Restorative Resin Based Composite Materials Flashcards
What’s the definition of a composite
Compound of 2 or more distinctly different materials with properties that are superior or intermediate to those of individual constituents
Are teeth composites
yes- the two materials are enamel and dentin
What is the organic matrix of enamel
enamelin
What is the inorganic matrix of enamel
hydroxyapatite
What is the organic matrix of dentin
collagen
what is the inorganic matrix of dentin
hydroxyapatite
What are the advantages of resin composite
- Esthetic (emulates tooth structure)
- Fracture resistant
- Wear resistance
- Command set- can sculpt and carve
- Conservative preparation (most important advantage)
- Low thermal conductivity (compared to amalgam)
- Radiopaque
What are the disadvantages of Resin Composite
- Polymerization shrink ~2-4%
- Requires dental bonding agents (DBA) and light curing (extra step)
- lengthy placement
- RD required
- Marginal leakage and wear resistance (these are no longer issues but they once were)
- Water sorption- Absorbs H2O causing discorloration and swelling of the restoration
What are the 4 structural components of resin composite
- polymer matrix
- Inorganic filler
- Coupling agent
- Initiator
What is an organic polymer matrix is a __phase to which other materials are __
a continuous phase…added
The organic polymer matrix is made out of
resin monomers
What are the highly viscous resin monomers (2)
Bis-GMA
UMDA
Bis-GMA and UMDA are (high/low) MW monomers
high
What are the low MW monomers with low viscosity
TEG-DMA and Bis-EMA
Which two monomers listed are low shrinking monomers
Bis-EMA and oxybismethacrylate
Inorganic fillers are __ or __ based
glass or quartz
What are the three most common inorganic fillers
zirconium oxide, aluminum oxide, and silicon dioxide
Filler particles are added to…
the organic matrix
Filler is added to the organic matrix in order to improve the
physical properties of the resin
In general the (greater/less) the filler the the better the properties of the resin- but there is a limit
greater
Why would excess filler lead to an unfavorable resin
would become too viscous
Benefits of filler particles
- Improves color stability
- Reduces H2O sorption
- Improves compressive and tensile strength
- Reduces coefficient of thermal expansion
- Reduces polymerization shrinkage
- Improves wear resistance
What is another name for a coupling agent in resin
silane
What is the role of coupling agent/silane
keeps everything together- it oats the filler particles to promote adhesion to the matrix
Other than adhesion of filler particles to the matrix, what is another purpose of coupling agents
-provide hydrolytic stability meaning it is more resistant to H2O penetration
The Organic matrix is (weak/strong) and the filler is (weak/strong)
weak…strong
What is an initiator
something that activates the polymerization reaction
What are the two different types of polymerization reactions
chemical and light
What is the wavelength of light necessary to perform a light initiated polymerization
460-480 nm (blue light)
What is the initiator and activator of a chemically activated system
- Benzoyl peroxide initiator
- Aromatic tertiary amine activator
What is the initiator and activator of a light activated system
- Alpha diketone camphorquinone intitiator
- Aliphatic teriary amine activator
What is the advantage of aliphatic amines over aromatic amines
aliphatic have better color stability
Light reactions occurs due to the formation of __
free radicals
An increase in the thermal expansion coefficient can lead to
a greater likely hood of micro leakage
What are the three types of resin based on how they are handled
- Flowable
- Packable
- Compactable
(Compactable/Pactable/Flowable) are no longer available
packable
Enhanced flowability of the resin leads to an increased risk of __
porosities
Use alcohol to prevent resin from sticking to the instrument- what happens if too much alcohol is used
dilution of resin
What is the refractive index of composite
1.5 which is similar to tooth structure –> nice esthetics
Resins are also classified based on their
filler particle size
Size of a macrofill resin
10-100 um
Size of a midfill resin
1-10 um
Size of a minifill resin
0.1-1 um
Size of a microfill resin
0.01-0.1 im
Size of a nanofill resin
0.05-0.01 um
Size of a hybrid resin
mixture of different sized particles
Most common resin compositite is ….
nanohybrids (nanofill + hybrid)
What were the issues with macrofilmed (traditional) resin
Pronouced plastic deformation , micro leakage, H2O sorption, surface staining, etc. These particles were too big and allowed access to the matrix
What are the pros and cons of microfilmed resins
- Highly polishable- great esthetics for Class V
- Low strength and higher water sorption
Why are hybrid composites beneficial
because having different particle sizes allows for the highest levels of filler loading
Which polishes better microfilm or hybrid
microfill
Which is stronger microfill or hybrid
hybrid (good for posterior regions)
Micro-hybrid or nanofilled resin combines the advantages of __ and __
microfilled and hybrid resin
Packable resins have a (high/low) viscosity
high
Packable resin can survive (more/less) wear than amalgam
more
Advantages of packable resin
- Can be placed in bulk
- Can be carved
- Less polymerization contraction
- High dept of cure
Disadvantages of packable resin
- Marginal adaptation= more difficult
- Harder to polish
- High surface roughness
(T/F) Flowable composite is more elastic and flexes with the tooth
t
Flowable composite is recommendend for…
- Small class V
- Sleaants
- Liner under C factor prep
Any light cure with a wavelength range of __ can be used
400-500nm
How well a composite is polymerized depends on what factors
- Wavelength og LCU
- Intensity of light
- Exposure time
- Distance from tip to composite
- Shade of resin
