Chapter 6 Flashcards
Definition of direct-placement esthetic materials
tooth-colored materials that can be placed directly into the cavity preparation without being constructed outside of the mouth first
Definition of composite resin
tooth-colored material composed of an organic resin matrix and inorganic filler particles
Definition of organic resin (polymer) matrix
thick liquids made up of two or more organic molecules that form a matrix around filler particles
Definition of silane coupling agent
chemical that helps bind the filler particles to the organic matrix
Definition of pigments
coloring agents that give composites their color
Definition of self-cured composite
composite that polymerizes by a chemical reaction when two resins are mixed together
Definition of light-cured composite
composite that polymerizes when a chemical is activated by light in the blue wave range
Definition of dual-cured composite
composite that contains components of light-cured and self-cured composites. when the two parts are mixed together, it polymerizes by a chemical reaction that can be accelerated by blue light activation
Definition of macro filled composite
an early generation of composite that contained filler particles ranging from 10 to 100 micrometers
Definition of microfilled composite
composite that contains very small filler particles averaging on 0.04 micrometers in diameter
Definition of hybrid composite
composite that contains both macro fill and microfilm particles to obtain the strength of a macro fill and the polish ability of a microfill
Definition of flowable composite
light-cured, low-viscosity composite resin that contains fewer filler particles
Definition of packable composite
light-cured, highly viscous, heavily filled composite resin for dentists who use a placement technique with composite that is similar to that of amalgam
Definition of glass ionomer cements
self-cured, tooth-colored, fluoride-releasing restorative material that bonds to tooth structure without an additional bonding agent
Definition of hybrid (resin-modified) glass ionomer
glass ionomer to which resin has been added to improve its physical properties
Definition of compomer
composite resin that has polyacid, fluoride-releasing groups added
Definition of indirect-placement esthetic materials
tooth-colored materials that are used to construct restorations outside of the mouth in the dental laboratory or at chair side on replicas of the prepared teeth
What are the 4 most common direct placement materials?
composite resin
glass ionomer cement
resin modified glass ionomer cement (hybrid)
compomer
What are composites mainly composed of?
organic resin (polymer matrix)
inorganic silica
filler particles joined by a silane coupling agent
What is the material that the organic resin matrix and inorganic filler particles joined by?
silane coupling agent that sticks (adheres) the particles to the matrix
What is the most commonly used resin for the matrix of composites?
biz-gamma (GMA)
How is biz-gamma produced?
by reacting glycidyl methacrylate with bis-phenol
What is another resin that is used for composite matrix?
urethane dimethacrylate (UDMA)
What is the low molecular weight monomer added to reduce viscosity?
teg-DMA
What is a monomer?
molecules with double-carbon bonds that link together to form resin/polymer
What filler particles are added to make composites more radiopaque?
ions of: barium boron zirconium yttrium
What is the crystalline form of silica?
quartz
What is the non-crystalline form of silica?
glass
True or False
Larger filler particles tend to get pulled (called plucking) from the resin matrix at the surface when the restoration is under function or abraided
True
True or False
Smaller particles cause fewer voids that contribute to wear
True (because they are not as easily plucked)
What is a base?
benzoperoxide
What is a catalyst?
tertiary amine
What is polymerization?
low weight resin molecules called monomers that join together to form long chains with high molecular molecules called polymers
What is a self-cured composite?
two-paste stem that contains composite and benzoperoxide as initiator, the other paste is the catalyst containing a tertiary amine
True or False
Air can be incorporated into materials when mixing that causes voids or porosity in the restoration
True
What is the wavelength of blue light?
470 nm
What is the name of the initiator?
camphoroquinone
What does camphoroquinone in the presence of an accelerator?
causes resin to polymerize
In how many mm increments should composite be placed?
no more than 2
True or False
Darker shades require a longer curing time
true (because light is more readily absorbed by the dark color and does not transmit through the material)
What was the first generation of composite resins called?
macro-filled composites that contain large particles as fillers ranging in size from 10 - 100 microns
What is the filler particle size in micro-filled composites?
