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103 Cards in this Set

  • Front
  • Back
Which of these is considered metallic?

Al (the rest are nonmetallic)
A ceramic is a compound of what two types of elements?
a metal and nonmetal
a glass-ceramic is a glassy matrix containing one or more ___ phases
glass-ceramic is produced by a process called CERAMMING; describe this process.
controlled nucleation and growth of crystals in glass
What is the term for a dental ceramic that provides a strong base onto which a body ceramic is veneered?
core ceramic
Give 3 examples of a core ceramic
lithium disilicate, alumina, spinel
An alumina core contains what for strength?
Spinel or spinelle contants what as a core?
Dicor is an example of what?
a castable ceramic

(extra info from class, not in the notes)
Other than dicor, what is an example of castable ceramic?
fluoride mica silicate
A dental ceramic that is speciallfy formulated to be cast using the lost-wax technique is called what?
castable ceramic
A process using heat and pressure to mold molten ceramic into a predetermined shape is known as what?
heat pressing
A process using a ceramic slurry (slip) sintered on a porous plaster die to form the core, followed by glass infiltration of core is called what?
The following describes slip-casting:

A process using a ceramic slurry (slip) sintered on a porous plaster die to form the ___, followed by ___ infiltration of core is called what?
core, glass
There are 10 ways to classify ceramic materials, what are these 10 and which is the most common classification?
* = most common

processing method*
substrate material
firing temperature
fracture resistance
What are the ways to classify a ceramic according to type?
feldspar porcelain
leucite-reinforced porcelain
What are the ways to classify a ceramic according to processing method?
What are the ways to classify a ceramic according to use?
denture teeth
post & cores
What are the ways to classify a ceramic according to substructure material?
ceramic core
Which of the 10 classification methods is typically used to classify PORCELAIN?
firing temperature
What are the ways to classify a ceramic according to composition?
leucite-based glass ceramic
glass-infiltrated alumina
glass-infiltrated zirconia
glass-infiltrated lithia ceramics
What are the ways to classify a ceramic according to firing temperature?
What are the ways to classify a ceramic according to microstructure?
glass w/crystalline phase
What are the ways to classify a ceramic according to translucency?
Which of these is a way that Alumina can NOT be processed?

Stress is focused at the (tips/interiors) of surface flaws
Stress buildup leads to crack initiation and propagation through (brittle/ductile) materials
Why does failure occur when stresses are applied?
Because the localized STRESS CONCENTRATION increases past theoretical strength at low avg. stress
Brittle materials are (either strong or weak)

___ in tension
___ in compression
weak, strong
True or False, in tension, brittle materials fail because tensile forces pull cracks open, causing them to propagate through the material
True or False, with a brittle material, compressive forces cause cracks to propagate quickly
False (slowly)
True or False, compressive forces tend to hold cracks and surface flaws closed, making it more difficult for them to propagate in brittle materials
What are three ways to strengthen brittle materials?
-surface smoothing
-introduction of residual surface compressive stresses
-interruption of crack propagation
True or False, brittle materials can be permanently strengthened by removing surface flaws
False (temporary only)
What are the two simplest and cost effective methods of removing surface flaws (to help strengthen ceramic)?
When trying to strengthen brittle material by introducing residual surface compressive stresses, the body of the material us under (tensile/compressive) stress
What products are strengthened by the introduction of residual surface compressive stresses?
tempered glass
pre-stressed concrete
Corelle dishes
What are the three main ways to introduce residual surface compressive stresses?
ion exchange
thermal tempering
thermal expansion mismatch
Ion exchange is on method of introducing surface compressive stresses and is typically accomplished by placing a glass article containing ____ in a bath of molten ___ nitrate
sodium, potassium
Which is larger, Na or K?
K is 36% larger
How does the introduction of K for Na in glass add to the strength of the glass?
K must squeeze into areas where Na was and since K is bigger, it exerts stress on the surrounding glass and create compressive stress in the surface layer.
GC's Tuf-Coat is a product that uses __ to strengthen the product
ion exchange
__ __ is used to strengthen automobile windows, plate glass windows, diving masks, etc.
thermal tempering
Thermal tempering works by freezing the (inner/outer) skin of molton glass by jets of (water/air)
outer, air
in thermal tempering, as the core solidifies, it (pushed/pulls) the outer layer creating residual compressive stress
Corning's Corelle for making plates and bowls is strengthened by which technique?
thermal expansion mismatch
Thermal expansion mismatch is done by having an inner layer of (higher/lower) thermal expansion glass between two layers of (higher/lower) thermal expansion glass
higher, lower
In MCRs, thermal expansion mismatch is used such that the metal has a (higher/lower) thermal expansion so it contracts more than the porcelain putting the porcelain in residual compression
Strengthening brittle materials be reinforcing them with a dispersed crystalline phase that hinders or interrupts the travel of a crack through a material is called what?
interruption of crack propagation
what are the three different types of dispersions in the interruption of crack propagation?
tough crystallin phase (dicor, aluminous porcelains for PJCs)

