**Composite Resin Flashcards
EFDA
What is the process thorough which composite resin hardens?
polymerization
True or False: Composite restorations are held in place only by the use of chemical retention?
False
True or False: Composite has a lower rate of thermal expansion in comparison to amalgam?
True
Which dental restoration holds weakened cusps together?
Composite
True or False: The expansion and contraction rates of composite and natural tooth structure are similar.
True
Does composite cause a galvanic reaction?
No
Are larger or smaller filler particles in composite resins easier to polish?
Smaller
Can eugenol be use as a base under composite restorations?
No
Is a “butt joint” placed in conventional or modified type preparations?
conventional type
How many degrees is a bevel placed at on cavosurface margins?
45 degrees
What area of natural tooth structure does not properly support a bevel margin?
At areas of occlusion
What does the “BIS-GMA” stand for?
BIS= bisphenol A, GMA= glycidylmethacrylate
Is the BIS-GMA the organic or inorganic compound found in composite resins?
organic
What was the first type of inorganic particle fillers used in composite resins?
Macro-fill
Which composite resin’s particle size is most susceptible to extrinsic staining?
Macro-fill
Why are micro-fill composite resins difficult to view on radiographs?
Because they are radiolucent
Which has a higher percentage of inorganic filler at 75-80%?
Macro-fill or nano-fill?
Macro-fill
What is the type of filler material that is a combination of macro-fill and micro-fill particles?
Hybrid fill
What type of inorganic filler particles are developed in “clusters?”
Nano-fills
What are the filler particles treated with in composite resins to aid in providing a bond between them and the resin matrix?
Organic silane-coupling agent
What is the purpose of adding pigments into composite resin materials?
To provide color for shade matching
Which has a lower viscosity?
Flowable composite or packable composite
Flowable
Why can flowable composite not be used alone in large preparations?
Because of the lack of strength and the shrinkage rate
True or False: Packable composite has a higher shrinkage rate in comparison to flowable composite?
False
What is used for enamel conditioning?
Etch
What is used for dentin conditioning?
Bonding agents
What is the percentage of phosphoric acid in etch?
32-40%
How far onto the cavosurface margin should etch be extended onto?
1mm
What is it called when a bonding agent has the properties of being self-etching, plus has the primer and bonding agent in a single step?
Total Etch Technique
Does the tooth need to be completely dry after etch has been rinsed, and prior to applying bonding agent?
Yes
If a preparation becomes contaminated after rinsing etch and drying, you do not need to reapply etch prior to proceeding to the bonding process?
False
What should a properly etched tooth surface look like?
A frosty white appearance
What is used to remove the smear layer from a preparation?
Etch
Is bonding agent a filled or unfilled resin?
Unfilled
At what part of the process of placing a restoration are resin tags created?
When the bonding agent is cured
Are bonding agents hydrophobic or hydrophilic in nature, before the addition of primers?
hyrdophobic
What material provides the mechanical retention for composite restorations?
Etch
What material provides the chemical retention for composite restorations?
Bonding agents
How is polymerization activated in self-cure materials?
Chemically
What type of polymerization allows for a longer working time?
Light cure
True or False: Opaque shades could require a longer curing time than translucent shades?
True
What is the air-inhibited layer of a composite restoration?
a thin layer of uncured resin that remains on the surface due to the exposure to air that inhibits polymerization?
What is the material used to join resin composite to tooth structure?
Bonding agent
What can be added to composite resin to make it easier to read on a radiograph?
Filler materials can be made to be radiopaque, including barium, stronium, zinc, or zirconium
True or False: Composite fillings cannot be completed in one appointment, and patient’s need to be rescheduled to complete finishing and polishing of the restoration?
False
Can copal varnish be used under composite?
No
True or False: Complete isolation needs to be achieved for the success for a composite restoration.
True
List the inorganic fillers that can be used in the composition of composite resin.
Quartz, silica, lithium aluminum silicate, barium glasses, zirconium, ziolite
What type of inorganic filler material has 0.04 micron-sized particles?
Micro-fills
What type of inorganic filler particles are a combination of micro-fills and hybrid fills?
Micro-hybrid
What type of resin is commonly used in non-stress-bearing restorations, like Class V, or also as a base/liner?
Glass ionomer
True or False: Glass ionomer cannot bond to dentin or cementum; only to enamel?
False
What material is used to remove the smear layer?
Etch
What is the smear layer?
The residue from the cut tooth structure that is left behind after prepping and is covering the dentinal tubules, until properly removed with etch
How far away from the restoration should you hold the curing light during polymerization?
2-3mm
What is a typical measurement of an incremental layer of composite?
2-3mm
What type of shades can require longer curing times?
darker or more opaque shades
Define: air-inhibited layer
a thin outer layer of uncured resin that remains on the surface due to exposure of the outer layer to air that inhibits polymerization
How can you prevent the air-inhibited layer while curing an anterior composite restoration?
Cover the restoration with a mylar strip during polymerization
In order to remove the air-inhibited layer after polymerization, should you overfill or underfill the restoration?
overfill
What are the etching and bonding steps to be followed if a restoration has been cured and becomes contaminated, and more restorative material needs to be added back?
re-etch the area for 10-20 seconds, rinse and dry, and add a thin layer of bonding agent
For the most accurate shade selection, should the tooth be moist or dry?
moist
Of the three coronal thirds of a tooth, which area has the most translucency?
incisal third
Of the three coronal thirds of a tooth, which area is the darkest?
cervical third
Why is the cervical third of the coronal portion of the tooth darker than the incisal third?
it has thinner enamel, and the darker shade of the dentin can be seen
Can bases or liners be placed on the dentin and enamel under a composite restoration?
only the dentin; it must be removed from the enamel before proceeding to the etching step
Why do bonded restorations result in a smaller preparation than amalgam restorations?
less of a need for retentive undercuts/mechanical retention
What materials can be dispensed in the inorganic filler?
quartz, silica, lithium aluminum silicate, barium glasses, or in nanofil composites- ground particles of zirconium and zeolite
Why do the inorganic fillers enhance the physical properties of the finished composite restoration?
-increase the strength
-reduce thermal expansion
Does amalgam or composite have better compressive strength?
composite
How much is the rate of thermal expansion of composite in comparison to natural tooth structure?
3x
What can be added to composite resin to make the final restoration more radiopaque?
stronium or barium glass filler
What are the three color zones of the anatomical crown of a tooth?
cervical third, middle third, incisal/occlusal third
What percentage of enamel conditioning solution should be used?
32-40%
Define: dentinal sclerosis
a micro-structural change in dentin that occurs in response to caries or stimuli
How does sclerotic dentin appear?
dark yellow and glassy/shiny
What is the main purpose of etching dentin?
to remove the smear layer, which will improve mechanical retention from the dentin tubules to the restoration
How far onto the cavosurface should you place etch?
1mm
What is the difference in the retention techniques between composite and amalgam restorations?
Amalgam is not bonded and uses only mechanical retention; composite is bonded and uses both mechanical and chemical retention
How is polymerization activated in self-cure composite?
chemically
What is the polymerization process in dual-cure composite?
first the activator ingredient will react to a light source to begin polymerization, then a chemical reaction will occur in a time determined by the manufacturer’s instructions