0.04 micrometers in diameter and range in size from 0.03 - 0.05
What does a hybrid composite consist of?
macro and micro molecules
What is the filler content of a hybrid composite?
70 - 80%
What is the filler particle size of a hybrid?
0.1 - 3 micro meters
What is the filler content in micro-filled composites?
35 - 50%
What is the percentage of a lightly filled flowable composite?
40%
What is the percentage of a highly filled flowable composite?
70%
What are smart composites?
composites that release fluoride, calcium, and hydroxyl ions when the acidity around the restoration increases
True or False
Provisional composites are preferred over acrylic because they shrink less, wear less, and release less heat
True
True or False
The greater the resin content of the composite, the greater the shrinkage
True
True or False
The greater the filler content, the lower the coefficient of thermal expansion
True
True or False
The higher the resin content, the greater the coefficient of thermal expansion
True
True or False
The greater the volume of the filler, the stiffer and more wear resistant is the restoration
True
True or False
The elastic modulus (stiffness of the composite) is determined by the amount of filler
True
True or False
The greater the resin content, the more water is absorbed
True
True or False
Micro-fills and flowables tend to have greater water sorption
True
What is hydrolysis?
water that has softened the resin matrix leading to gradual degredation
True or False
Water causes some hydroscopic expansion of the composite over the first week after placement?
True
True or False
For class III and IV anterior restorations, a clear matrix strip is used
True
What is the hybrid zone/layer?
resin rich layer/resin infiltrated dentin
True or False
The completed restoration compromises a series of layers of resin-based materials that are all chemically bonded to each other and micro mechanically bonded to the tooth structure
True
True or False
Eugenol inhibits the set of resins
True
What are the typical curing times for halogen lights for thin layers?
20 - 40 seconds
True or False
Halogen is actually quartz-tungsten
True
What are the four types of curing lights?
halogen
plasma
laser
LED
What is the output of a halogen light?
400 - 800 megawatt/cm^2
What is the downside of using plasma and laser lights to cure materials?
although they cure the material faster (10 seconds), they increase the heat transmitted to the composite
What is the most popular curing light?
diode because it can last 5,000 hours
True or False
The curing light generates a certain amount of heat as it is applied to the tooth and composite resins release heat when they polymerize
True (exothermic)
True or False
An increase in pulpal temperature of about 6 degrees has the potential to cause death or inflammation of the pulp
True
True or False
Glass ionomers release fluoride
True (it is very high in the first few days then tapers to low levels)
True or False
Glass ionomers can absorb fluoride and then re-release it
True (they can act as a fluoride reservoir)
True or False
Glass ionomers are highly susceptible to moisture intake the first 24 hours
True
True or False
Saliva is a super saturated solution of calcium and phosphate ions, and contain fluoride
True
True or False
Hybrid composites have high compressive and flexural strength
True
What type of acid is used to bond composites?
phosphoric acid
True or False
Glass ionomer cement (GIC) is not very viscous
True
What is a compomer?
composite resin that has been modified with poly-acid
For a composite to have greater wear resistance, it needs..
to have a higher filler content
Composite resins are often classified according to their…
filler particle size
The shortcomings of flowable composites as compared with hybrid composites include all of the following EXCEPT. Which one is this EXCEPTION?
they are more difficult to polish
The purpose of a silane coupling agent for composite resins is
improve the bond between the filler particles and the resin matrix
The curing light requires repair
if a 2-mm-thick piece of composite does not cure through the bottom at the recommended exposure time
The polymerization shrinkage of a composite
can be minimized by placing and curing a series of small increments
True or False
All composite restorative materials appear the same on radiographs of the teeth
False
One of the advantages of glass ionomer is
that it has been shown to release fluoride
Hybrid (resin-modified) glass ionomers have all of the following advantages over conventional glass ionomers EXCEPT one. Which one is the EXCEPTION?
contain quartz fillers like some composites
Compomer restorative materials
are closer to composite resins in their makeup than to glass ionomers
