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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Term
| 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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Term
| 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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Term
| What usually requires heat activated acrylic resins? |
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Definition
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Term
| 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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Term
| 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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Term
| 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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Term
| 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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Term
| What are the components of dental composites? |
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Definition
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Term
| 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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