__________________ are materials that are made of large, long molecules formed by chemically reacting molecular building blocks called monomers
polymers
The chemical reaction that links the monomers together to produce a polymer (macromolecule) is called __________________
polymerization
Polyethylene materials have long, linear chains that are easily recycled because they can be remelted and reprocessed. These materials are called _____________ _______________
thermoplastic polymers
______________ ___________ can be heated and molded or shaped after the polymerization reaction, similar to wax.
thermoplastic polymers
polymers with a cross-linked rather than a linear structure tend not to melt. Rather, they decompose. These materials are called _______________
thermoset polymers
Acrylic resins were first used in dentistry for _______________
denture bases
Why are acrylic resins not used as a dental restorative material today?
they are very susceptible to decay
Name the three steps in addition polymerization
1. Initiation
2. Propagation
3. Termination
the growth or lengthening of the chain is called _______________
propagation
when two free radicals at the ends of two growing chains react and form a carbon-carbon bond - no free radicals are left to continue growth of the chain - this is called _______________
termination
heat activated acrylic resins typically use _______________ as the initiator. __________ is the activator
Benzoyl Peroxide (BPO)
Heat
heat activated acrylic resins come from the manufacturer as a _______________ system
powder/liquid
most complete and partial dentures use heat-activated acrylic resins for the _______________
denture base
chemically activated acrylic resins and composite materials commonly use _______________ as the initiator. _______________ are used as the activator
BPO
a variety of chemicals
chemically activated materials are typically a _______________ that are mixed together to start the polymerization process
powder and liquid
chemically activated acrylic resins are used to make ______
temporary crowns
custom impression trays
orthodontic retainers
etc
light activated dental materials use __________ activators and ______ initiator chemicals
...
one problem with polymers is their high coefficient of thermal expansion. These coefficients can be ___to___times greater than that of tooth structure.
2 to 10
Which component of restorative resins acts as a "coating" and serves to transfer stress from a weak component to a stronger one?
silane coupling agent
What advantage do microfilled composities have compared to macrofilled composites?
A. low coefficient of thermal expansion
B. Smooth and lustrous polished surface
C. Greater overall strength
D. Higher percentage of filler
B. Smooth and lustrous polished surface
Which of the following characteristics best describes chemical-cure composite restorative materials?
(a) Unlimited working time
(b) Supplied as single paste materials
(c) May incorporate air bubbles during mixing
(d) Contains less matrix and more filler p
(c) May incorporate air bubbles during mixing
A specific amount of composite (thickness) that is cured by a light source is termed:
(a) Depth of cure
(b) Incremental addition
(c) Depth of addition
(d) Incremental polymerization
(a) Depth of cure
The size of the filler particles in a dental composite determines the:
(a) Polymerization reaction
(b) Technique for incremental additions
(c) Etching time before the primer and adhesive are placed
(d) Surface smoothness of the resulting restoration
(d) Surface smoothness of the resulting restoration
The _________ composite restorative materials are those with a lower viscosity (decreased filler) to aid in placement.
(a) Preventive resin
(b) Hybrid
(c) Flowable
(d) Condensable
(c) Flowable
Hybrid composites are recommended for:
(a) Surface luster
(b) Areas needing strength
(c) Low-stress areas
(d) Class V restorations
(b) Areas needing strength
A combination of a pit and fissure sealant and a composite restoration is termed:
(a) Flowable composite
(b) Condensable composite
(c) Compomer
(d) Preventive resin restoration
(d) Preventive resin restoration
Abrasion resistance for hybrid composite restorative material is said to be:
(a) Poor
(b) Fair
(c) Good
(d) Very good
(d) Very good
Thermal expansion for microfill composite restorative material is considered to be:
(a) Poor
(b) Fair
(c) Good
(d) Very good.
(a) Poor
Which composite material has the largest percentage of filler by weight?
(a) Microfill
(b) Hybrid
(c) Macrofill
(d) Flowable
(b) Hybrid
Composite materials that polymerize using light activation are:
(a) Initiated by mixing
(b) Not as popular as chemically activated resins
(c) Supplied as a single paste
(d) Lack the "set on demand" characteristic
(c) Supplied as a single paste
A restorative material that initially releases some fluoride-like glass ionomers but bonds and sets like composites is called:
(a) Flowable composites
(b) Condensable composite
(c) Compomer
(d) Preventive resin restoration
(c) Compomer
Which of the following best describes microfill composite materials?