particle-matrix thermal expansion coefficient mismatch (MCR porcelains, optec, IPS empress)

transformation toughening (strengthening ZrO2 w/disperset YtO (Y-TZP), Ce or Al to absorb energy at crack tip)
True or False, the design of all-ceramic restorations requires familiarity with intrinsic properties of the ceramic used and with principles of fixed partial denture technique
Tooth reduction for ceramic restorations should be __ to __ axially and __ to __ occlusally. Why?
to allow for adequate thickness for strength
Sudden changes in shape and thickness of a ceramic restoration are (more/less) likely to cause stress razors
Areas of inadequate reduction and (dull/sharp) internal line angles are most common places for failure of ceramic restorations
Dicor and Dicor MGC are examples of which of the following?

castable glass-ceramics
heat-pressed ceramics
slip-cast ceramics
chairside CAD/CAM
lab based CAD/CAM
IPS empress classic and IPS empress 2 are examples of which of the following?

castable glass-ceramics
heat-pressed ceramics
slip-cast ceramics
chairside CAD/CAM
lab based CAD/CAM
In-ceram alumina, spinel, zirconia are examples of which of the following?

castable glass-ceramics
heat-pressed ceramics
slip-cast ceramics
chairside CAD/CAM
lab based CAD/CAM
Cerec 3, E4D are examples of which of the following?

castable glass-ceramics
heat-pressed ceramics
slip-cast ceramics
chairside CAD/CAM
lab based CAD/CAM
procera, cercon, lava are examples of which of the following?

castable glass-ceramics
heat-pressed ceramics
slip-cast ceramics
chairside CAD/CAM
lab based CAD/CAM
lab based
for an aluminous porcelain (jacket) crown, __ oxide coatings electroplated on __ foil form a bond with feldspathic porcelain resulting in a restoration with reduced subsurface porosity and fewer microcracks
Tin, Pt
aluminous porcelain (jacket) crowns have a better "survival rate" on anteriors than posterior, T or F?
Alumina core crowns are made of __-__% alumina with an outer later of (translucent/opaque) porcelain
40-50, translucent
alumina core crowns have twice the flexural strength of feldspar and (higher/lower) failure in posterior crowns than anterior
For magnesia core crowns, a (low/high) expansion magnesium oxide core is covered by body and incisal feldspathic porcelain, but weren't widely used because they require the __ foil technique
high, Pt
Castable and machinable glass-ceramics like Dicor and Dicor MGC case using __-bonded investment material and lost-wax technique, __blasing, covered by embedment material, (water/heat) treated to grow crystalline mica (known as ___) and then coated with veneering porcelain; (very/not very) abrasive
phosphate, sand, heat, ceramming, very
True or False, Dicor is no longer sold
Which has higher flexural strength between these two heat-pressed ceramics?

