What are the 4 most commonly used direct-placement esthetic materials?
composite resin
glass ionomer cement
resin-modified glass ionomer ( or hybrid ionomer)
compomer
a mixture of two or more materials with poperties superior to any single component
composite
tooth-colored materials that are used in both the anterior and posterior parts of the mouth
composite resins
What are the 3 things that composite resins are mostly composed of?
organic resin (polymer) matrix
inorganic (silica) filler particles
joined together by silane coupling agent
What is the most commonly used resin for the matrix of composites? What is another resin that is used for composite matrix?
bis-GMA
bisphenol-A
What does the addition of filler particles do to the organic resin?
makes it stronger and more wear resistant
true or false. Fillers are also added to resin to control the handling characteristics of the composite resin and to reduce the shrinkage that occurs when the resin matrix polymerizes or sets
true
What are the fillers used in composite resins?
inorganic silica particles
What are two ways that silica may be used in?
crystalline form - quartz
noncrystalline form - glass
What are 5 materials that are used to make the composite resin restoration show up on radiographs? (radiopaque)
ions of:
barium
strontium
boron
zirconium
yttrium
What is used to provide a stronger bond between the organic fillers and the resin matrix?
coupling agent
What coupling agent is used in resins?
silane
What are the 4 main purposes of filler components in composite resins?
make organic resin stronger
more wear resistant
control handling characteristics
reduce polymerization shrinkage
The higher the amount of filler content in a composite material=?
stronger and more wear resistant
Why do we want smaller filler particles on the resin surface?
because smaller filler: cause fewer voids that contribute to wear
be packed closer together
smoother surface
What 2 things is good adhesion of the two coupling agents necessary for?
to minimize loss of filler particles
and to reduce wear
monomers join together to form what?
polymers
Which type of cured composite resin are two-paste systems supplied in jars, syringes, or cartridges? (self-cure)
chemically cured
What are the two 'pastes' in chemically cured composite resins?
base and catalyst
What material makes up the base in chemically cured composite resins?
composite
benzoyl peroxide=initiator
What material makes up the catalyst in chemically cured composite resins?
composite
tertiary amine=activator
What is the working time for chemically cured composite resins before it becomes too stiff to manipulate?
2 minutes
What are the most common type of composite resin used in private practice?
light-cured composites
What is it called wen side groups of adjacent polymer chains share electrons, form COVALENT bonds that link the chains together?
cross-linking
In general it is recommended that the composite be placed in increments no thicker than __ mm when using light-cured composite
2mm
Why do interproximal areas need to be cured longer with the light-cure composite?
because of the more difficult access of the area to the direct path of light
Do lighter or darker shades of composite need more light curing time? Why?
darker
the light is more readily absorbed by the dark color, and does not transmit through the material as readily as through light-colored materials
What has helped make composite restorations more durable, leak less, polish better, and match the teeth better?
over time: filler particle size has become smaller and smaller
number of fillers in resin has increased
polymerization shrinkage has decreased
What type of material contains both macrofillers and microfillers with filler particles ranging from .1-3 micrometers? Which is why it has this name?
hybrid composites
the combination of macro and microfillers in hybrid composites produces what?
a strong composite that polishes well
What are the particle sizes in nanohybrids?
.005 to .020 micrometers
shrinkage has been reduced from __% with earlier composites to less than __ % with some of the nanohybrids
3
1
What type of composites are strong composites that can be polished to a high shine, and they retain that shine better than earlier composites?
nanohybrids
LOW-viscosity, light cured resins that may be lightly filled, or more heavily filled
flowable composites
true or false. nano-sized fillers are being used in flowable composites now also
true
______ composites are well suited for use in conservative dentistry (preventive resin restorations), where they readily flow into the narrow preparations created with small burs and diamonds or air abrasion. They may be used in place of pit and fissure sealants.
flowable
Why are flowable composites more wear resistant than that of most lightly filled sealants?
because their filler content is higher
Why are flowable composites so useful as liners in large cavity preps?
because they adapt to the preparation better than more viscous materials such as hybrid and packable composites
What allows flowable composites to cushion stresses created by polymerization shrinkage or heaby occlusal loads when they are used as an intermediate layer under hybrid and packable composites?
their low elastic modulus
flowable composites are useful for restoration of class _____ noncarious lesions caused by toothbrush abrasion, acid erosion, or occlusal stresses such as bruxing that lead to flexing of the tooth
V
Why aren't flowable composites used in areas of high occlusal function or high wear?
because they shrink more when polymerized, wear more readily, and are weaker than hybrids