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60 Cards in this Set
- Front
- Back
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Dental Composite
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Restoration resulting from the mixture of ceramic reinforcing filler particle in a monomer matrix that is converted to a polymer on setting.
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Microfilled
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0.4 mm silica (anteriors)
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Microhybrid
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0.4 mm silica + 0.5 - 1.00 mm glass (posteriors)
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All-purpose
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anterior or posterior use
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Anterior
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excellent shade selection and polishability
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Posterior
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imporved wear resistant, higher strength
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Two-paste
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dual- and self cured systems (cores, resin cements)
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Sinlge-paste
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ligth cured systems
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Flowable
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direct syringe delivery
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Packable (condensable)
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unit dose, packable like amalgams
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Composition of Composites
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- Resin matrix (bis-GMA, UDMA)
- Inorganic filler particles - collidal silica,glass, zirconia - Silane Coupling agent - 3-methacryloxypropyl-trimethoxysilane - chemically joins resin to filler particles - Accelarator-initiator system (ligth cured)organic amine, camphoroquinone - Pigements |
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Radiometer
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measures the light output of curing light
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Polymerization shrinkage
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can cause gap or residual stress that can lead to debonding or fractured tooth structure along tooth-restoration interface
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Water sorption
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may affect shade match, may offset some residual stress
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Water solubility
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inorganic ions and organic molecules leach from surface and bulk of composites
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Radiopacity
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greater than dentin, some greater than enamel, 1/3 to 1/2 that of amalgam
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Thermal expansion
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greater then tooth structure, difference leads to residual stress and debonding
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Hardness
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resistance to indentation less than tooth structure and amalgam, may affect wear resistence
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Compressive strength
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greater strength means greater resistance to bulk fracture
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Flexure strength
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greater strength means greater resistance to marginal failure
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Wear resistance
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need resistance to contact and non-contact wear, less wear resistence (more wear) than amalgam or enamel, 3-20 um/year
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which one is more wear resistant:
- posterior - anterior |
posterior
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which one is more wear resistant:
- packable - all-purpose - flowable |
packable > all-purpose > flowable
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wear depends on what
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- particle size
- amount of particles - quality of silane coupling - size and location of restoration |
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Which areas are least wear resistant
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large areas on molars
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Histology of composites
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potential irritants to pulp
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what can be used for pulpal protection
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Liners:
- calcium hydroxide - glass ionomer - hybrid inonomer - compomer |
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what material should be avoided when using composites
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ZOE
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How does ZOE affects the composites
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it inhibits polymerization
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Dental composites are combination of _____ materials.
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2
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What materials were used as esthetic materials before dental composites were used
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- acrylic materials
- Silicate cements |
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Disadvantages of Acrylic materials
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lacked clinical efficacy
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Acrylic materials lacked clinical efficacy due to what:
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- high coefficient of thermal expansion
- recurrent caries - excessive polymerization shrinkage |
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Disadvantages of Silicate cements
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- they dissolved quickly
- required frequent replacement |
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Diluent
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is added to composites to control the viscosity of the final product
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Matrix
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important because it is the phase that polymerizes to form a solid mass which bonds to the tooth structure.
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Short comings of matrix
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- weak
- low wear resistance - absorbs water - stains - discolors |
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Fillers
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naturally occuring quartz material (sand)
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characteristics of fillers
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- strong
- hard - chemically stable in the oral environment |
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What determines the smoothness of dental composite
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filler size
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The larger the size of the filler the rougher the surface of the filling
True or False |
true
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3 categories of Filler
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1) Macrofill
2) Microfill 3) Hybrid (blends) |
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Filler evolution
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softness or hardness of the filler
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softer particle wears down quickly
True or False |
True
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Harder particle wears at (slower/faster) rate and has a (less/greater) abrasion resistance
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slower / greater
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As filler content ________, resin content ________.
a) increases, decreases b) decreases, increases c) increases, increases d) decreases, decreases |
a) increases / decreases
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Increase filler content decreases polymerization shrinkage and the coefficient of thermal expansion becomes more like tooth structure.
True or False |
True
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Increase filler content increases hardness and abrasion.
True or Fals |
True
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Silane Coupling Agent
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bonds the filler particles to the resin material
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How does polymerization of composites occurs?
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- light activation (most common)
- chemical activation |
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chemical cure materials require what?
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base and catalyst
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Polymerization shrinkage
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can cause gap or residual stress that can lead to debonding or fractured tooth structure along tooth-restoration interface
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Which one of the Ionomers have chemical bond
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Glass Ionomer
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Which one of the Ionomers have chemical and micro-mechanical bond
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Hybrid Ionomer (Resin Modified Glass Ionomer)
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Which one of the Ionomers have micro-chemical bond
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Compomers
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Which one of the Ionomers have the highest fluoride release
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Glass Ionomer
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Which one of the Ionomers have the medium fluoride release
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Hybrid Ionomer
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Which one of the Ionomers have the lowest fluoride release
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Compomers
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Compositon of Glass Ionomer
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Fluoroaluminosilicate glass
Polyacrylic acid Water |
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Compositon of Hybrid Ionomers
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- Polycarboxylic acid with methacrylate groups
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