold material in place
If you cannot bond well, you can’t use this material!
Incremental application techniqueWe don’t put all of it into prep all at once
We try to offset so of the stress
Bond to two surfaces at a time
Let it shrink
Then add another layer
Let it shrink
When first layer shrinks, it will have a little more unbounded area
It will give you more space
Shrinkage will be offset by second layer
This is another way to reduce stress, especially when you build up a large restoration
Incremental also used because this a light curing material
Light cannot penetrate too deep thru material
Resin composites are not transparent
Max thickness we use is about 2 mm
Take our time to do restorations
Takes longer than amalgam
‘Soft-start’ light curing process
Curing lights have different modes
Soft start:
When we do polymerization, stress happens when the material has already set and is still trying to shrink
In the beginning when material still manipulable, when the material shrinks, the molecules can still move so there will be less stress.
Stress offset by the movement
Cure slow
When the material can still move it will cure a little bit more
When it doesn’t move anymore it will start to cure
To offset polymerization stress
Problems Caused by Resin Matrix
Elastic Modulus (GPa)
- When you load material we want it to deform the same way as the tooth structure
- Gold and Poreclain: ____ restorative material
- Take ___ to make
- More___
- Better!
- If restoration is___, you should go with this!
- Gold and Poreclain: ____ restorative material
- Amalgam and Resin: direct
- Acrylic resin is ___ base material and Silicone rubber is material for ___
- ___ elastic modulus
- Under small load, this will deform ___
Problems Caused by Resin Matrix
Elastic Modulus (GPa)
When you load material we want it to deform the same way as the tooth structure
Gold and Poreclain: indirect restorative material
Take longer to make
More expensive
Better!
If restoration is big, you should go with this!
Amalgam and Resin: direct
Acrylic resin is denture base material and Silicone rubber is material for impressions
Low elastic modulus
Under small load, this will deform greatly
Problems Caused by Resin Matrix CTE
How the material reacts to T change
Indirect is still ___ than direct
If filling is large the wall can become very ___ and under load this can ___
Patients will still have restoration but the tooth has fractured
Problems Caused by Resin MatrixCTE
How the material reacts to T change
Indirect is still better than direct
If filling is large the wall can become very thin and under load this can fracture
Patients will still have restoration but the tooth has fractured
Wear Resistance
Wear mechanism
____ wear is the main wear mechanism in dental composites
This is microfilled composites
When we eat the food wears off the restorations
The ___ will be worn off first bc its softer than the ____ inside
When there is not enough resin to hold filler in, the filler will fall out
Cycle starts again
The other mechanisms like ___ also contribute
During normal fcn, our tooth wear thru __ body wear (food in bw)
__ body wear happens with grinding
tooth to tooth
Parafcn
This will cause tooth to be worn severely
Wear Resistance
Wear mechanism
Abrasive wear is the main wear mechanism in dental composites
This is microfilled composites
When we eat the food wears off the restorations
The resin will be worn off first bc its softer than the fillers inside
When there is not enough resin to hold filler in, the filler will fall out
Cycle starts again
The other mechanisms like fatigue also contribute
During normal fcn, our tooth wear thru 3 body wear (food in bw)
2 body wear happens with grinding
tooth to tooth
Parafcn
This will cause tooth to be worn severely
- Hybrid: Microhybrid composites:
- ___s are just shed from surface
- Will look ___
- ___ ___ gloss very long
- Microfilled composites
- Particles are___ than the____ of light
- Even though it is exposed, it doesn’t scatter the light
- It is still very ___
- Nanoparticles:
- Whole fillers don’t get unplugged. It’s the___ ___
- Even though indiv particles get worn off, the surface can still keep really smooth
- Stay ___ ___
Hybrid: Microhybrid composites:
Particles are just shed from surface
Will look rough
Doesn’t keep gloss very long
Microfilled composites
Particles are smaller than the wavelength of light
Even though it is exposed, it doesn’t scatter the light
It is still very smooth
Nanoparticles:
Whole fillers don’t get unplugged. It’s the indiv particles
Even though indiv particles get worn off, the surface can still keep really smooth
Stay smooth longer
Wear Resistance
Consequences of severe wear
- Occlusion
- Lost normal ___ ___
- Without anatomy the chewing efficiency goes down
- Cusps enable us to chew better than a flat surface
- ___ ___of opposing tooth
- If one side gets lower the other side will keep coming up.
- This can create
- ___ ___
- If severely warned, the vertical dimension can become smaller
- Lost normal ___ ___
- Proximal contact
- ___
- Contact becomes open if its worned off
- Or posterior material can move in and those can also create occlusal interference
- ___ ___
- ___
- Avoid___ ___ ___area for this material
- Try to avoid the severely warned situation
Wear ResistanceConsequences of severe wearOcclusionLost normal dental anatomy
Without anatomy the chewing efficiency goes down
Cusps enable us to chew better than a flat surface
Supra-eruption of opposing tooth
If one side gets lower the other side will keep coming up.
