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103 Cards in this Set
- Front
- Back
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Which of these is considered metallic?
Al Si F B O |
Al (the rest are nonmetallic)
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A ceramic is a compound of what two types of elements?
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a metal and nonmetal
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a glass-ceramic is a glassy matrix containing one or more ___ phases
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crystalline
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glass-ceramic is produced by a process called CERAMMING; describe this process.
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controlled nucleation and growth of crystals in glass
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What is the term for a dental ceramic that provides a strong base onto which a body ceramic is veneered?
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core ceramic
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Give 3 examples of a core ceramic
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lithium disilicate, alumina, spinel
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An alumina core contains what for strength?
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Al2O3
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Spinel or spinelle contants what as a core?
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MgAl2O4
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Dicor is an example of what?
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a castable ceramic
(extra info from class, not in the notes) |
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Other than dicor, what is an example of castable ceramic?
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fluoride mica silicate
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A dental ceramic that is speciallfy formulated to be cast using the lost-wax technique is called what?
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castable ceramic
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A process using heat and pressure to mold molten ceramic into a predetermined shape is known as what?
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heat pressing
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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?
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slip-casting
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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
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There are 10 ways to classify ceramic materials, what are these 10 and which is the most common classification?
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* = most common
type processing method* use substrate material composition firing temperature microstructure translucency fracture resistance abrasiveness |
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What are the ways to classify a ceramic according to type?
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feldspar porcelain
leucite-reinforced porcelain glass-ceramic all-ceramic |
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What are the ways to classify a ceramic according to processing method?
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sintering
machining copy-milling slip-casting heat-pressing CAD-CAM |
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What are the ways to classify a ceramic according to use?
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crowns
FPDs inlays onlays veneers denture teeth post & cores anterior posterior |
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What are the ways to classify a ceramic according to substructure material?
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cast
glass-ceramic CAD-CAM ceramic core |
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Which of the 10 classification methods is typically used to classify PORCELAIN?
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firing temperature
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What are the ways to classify a ceramic according to composition?
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leucite-based glass ceramic
glass-infiltrated alumina glass-infiltrated zirconia glass-infiltrated lithia ceramics |
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What are the ways to classify a ceramic according to firing temperature?
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low-fusing
medium-fusing high-fusing |
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What are the ways to classify a ceramic according to microstructure?
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glass
crystalline glass w/crystalline phase |
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What are the ways to classify a ceramic according to translucency?
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opaque
translucent transparent |
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Which of these is a way that Alumina can NOT be processed?
machined heat-pressed sintered slip-cast |
heat-pressed
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Stress is focused at the (tips/interiors) of surface flaws
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tips
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Stress buildup leads to crack initiation and propagation through (brittle/ductile) materials
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brittle
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Why does failure occur when stresses are applied?
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Because the localized STRESS CONCENTRATION increases past theoretical strength at low avg. stress
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Brittle materials are (either strong or weak)
___ in tension ___ in compression |
weak, strong
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True or False, in tension, brittle materials fail because tensile forces pull cracks open, causing them to propagate through the material
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True
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True or False, with a brittle material, compressive forces cause cracks to propagate quickly
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False (slowly)
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True or False, compressive forces tend to hold cracks and surface flaws closed, making it more difficult for them to propagate in brittle materials
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True
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What are three ways to strengthen brittle materials?
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-surface smoothing
-introduction of residual surface compressive stresses -interruption of crack propagation |
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True or False, brittle materials can be permanently strengthened by removing surface flaws
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False (temporary only)
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What are the two simplest and cost effective methods of removing surface flaws (to help strengthen ceramic)?
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glazing
polishing |
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When trying to strengthen brittle material by introducing residual surface compressive stresses, the body of the material us under (tensile/compressive) stress
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tensile
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What products are strengthened by the introduction of residual surface compressive stresses?
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tempered glass
pre-stressed concrete Corelle dishes |
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What are the three main ways to introduce residual surface compressive stresses?
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ion exchange
thermal tempering thermal expansion mismatch |
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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
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sodium, potassium
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Which is larger, Na or K?
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K is 36% larger
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How does the introduction of K for Na in glass add to the strength of the glass?
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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.
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GC's Tuf-Coat is a product that uses __ to strengthen the product
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ion exchange
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__ __ is used to strengthen automobile windows, plate glass windows, diving masks, etc.