(a) Abrasion resistance is poor; filler size is 10-25 microns
(b) Abrasion resistance is poor; strength is high
(c) Polishability is poor; strength is high
(d) Polishability is very good
(d) Polishability is very good; strength is low
__________ are materials that are made of large, long molecules formed by chemically reacting molecular building blocks called monomers.
polymers
the chemical reaction that links monomers together to produce a polymer is called ______________
polymerization
___________________ polymers can be heated and molded or shaped after the polymerization reaction, similar to wax.
thermoplastic
polymers with a cross-linked rather than a linear structure tend not to melt. rather, they decompose - these materials are called ____________ polymers
thermoset
Most dental resins are cross-linked and are therefore _________________
thermoset
acrylic resins were first used in dentistry for _______________
denture bases
dental acrylic resin is the same polymer used in _____________, a tough plastic that serves as a glass substitute in windows
plexiglass
Acrylic resins were once used for anterior restorations but were very susceptible to __________
recurrent decay
Acrylic resins and composite materials, such as restorative materials, cements, sealants, and adhesives, all set by _________________
addition polymerization
__________ are molecules with a reactive group that participates in the polymerization reaction. This reactive group is called the ____________ group
monomers
functional
The chemical (polymerization) rxn of acrylic resins is called ____________ or addition polymerization.
free radical
3 steps of addition polymerization
1. Initiation
2. Propagation
3. Termination
name the two steps that happen in the initiation step of addition polymerization
1. formation of free radicals
2. reaction of free radical and monomer
____________ involves adding the second, third, fourth, and later monomers to the growing chain until that chain in hundreds or even thousands of monomers long
propagation
the step of addition polymerization which is responsible for the growth or lengthening of the chain is called ____________
propagation
________ happens when two free radicals at the ends of two growing chains react and form a C-C bond.
termination
________________ activated and __________ activated acrylic resins typically use benzoyl peroxide (BPO) as the initiator.
Heat activated
Chemically activated
heat activated acrylic resins come from the manufacturer as a ____________ system
powder/liquid
most complete and partial dentures use __________ activated acrylic resins for the denture base
heat
chemically activated materials are typically a _________ and a ______ that are mixed together to start the polymerization process.
powder and liquid
____________ activated acrylic resins are used to make temporary crowns, custom impression trays, ortho retainers, and may other dental devices
chemically
light activated materials are supplied as ___________
a single paste
several dental materials have both chemical and light-activated capabilities, these materials are called __________ materials
dual cure
addition polymerization is an exo or endo thermic rxn?
exothermic
Polymeric materials have (HIGH/LOW) coefficients of thermal expansion compared to tooth structure
high
Who developed the first dental composite?
Dr. Raphael Bowen
______________ are molecules that react with the polymer matrix at one end and with the ceramic filler at the other end
silane coupling agents
dental composites use _________ coated with silane coupling agents
ceramic filler particles
Dr. Bowen developed a polymer for dental composites called an _________
oligomer
Dr. Bowens oligomer is called _______
bis-GMA
Dental composites are composed of two phases: _________ and __________
matrix and filler
the ___________ of a dental composite is a polymer, typically bis-GMA or a similar monomer.
matrix
the __________ is the phase that polymerizes to form a solid mass and bonds to tooth structure.
matrix
shortcomings of composite matrix
- weakest
- least wear-resistant
- absorbs water
- can stain and discolor
what is used as a filler in dental composites?
engineered glass
the _____________ enables adhesive materials to bond ceramic restorations to tooth structure
silane coupling agent
what is the purpose of silane coupling agents?
adds strength to the filler
two polymerization systems are used to convert the matrix-filler paste to a solid composite material:
1. chemically activated materials
2. light activated materials
the first type of dental composite to be developed in the 1960s is now called a ____________
macrofilled composite
the (LARGE/SMALL) size of the filler particles in MACROfilled composites results in a restoration that feels rough to the dental explorer and can appear rough to the eye.
large
typically, (MACRO/MICRO) filled composite will turn slightly gray when rubbed with an instrument
MACROfilled
the problem with MICROfilled composites is the ___________
low % of filler
the high resin content in MICROfilled composites results in an (INCREASED/DECREASED) coefficient of thermal expansion and (HIGHER/LOWER) strength
increased
lower
glass ionomer materials release _________ over time.
fluoride