This can create
Occlusal interference
If severely warned, the vertical dimension can become smaller
Proximal contactOpen
Contact becomes open if its worned off
Or posterior material can move in and those can also create occlusal interference
Mesial drift
Avoid high occlusal stress are for this material
Try to avoid the severely warned situation
Wear Resistance
- With high load, you can’t see ___ ___ anymore (its all warned down
- In comparison, amalgam will hold the tooth structure___ than composites
- Looks the same after __ years
Wear Resistance
With high load, you can’t see marginal ridge anymore (its all warned down
In comparison, amalgam will hold the tooth structure better than composites
Looks the same after 7 years
Mechanical Properties
- ___ strength, ___strength and ___ strength are adequate for dental restorations if ___ ___
- Higher mechanical properties are associated with ___ ___ ___ ___
- This is why manufacturer tried to put as much material as possible into the resins
- Leads to better mechanical properties
- Use high filler loading material whenever possible
- This is why manufacturer tried to put as much material as possible into the resins
- Higher mechanical properties also associated with higher degree of ___ of ___ ___
- Resin matrix will be stronger if the ___ is more ____
Mechanical Properties
Compressive strength, tensile strength and flexural strength are adequate for dental restorations if handled properly.
Higher mechanical properties are associated with higher inorganic filler loading.This is why manufacturer tried to put as much material as possible into the resins
Leads to better mechanical properties
Use high filler loading material whenever possible
Higher mechanical properties also associated with higher degree of conversions of resin matrix.
Resin matrix will be stronger if the polymerization is more complete
Factors Influencing Polymerization
- Air
- ___ ___ ___
- O2 in the air will _____ polymerization
- We talked about the layering technique
- Are the layers bonded to each other?
- They are____
- Bc of O2 inhibited layer, they are not ___ ____ on the surface
- That works for the ___
- Are the layers bonded to each other?
- On the last layer there will be this O2 inhibited layer there
- When you finish restoration you may feel the top is ___
- When you polish, this layer will get ____
Factors Influencing PolymerizationAir
Oxygen inhibited layer
O2 in the air will inhibit polymerization
We talked about the layering techniqueAre the layers bonded to each other?
They are bonded
Bc of O2 inhibited layer, they are not fully polymerized on the surface
That works for the better
On the last layer there will be this O2 inhibited layer there
When you finish restoration you may feel the top is sticky
When you polish, this layer will get removed
- Eugenol
- Long history of using this material as a ___ material
- When tooth gets irritated, we use eugenol containing material to sooth the effects
- We hope the pulp can __ ___ and is still alive
- But eugenol does ___ ____
- Wont allow it to polymerize as ___ as ____
- Think about this when you do a termporization for your prep
- Sometimes we can’t finish prep in one setting
- Have to add ___ and let the patients go
- If you use eugenol containing material to temporize, it will affect polymerization of ___ later on
- If you are still going to ___ that ___ ___, then its probably okay
- If you are not cutting and about ready to do fillings, probably ___ a ___ ___.
- Sometimes we can’t finish prep in one setting
- Light source
- ___
- ___
- How far away are you from surface you are about to cure
- ___ time
- ____ s
- You need to cure adequately to get best possible polymerization
- Wavelength
- Associated with the ___ system
- Different initiation systems.
- Each comes with different wavelength.
- The most commonly used one have wavelengths in ___light range
- That’s why when you see curing light it shines blue
- That material has tendency to change color over time
- Manufacturers are trying to change the initiation sys to improve the esthetics
- The color stability
- They are using different initiation systems and that may not be compatible with light source you are using
- Right now we are using LEDà very ____wavelength
- May not be compatible with___ you are using
- Shade
- Influences ___ ____
- Darker shade will reflect light ___ so will ___ ___
- You will need a ___ layer than translucent shade
- Keep these factors in mind to get best possible polymerization
- Fully polymerized direct resin composite has a degree of conversion of about ____%.
- About 60-70% of the double bond is ____
- This is best we can get from ____ restorative material
- If this material is cured indirectly, it can achieve a little bit ___
- Note: After 5s the material is hard. Patient wont know
- Service time of this restoration will be much less then if you cure it fully
- Even if you cure fully, its only 60%
- Saves dentist time but that is not responsible
Eugenol
Long history of using this material as a soothing material
When tooth gets irritated, we use eugenol containing material to sooth the effects
We hope the pulp can calm down and is still alive
But eugenol does inhibit the polymerization
Wont allow it to polymerize as fully as possible
Think about this when you do a termporization for your prepSometimes we can’t finish prep in one setting
Have to add temporary and let the patients go
If you use eugenol containing material to temporize, it will affect polymerization of composite later one
If you are still going to cut that layer off, then its probably okay
If you are not cutting and about ready to do fillings, probably choose a different material
Light source
Intensity
Distance
How far away are you from surface you are about to cure
Curing time
20-40 s
You need to cure adequately to get best possible polymerization
Wavelength
Associated with the initiation system
Different initiation systems.
Each comes with different wavelength.
The most commonly used one have wavelengths in blue light range
That’s why when you see curing light it shines blue
That material has tendency to change color over timeManufacturers are trying to change the initiation sys to improve the esthetics
The color stability
They are using different initiation systems and that may not be compatible with light source you are using
Right now we are using LEDà very narrow wavelength
May not be compatible with material you are using
Shade
Influences light penetration
Darker shade will reflect light more so will penetrate less.
You will need a thinner layer than translucent shade
Keep these factors in mind to get best possible polymerization
Fully polymerized direct resin composite has a degree of conversion of about 60-70%.
About 60-70% of the double bond is polymerized
This is best we can get from direct restorative material
If this material is cured indirectly, it can achieve a little bit more.
Note: After 5s the material is hard. Patient wont know
Service time of this restoration will be much less then if you cure it fully
Even if you cure fully, its only 60%
Saves dentist time but that is not responsible
