Resin Composites I Flashcards
What is the mechanism of polymerisation an example of?
free radical addition
give the 4 steps of a free radical reaction
activation
initiation
propagation
termination
what are the clinical notes for polymerisation?
materials contract on polymerisation
reaction is exothermic
What does it mean for the clinician if the tertiary amine in a free radical reaction (polymerisation) is not fully used up?
poor colour stability (clear - brown)
Compared to silicates, acrylics are less?
prone to erosion
soluble
acidic
brittle
what sedative temporary filing material do acrylics interact with?
eugenol
give the definition of a resin composite
a combination of two chemically different materials with a distinct interface separating the components and having properties which could not be achieved by any of the components acting alone
what are the 3 key components of a resin composite?
resin matrix
filler
coupling agent
what is the resin matrix generally based upon?
methacrylate monomers
what is involved in the resin matrix to control viscosity?
TEGMA comonomers
why is a filler necessary?
to reduce shrinkage
name 3 common fillers in a resin composite
quartz, silica, glasses
why is a coupling agent necessary in a resin composite?
transfers the stresses generated under loading from the rigid and brittle filler to the more flexible and ductile polymer matrix
what must be used to set resin composite? what must be kept in mind
curing light; resin composite will set under operating light
name the 2 types of resin composites regarding handing characteristics
packable and flowable
