Term
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Definition
materials made of large, long molecules formed by chemically reacting monomers |
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Term
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Definition
chemical reaction linking monomer together to form a polymer |
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What are thermoplastic polymers? |
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Definition
can be heated and shaped, remelted and reprocessed |
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Term
What are thermoset polymers? |
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Definition
-cross-linked structure -Cannot be heated and molded, need to be in final shape when polymerization occurs. |
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What are some examples of thermoset polymers? |
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Definition
dental resins/composites are thermoset polymers |
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Term
What do heat activated acrylic resins use as the initiator? The activator? |
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Definition
-benzoyl peroxide as the initiator -heat is the activator (powder/liquid system) |
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What usually requires heat activated acrylic resins? |
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Definition
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What do chemically activated acrylic resins and composite materials commonly use as the initiator and activator? |
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Definition
initiator- BPO activator- a variety of chemicals (tertiary amines) |
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Term
What are chemically activated materials? |
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Definition
usually a powder and liquid mixed together |
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What are chemically activated materials used to create? |
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Definition
temp crowns, impression trays, orthodontic retainers |
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Term
How do light activated work? |
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Definition
activator absorbs light and then reacts with the initiator (dental composites) |
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How does Dual-cure activated work? |
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Definition
set by chemical reaction and light Material that cannot be reached by light sets by chemical rx |
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Term
What does an inhibitor do? |
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Definition
destroys free radicals delaying polymerization allowing for more working time |
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Term
What is a commonly used inhibitor? |
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Definition
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Term
are polymers with unfilled resins suitable for restorative use? |
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Definition
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Why aren't polymers with unfilled resins suitable for restorative use? |
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Definition
1.polymerization shrinkage 2.coefficient of thermal expansion 3.strength and abrasion resistance of polymeric materials |
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Term
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Definition
polymers shrink – bonding materials reduce gaps in restoration |
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Term
Coefficient of thermal expansion: |
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Definition
unfilled resins = 2 to 10 times greater than tooth structure |
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Term
Strength and abrasion resistance of polymeric materials: |
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Definition
unfilled resins unable to withstand occlusal forces |
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Term
How are plastics useful for a cavity prep? |
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Definition
Plastics are useful because they can be placed in a cavity prep and molded and shaped in the mouth |
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Term
Who developed the first dental composites? |
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Definition
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Term
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Definition
strong ceramic materials added to polymer (silica and glass materials) |
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Term
What do silane coupling agents do? |
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Definition
Enables adhesive materials to bond ceramic restorations to tooth structure |
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Term
BLANK improve strength, have low thermal expansion |
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Definition
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Term
What happens if all filler particles are not properly wetted by liquid monomers? |
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Definition
voids and gaps between the filler molecules result |
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Term
Are most composites light activated? |
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Definition
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What are the components of dental composites? |
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Definition
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What is the matrix of a dental composite? |
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Definition
-polymer (bis-GMA) or a similar monomer |
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Term
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Definition
organic chemical added to the matrix to control the viscosity of the final product |
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Term
What does the matrix do? What is bad about it? |
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Definition
-it is the phase that polymerizes to form a solid mass and bonds to the tooth surface -weak and absorbant |
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Term
What are fillers? What do they do? |
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Definition
-engineered glass materials mixed with polymer to form a paste -improve strength |
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Term
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Definition
larger particles make a rougher surface |
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Term
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Definition
evolved into softer particles that stay embedded in matrix |
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Term
Filler content(amount of filler) |
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Definition
when filler content increases shrinkage decreases when polymerized |
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Term
What are polymerization systems used for? |
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Definition
the convert the matrix filler paste to a solid composite material **used by all dental composites** |
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Term
Chemically activated polymerization systems |
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Definition
2 paste systems Limited amount of working time |
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Term
What are light activated working materials? What is the working time determined by? |
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Definition
-single paste mixed by manufacturer -light source can damage eyes -working time determined by user (have virtually replaced chemical activated |
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Term
What are macrofilled composites? Particle size? Filler content? |
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Definition
-quartz material -particle size 10-25 um -filler content is 70-80% by weight |
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Term
What is a down side to macrofilled composites? What are they used for? |
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Definition
-Rougher causes greater plaque accumulation and staining -Not used anymore except in ortho |
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Term
What is the size of microfilled composites? |
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Definition
.03-.5 um particle size 40-50% filler (silica) |
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Term
What are some good things about microfilled composites? |
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Definition
-Polish very smooth and lustrous -Increased thermal expansion and low strength -Good for class V restorations because of high MOE -Flex with tooth |
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Term
What are hybrid composites? |
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Definition
wider range of particle sizes .5-1 um in size (.1-3 um) 75-80% filler content by weight |
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Term
What are some good things about hybrid composites? |
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Definition
-strong, polish well -used for many restorations |
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Term
What are nano sized particles? |
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Definition
improved hybrid composites that have improved strength and shrinkage -100 times smaller than the thickness of a human hair |
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Term
How can a restoration be made to look more natural? |
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Definition
Layering materials with different shades and translucencies |
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Term
What are opaque materials used for? |
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Definition
to prevent underlying color from showing through |
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Term
What kind of situations are composites good for? |
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Definition
Low to moderate stress situations. Not good for cusp replacement. |
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Term
Why are ceramic restorations so expensive? |
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Definition
have to be made outside of the mouth |
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Term
What are some factors effecting the placement of composites? |
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Definition
-depth of cure -incremental addition |
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Term
How does the depth of cure effect the placement of composites? |
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Definition
-thickness of material to be cured -Pulpal irritation occurs if composite material nearest pulp is not fully cured. |
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Term
WHat is incremental addition? |
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Definition
placing composites in layers allowing for shrinkage toward the tooth |
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Term
What are the first 5 steps in placing a composite restoration? |
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Definition
1.Diagnose lesion 2.Determine shade(s) needed 3.Isolate area to be treated 4.Cut the preparation 5.Determine the need for a liner |
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Term
What are steps 6-13 of placing a compositre? |
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Definition
6.Etch, prime, place, and cure adhesive 7.Incrementally place and cure composite 8.Finish 9.Check for interproximal contacts 10.Examine for voids and marginal defects 11.Polish 12.Remove rubber dam 13. Check occlusion |
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Term
How do composites feel to an explorer? |
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Definition
Feel a bit softer than enamel to a sharp explorer |
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Term
How does the filler material of composites effect how they look radiographically? |
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Definition
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Term
How do glass ionomer materials compare esthetically to composites? What do they release? |
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Definition
-Esthetics are inferior to composite materials -Release fluoride |
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Term
What are glass ionomer products used for? |
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Definition
Base/liner products and cements under crowns |
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Term
What are some things to take into account when selecting restorative materials? |
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Definition
1.Method of cure (light or chemical cured) 2.Patient’s desire for esthetics 3.Strength required by location of restoration 4.Handling characteristics |
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Term
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Definition
surface cracks formed in a glass ionomer from dehydration |
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