9/12: Lecture 4 - Biomaterials Flashcards
What is the most used restorative material?
Dental composite resin
What are 3 components of composite resin?
- Organic resin matrix
- Inorganic filler aprticles
- Coupling agent
What is the organic resin matrix?
difunctional monomer with 2 reactive ends for cross-linking
What are the functions of the organic resin matrix?
Hold composite material together, allows modality, and will polymerize when activated to harden into solid material
What are examples of organic resin matrix?
Bis-GMA and UDMA
TEGDMA
What does TEGDMA act as?
Dilutent and is correlated to polymerization shrinkage
Where are the of inorganic filler particles located? What do they do there?
dispersed into matrix to reinforce its mechanical properties
What are the functions of inorganic filler particles?
Reinforce matrix, decrease shrinkage, decrease thermal expansion, control viscosity, decrease water sorption, increase radiopacity
- different sizes and distrubutions (hybrid)
What is the function of the coupling agnet?
binds filler particles to resin matrix
What is the coupling agent made of?
Silane
What does the coupling agent allow for?
better stress distribution, improves mechanical properties, and decreases water sorption along filler-resin interface
What is the purpose of the activator-initiator system?
Monomers need to be converted to polymers
What are activators?
Light (blue light)
Heat
Tertiary amine (CHEMICAL)
Mnemonic: A Loud Team, I Can’t Beat
Activators: Light and Tertiary Amine, Initiators: Camphorquinone and benzoyl peroxide
What is the function of activators?
Convert initator into free radicals
What are initators?
Benzoyl peroxide (CHEMICAL)
Camphorquinone (LIGHT CURED)
Mnemonic: A Loud Team, I Can’t Beat
Activators: Light and Tertiary Amine, Initiators: Camphorquinone and benzoyl peroxide
What happens once initiators are in the free radical?
Addition reaction begins
What is the purpose of bulk fill?
can restore in a single increment up to 4-5 mm, for posterior (class 1 and 2)
What are the advantages of bulk fill?
increased depth of cure, reduced polymerization shrinkage (designed to minimize shrinkage), improved adaptation, and simplified technique
What are disadvantages of bulk fill?
more translucent (body), cannot mimic layering of tooth, needs higher output in curing light
What kind of resin matrix do bulk fills use?
UDMA resin matrix
How do bulk fill composites modify their UDMA resin matrix?
adding aromatic groups to make it a fragmentation monomer = less polymerization shrinkage
What initator do bulk fills use?
alternative photoinitiator (ivocerin)
How does the alternative photoinitiator (ivocerin) compare to camphorquinone as an initator?
Alternative photoinitator has higher absorption across more wavelengths compared to camphorquinone
What are the two types of bulk fill composites?
Can be flowable bulk fill (only replace dentin and acts as a base for regular composite on occlusal) or full body bulk fill (dentin and enamel, use subtractive technique)
What are the benefits of regular composite?
many applications, versatile, layering technique, more esthetic
How do the filler particles compare in regular composite?
More filler particles (80-85%) and usually hybrid and smaller in size