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thermal tempering
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Thermal tempering works by freezing the (inner/outer) skin of molton glass by jets of (water/air)
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outer, air
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in thermal tempering, as the core solidifies, it (pushed/pulls) the outer layer creating residual compressive stress
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pulls
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Corning's Corelle for making plates and bowls is strengthened by which technique?
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thermal expansion mismatch
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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
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higher, lower
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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
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higher
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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?
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interruption of crack propagation
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what are the three different types of dispersions in the interruption of crack propagation?
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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) |
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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
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True
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Tooth reduction for ceramic restorations should be __ to __ axially and __ to __ occlusally. Why?
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1.0-1.5
1.5-2.0 to allow for adequate thickness for strength |
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Sudden changes in shape and thickness of a ceramic restoration are (more/less) likely to cause stress razors
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more
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Areas of inadequate reduction and (dull/sharp) internal line angles are most common places for failure of ceramic restorations
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sharp
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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 |
castable
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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 |
heat
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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 |
slip
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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 |
chairside
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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
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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
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Tin, Pt
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aluminous porcelain (jacket) crowns have a better "survival rate" on anteriors than posterior, T or F?
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T
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LOL??
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LOL!!!!1
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Alumina core crowns are made of __-__% alumina with an outer later of (translucent/opaque) porcelain
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40-50, translucent
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alumina core crowns have twice the flexural strength of feldspar and (higher/lower) failure in posterior crowns than anterior
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higher
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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
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high, Pt
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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
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phosphate, sand, heat, ceramming, very
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True or False, Dicor is no longer sold
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True
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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
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Match.
1. IPS empress classic 2. IPS empress 2 A. high leucite-content porcelain B. lithium disilicate |
1A, 2B
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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
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115
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Why is empress 2 heat treated?
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increase flexural strength
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The initial cost for equipment in heat-pressed ceramics is (high/low) and results in good fit and high strength
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high
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What are the three forms of In-Ceram slip-cast ceramics available?
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alumina
spinel zirconia |
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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)
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Alumina has a flexural strength of __MPa but (can/cannot) be etched and silane-treated
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400, cannot
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Spinel has a flexural strength of ___MPa and is (more/less) translucent than Alumina
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375, more
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For slip-casting, as the material's flexural strength goes up, the optical properties (decrease/increase)
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decrease
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Zirconia has a flexural strength of __MPa and is more (translucent/opaque) than alumina
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600-700, opaque
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What does CAD/CAM stand for?
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computer-aided design, computer-aided machining
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True or False, a CAD/CAM machine allows the dentist to complete posterior crowns, inlays, onlays and veneers in 1 appointment
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True
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True or False, CAD/CAM restorations cannot be stained or glazed
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False, they can
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True or False, no extra training is required to use a CAD/CAM because they're easier than pie.
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False
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Machines in CAD/CAMs have to account for the __-__% shrinkage of aluminum oxide core
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15-20
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For Porcera AllCeram, densly sintered alumina core is pressed to the new dimensions and machine, and then veneered with special (high/low) fusing porcelain
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low
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Procera AllCeram is used for ___ on anterior and posterior teeth only
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crowns
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For Cercon, a strong __-stabalized zirconia framework is milled and then veneered with sintered (translucent/opaque) feldspathic porcelain
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YtO, translucent
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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
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The flexural strength of Cercon is __ MPa
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900
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What machining product is the strongest with CAD/CAM technology?
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Lava
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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
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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
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lower
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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
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high
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The following are properties of dental ceramics:
esthetic biocompatible 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
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What is the most important property other than flexural strength?
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fracture toughness
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Random distribution of small defects (porosities, microcracks) in brittle materials that can cause strength variations is related to what?
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fracture toughness
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True or False, strength values are of limited use in designing restorations made of brittle materials
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True
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Fracture toughness is measured by the resistance of brittle materials to ___ propagation of flaws under applied stress
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catastrophic
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What is measured using Critical Stress Intensity?
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fracture toughness
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Kic is the abbreviation for what?
(the i and c are subscripts) |
critical stress intensity, a measure of fracture toughness
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What are the units of measure for critical stress intensity?
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MPa x m^(1/2)
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What is the main specimen type used to test fracture toughness?
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single-edge notch specimen
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In general, translucency (increases/decreases) as strength increases
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decreases
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What in saliva can cause crack growth and stress corrosion in glass containing ceramics resulting in decomposition of their glass structure?
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Water
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