Clinical Aspects of Resin Composite Flashcards
Ingredients in resin composite?
◦ Matrix ◦ Fillers ◦ Coupling agents ◦ Initiators and accelerators ◦ Pigments/ Optical modifiers
Classification of composite is based on?
filler size
What are the filler types?
Traditional types
Recent types
Trad:
macro-filled/ small particle/hybrid/micro-filled
Recent:
Nano-hybrid/ nano-filled
Ingredients in resin composite: Matrix
What is it?
Divide into …./….. , give examples?
If the composite is made up of just resin matrix it is known as unfilled resin
Phase that polymerizes to form a solid mass. Absorbs water, stain and discolours. Least wear resistance.
Viscous monomers- Bis GMA/ UDMA
Dilutents - TEGDMA/HEMA
Unfilled resin
Ingredients in resin composite: Fillers
Types of fillers?
If a composite is made of the resin matrix and filler particles, its called?
what influence does filler size have?
Silica particles / Quartz / Glass (Ba, Sr, Zr)
Filled resin
Determines surface smoothness, larger the particle size the rougher the surface
Ingredients in resin composite: Coupling agents
Coupling agent is a-
Silane bonds to the
Methacrylate end polymerizes with
bifunctional molecule
hydroxyl group of filler particles
resin
Ingredients in resin composite: Optical modifers/ pigments
What are the benfits?
In addition?
Provide translucencency and opacity
Tend to mental oxide
-titanium dioxide
-aluminium oxide
Addition on stablilisers, radio opaque materials (e.g baron, zinc)
Light activated composite-
For light activated materials:
Light source:
free radical reaction
Photo initiator- camphorquinone Amine accelerator ( diethy-amino-ethyl-methacrylate) Polymerization inhibitor-hydroquinone (prevents setting during storage)
Blue light emitting diode
Plasma arch light
Argon laser
Halogen light
Short comings:
Polymerisation shrinkage
Technique sensitive- high affect by moisture
Doesn’t bond to tooth- needs a bonding agent
Shrinkage-
Development of gap, microleakage
Leads to secondary caries, staining or sensitivity
Bonding
Total etch enamel + Dentine for 15 sec, was for at least 15 sec. Dry but don’t over dry gently dry for 5-10 sec resulting in a frosty white appearance
Etch is-
How does it affect Enamel:
How does it affect Dentine:
37% phosphoric acid
Creates a micro porous layer
Increases surface area
Increases wettability
Increases surface energy
Removes smear layer
Unblocks and widens dentinal tubule orifices
Exposes network of collagen fibre
What is bonding agent? its important to be aware of?
Different generations of bonding agents, what is the most common?
What is the hybrid layer? and what is it responsible for
Chemical that allows composites to adhere to tooth ( enamel And dentine)
Need to be aware of the differences between enamel and dentine structures
Common used 2 step technique- total etch followed by prime+bond
is the zone of resin interlocking with demineralised dentine surface. The hybrid layer is responsible for micromechanical bonding tooth and resin
Light curing:
Light of 450-490 nM
Sets material when you are ready
Limited depth ofcure- 2mm max, less for dark composites
Incremental build up
Avoid joining one enamel wall to another
Increment <2mm
Oxygen inhibition layer- glossy film of uncured resin
