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What are the 4 most commonly used direct-placement esthetic materials?
- composite resin
- glass ionomer cement
- resin-modified glass ionomer ( or hybrid ionomer)
a mixture of two or more materials with poperties superior to any single component
tooth-colored materials that are used in both the anterior and posterior parts of the mouth
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?
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
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:
What is used to provide a stronger bond between the organic fillers and the resin matrix?
What coupling agent is used in resins?
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?
Which type of cured composite resin are two-paste systems supplied in jars, syringes, or cartridges? (self-cure)
What are the two 'pastes' in chemically cured composite resins?
base and catalyst
What material makes up the base in chemically cured composite resins?
- benzoyl peroxide=initiator
What material makes up the catalyst in chemically cured composite resins?
- tertiary amine=activator
What is the working time for chemically cured composite resins before it becomes too stiff to manipulate?
What are the most common type of composite resin used in private practice?
What is it called wen side groups of adjacent polymer chains share electrons, form COVALENT bonds that link the chains together?
In general it is recommended that the composite be placed in increments no thicker than __ mm when using light-cured composite
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?
- 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?
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
What type of composites are strong composites that can be polished to a high shine, and they retain that shine better than earlier composites?
LOW-viscosity, light cured resins that may be lightly filled, or more heavily filled
true or false. nano-sized fillers are being used in flowable composites now also
______ 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.
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
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
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