Dental Materials Lecture 8

what are the four major components of dental resin composites

organic polymer matrix, inorganic filler particles, coupling agent, initiator-accelerator system

what are the 3 types of activation possible in dental resin composites

chemical, light/heat, dual

"cross-linked resin network formed primarily from dimethacrylate monomers" is indicative of what major component of dental resin composites

organic polymer matrix

"glass, quartz, silica, ceramics, or nanoparticles reinforce the resin" is indicative of what major component of dental resin composites

inorganic fillers

"silane chemically links the inorganic fillers to the organic matrix" is indicative of what major component of dental resin composites

coupling agent

"starts polymerization and hardening through light, chemical, or dual curing" is indicative of what major component of dental resin composites

initiator-accelerator

Bis-GMA falls under what major component of dental resin composites

organic polymer matrix

UDMA falls under what major component of dental resin composites

organic polymer matrix

TEGDMA falls under what major component of dental resin composites

organic polymer matrix

Bis-EMA falls under what major component of dental resin composites

organic polymer matrix

BisGMA is a combination of what 2 types of resin

epoxy and acrylic

diluent monomers are necessary because high-viscosity base monomer are ______________________ after fillers are incorporated

difficult to handle

is Bis-GMA viscous or runny

viscous

adding inorganic fillers to Bis-GMA further limits _______ and _____________

flow, handling

to lower the viscosity of Bis-GMA, what are the 2 lower molecular weight difunctional monomers you can add

TEGDMA and Bis-EMA

the clinical outcome of adding TEGDMA or Bis-EMA to Bis-GMA would be more controlled ____________ and _____________ composite consistency

viscosity, workable

"Bisphenol A-glycidyl methacrylate" is what monomer type

Bis-GMA

"Urethane dimethacrylate" is what monomer type

UDMA

"Triethylene glycol dimethacrylate" is what monomer type

TEGDMA

"Siloxane-oxirane hybrid monomer" is what monomer type

silorane

Key function and role: "primarily structural monomer; high molecular weight" is what monomer type

Bis-GMA

Key function and role: "alternative high-MW monomer; flexible backbone" is what monomer type

UDMA

Key function and role: "viscosity control diluent added to monomer mix" is what monomer type

TEGDMA

Key function and role: "cationic ring-opening polymer system" is what monomer type

silorane

Properties and characteristics: "high viscosity due to hydrogen bonding; matched refractive index to glass" is what monomer type

Bis-GMA

Properties and characteristics: "lower viscosity than Bis-GMA; tough cross-linked polymer network" is what monomer type

UDMA

Properties and characteristics: "low MW, high double bond reactivity; increases polymerization shrinkage" is what monomer type

TEGDMA

Properties and characteristics: "substantially lowers shrinkage and stress; hydrophobic siloxane matrix" is what monomer type

silorane

"Finely ground quartz or glass ; sol-gel ceramics ; microfine silica ; nanoparticles" is indicative of what

inorganic filler phase

"Hydrolyzable groups bond to filler surfaces ; methacrylate groups copolymerize with resin" is indicative of what

silane interface

"light-cured, chemically-cured, or dual-cured systems form the hardened network" is indicative of what

curing mechanisms

beyond conventional methacrylates; some low-shrinkage systems use cationaically polymerized ___________ groups or alternative ____________ technologies

oxirane, resin/filler

a filler size of 20-30 µm is

macrofill

a filler size of 0.04-0.2 µm is

microfill

a filler size of 0.04-0.2µm and 2-4 µm is

hybrid (multipurpose)

a filler size of 0.04-0.2 µm and 0.04-1 µm is

microhybrid

a filler size of 1-100 nm is

nanofill

a filler size of 1-100 nm and 0.4-5 µm is

nanohybrid

the amount of filler (dispersed phase) present is generally _______% (what range) by volume

30-70

the amount of filler (dispersed phase) present is generally _______% (what range) by weight

50-85

filler (dispersed phase) reduces or increases polymerization shrinkage?

reduces

the 24 hr shrinkage range of polymerization shrinkage in filler (dispersed phase) is ______ vol% (what range?)