IPS empress classic
IPS empress 2
IPS empress 2 (350-400MPa) whereas IPS empress classic is only 125 MPa

1. IPS empress classic
2. IPS empress 2

A. high leucite-content porcelain
B. lithium disilicate
1A, 2B
For heat-pressed ceramics, the ceramic is heated to __C and then pressure injected into investment material molds of the type used in the lost wax technique
Why is empress 2 heat treated?
increase flexural strength
The initial cost for equipment in heat-pressed ceramics is (high/low) and results in good fit and high strength
What are the three forms of In-Ceram slip-cast ceramics available?
The follow describes which technique?

A ceramic slurry is sintered on a porous plaster die to form a porous net-shape coping, which is then infused with low-viscosity glass
Slip-cast ceramics (the slurry is also known as slip)
Alumina has a flexural strength of __MPa but (can/cannot) be etched and silane-treated
400, cannot
Spinel has a flexural strength of ___MPa and is (more/less) translucent than Alumina
375, more
For slip-casting, as the material's flexural strength goes up, the optical properties (decrease/increase)
Zirconia has a flexural strength of __MPa and is more (translucent/opaque) than alumina
600-700, opaque
What does CAD/CAM stand for?
computer-aided design, computer-aided machining
True or False, a CAD/CAM machine allows the dentist to complete posterior crowns, inlays, onlays and veneers in 1 appointment
True or False, CAD/CAM restorations cannot be stained or glazed
False, they can
True or False, no extra training is required to use a CAD/CAM because they're easier than pie.
Machines in CAD/CAMs have to account for the __-__% shrinkage of aluminum oxide core
For Porcera AllCeram, densly sintered alumina core is pressed to the new dimensions and machine, and then veneered with special (high/low) fusing porcelain
Procera AllCeram is used for ___ on anterior and posterior teeth only
For Cercon, a strong __-stabalized zirconia framework is milled and then veneered with sintered (translucent/opaque) feldspathic porcelain
YtO, translucent
The following pertains to Cercon:

Zirconia framework undergoes transformation (weakening/toughening) in vicinity of a crack from high-temp metastable form to room-temp ___ form, resulting in a volumetric (contraction/expansion) and residual compressive stress
toughening, equilibrium, expansion
The flexural strength of Cercon is __ MPa
What machining product is the strongest with CAD/CAM technology?
The following pertains to Lava:

A ___ core that is machined in Lava Design System

For crowns, FPDs for (anteriors/posteriors), custom implant abutments, inlays, onlays

(Should/should not) be etched with HF, use conventional cements

Improved (translucency/opacity), marginal fit and strength

Flexural strength of ___MPa
Y-TZP, anteriors, should not, translucency, 900-1200
Partially-sintered Y-TZP blanks that are final-sintered after machining permit faster, (higher/lower) temp milling and healing of millin-induced defects during final-sintering
Fully-sintered Y-TZP blanks require (high/low) temp milling and may produce microcracks and near-surface damage that shorten the lifespan of the blanks
The following are properties of dental ceramics:

chemically stable
thermal conductivity and coefficient of thermal expansion (higher/similar/lower) than enamel and dentin
(ductile/brittle) behavior
abrasive nature
(low/high) fracture toughness and tensile strength
correlation of glass content with ___ and mechanical properties
similar, brittle, low, optical
What is the most important property other than flexural strength?
fracture toughness
Random distribution of small defects (porosities, microcracks) in brittle materials that can cause strength variations is related to what?
fracture toughness
True or False, strength values are of limited use in designing restorations made of brittle materials
Fracture toughness is measured by the resistance of brittle materials to ___ propagation of flaws under applied stress
What is measured using Critical Stress Intensity?
fracture toughness
Kic is the abbreviation for what?

(the i and c are subscripts)
critical stress intensity, a measure of fracture toughness
What are the units of measure for critical stress intensity?
MPa x m^(1/2)
What is the main specimen type used to test fracture toughness?
single-edge notch specimen
In general, translucency (increases/decreases) as strength increases
What in saliva can cause crack growth and stress corrosion in glass containing ceramics resulting in decomposition of their glass structure?