1.5-4

if the filler (dispersed phase) is bonded to the matrix, this (improves/reduces) physical properties

improves

can fillers provide radiopacity?

yes

what is an example of a filler that provides radiopacity

barium

the amount of filler added is limited by what 2 things?

viscosity and packing factor of the filler

what is the theoretical maximum of the packing of the filler (what vol%)

74

the filler silicon oxide (SiO2) is _____ to ______ micrometers

0.04, 0.06

the filler "ground quartz or glasses" are _______ to ______ micrometers

0.1, 100

the filler quartz are "strong and hard" or "weak and soft"

strong and hard

what is the refractive index of the filler quartz

1.5

are quartz chemically stable?

yes

the filler quartz are (radiolucent/radiopaque)

radiolucent

Ba, Zr, Sr glasses are (harder/softer) than quartz

softer

Ba, Zr, Sr glasses are (easier/harder) to grind and polish than quartz

easier

the refractive index is Ba, Zr, Sr glasses is

1.5

Ba, Zr, Sr glasses are chemically (less/more) stable than other fillers

less

Ba, Zr, Sr glasses are (radiolucent/radiopaque)

radiopaqur

___________ (what element) is a very commonly used glass filler

barium

can fibers be fillers (i.e. nylon or similar polymers)

yes

with fillers, uniform size and shape of filler (increases/decreases) filler amount

decreases

with fillers, uniform size and shape of filler (increases/decreases) the matrix amount

increases

smaller particle sizes in fillers allows for __________ packing of the filler

closer

silica has a surface area of up to _______ m^2/g

300

silica very (rapidly/slowly) increases viscosity

rapidly

production and manipulations of material and structures within 0.1 and 100 nm scale obtained by chemical or physical methods

nanotechnology

silane treated nanoclusters are the result of __________ and __________ clustering together artificially

zirconium, nanometer sized silica

if you reduce particle size, it results in the reduction of what 2 things

surface area and volume

reducing the volume and increasing the number of particles results in a (increase/decrease) in the contact area with the organic matrix

increase

reducing the volume and increasing the number of particles results in a increase in the contact area with the organic matrix, thus increasing the _______________ of restorations

wear resistance

in resin composites, maintenance of shiness/gloss and retention of polish is linked to the material's...

resistance

before the use of _______________, restorations stained and lost their shine and polish

nanotechnology

adhesives with fillers can provide a (more/less) uniform polymerized film

more

adhesives with fillers can provide a more uniform polymerized film, resulting in greater and more homogenous (constant) _________________ compared to dentin

bond strength

using adhesives with fillers results in more ____________ restorations

durable

with filler-matrix bonding agents, stress transfer between _________ must occur

phases

bifunctional monomer which can react with the silicate portion of the filler particles and the chain polymer of the matrix

coupling agent

filler-matrix bonding agents have (high/poor) interaction with most fibers

poor

another additive that prevents spontaneous polymerization are known as

inhibitors

inhibitors are very important in _________ activated materials

light

another additive to matrix are _________ modifiers

optical

optical modifiers may affect ________ polymerization

light

in optical modifiers, metal oxides act as

colorants

in optical modifiers, titanium and aluminum act as

opacifiers

Class 1 of polymer-based fillings and restorative materials is ____________ activation

chemical

Class 2 of polymer-based fillings and restorative materials is ____________ activation

light/heat

Class 3 of polymer-based fillings and restorative materials is ____________ activation

dual

one of the clinical decisions to achieve our goals is to preserve the maximum amount of sound

tooth structure

one of the clinical decisions to achieve our goals is to restore what 3 things

form, function, esthetics

one of the clinical decision to achieve our goals is to delay more ____________ treatment

extensive

bulk fill composites overcome shortcomings of what

layering

bulk fill composites are a modified basic composition (similar/different) compared to other direct restorative composites

similar

T/F: bulk fill composites can have both very high and low viscosity

T

bulk fill composites are designed to be placed in larger increments of _______ mm (what range) with a single light exposure

4-5

the first materials classified as bulk fill composites were designed as flowable and had (higher/lower) mechanical properties

lower

the first materials classified as bulk fill composites were designed as flowable and needed a ____________ layer of a posterior restoration

capping

with bulk fill composites, development to enhance the depth of cure included matching the ____________ index of the filler to that of the matrix resin

refractive

with bulk fill composites, development to enhance the depth of cure included reducing light scattering within the composite by incorporating

larger-size filler particles

T/F: with bulk fill composites, development to enhance the depth of cure included using new monomers

T

with flowable resin composites, they contain a (greater/lesser) amount of the typical glass filler particles

lesser