Today's dental materials Flashcards
what do we do after alginate
1) alginate impression
2) gypsum (microstone) to create positive replica
CAD CAM
1) models can be milled or printed
2) same with crowns
type I gold
1) soft, low stress
2) inlays
type II
1) medium, moderate stress
2) inlays and onlays
type III
1) hard, high stress
2) crowns, thick veneer crowns, short span fixed prosthesis
type IV
1) extra hard, high stress
2) thin veneer crowns, long-span fixed prosthesis, removable prosthesis
historical restorations
1) lost wax, investment, centrifugal casting
- investment
- wax pattern sprued
- base affixed to ring
- pouring investment into mold
- centrifugal casting machine
- melting gold
- cut sprue off
- polish
2) now it is milled and printed
digital dentists
1) seeing restorations with CAD/CAM with or without chairside digital scanner
2) adaptive impression scanning by 3Shape
leucite reinforced and LDS are
1) pressed
- ingots
2) milled
- blocks
zirconia
1) porcelain fused zirconia
- ingots
- bilithic
2) milled blocks
- monolithic
leucite reinforced glass ceramic
1) potassium and aluminum tectosilicate
- particle filled glass
2) esthetic with functional strength
- for anterior dentition and partial coverage for posterior teeth
- prior to LDS
3) empress I and II
4) pressed or milled
5) 1990
lithium disilicate
1) quartz
2) lithium dioxide, phosphate oxide, alumina, and potassium oxide
3) interlocking nature of crystal structure
- esthetic and strong
4) ingots (pressed) or monolithic (CAD/CAM)
5) eMAX
ivolar versatile materials
1) medium translucency and shade gradation
- full contour crowns, full contour 3 unit bridges
2) medium translucency
- same as above
3) low translucency
- above +full contour 4 unit bridges with 2 pontics + crown frameworks + 3 unit bridge framework with 2 pontics
4) medium opacity
- crown frameworks + 3 unit bridge framework with 2 pontics
what’s an ingot
1) LDS, porcelain, or metal
2) uniform size and shape that can be used for casting, pressing, or becoming part of a restoration
3) ingot is liquefied via high temperature and pressed through a casting ring
ingots are used in
1) pressed LDS
-variety of translucencies and opacities to accommodate the patient’s esthetics and clinicians demand for strength
2) layering of porcelain on zirconia (bilithic restorations)
what does pressed mean
1) heating an ingot at high temperature then heat pressing under a vacuum, fabricating a restoration through an investment
2) mostly done at dental labs
pressed components
1) heat plunger
2) ingot
3) sprue mold
4) burned out wax / pattern of restoration (wax up can be CAD/CAM)
5) investment
LDS in block form
1) intermediate form 130-160 MPa
2) after the restoration is milled, it is placed in a ceramic furnace to be crystalized, strength increased to 500 MPa (bonded)
3) metal lug assures positive lock in the mill
crystallization of LDS
1) the LDS grows, interlocks, and concentrates
2) inreasing its flexural strength during this process
3) pre-crystallized
- 40% isolated lithium metasilicate
- crystals in a glass matrix
4) IPS Emax CAD after firing
- 70% lithium disilicate
- crystals in a glass matrix
zirconia
1) zirconia dioxide
2) two types:
- tetragonal and cubic
3) tetragonal is used for toughening
4) cubic is used to increase translucency
5) balance the two for strength and aesthetics
6) needs to be sintered at 1500-1600C to enact state change
- heat shrinkage 20-25%
- stronger and more translucent
leucite reinforced strength
1) 160-185 MPa
- glaze up to 240 MPa
lithium disilicate strength
1) 400-500 MPa
- high value assumes bonded
zirconia strength
1) bilithic
- 1000 MPa
2) Milled
- 500-1000 MPa
where to use leucite reinforced
1) veneers
2) inlays/onlays
3) must bond
where to use LDS
1) veneers (0.4)
2) inlays/onlays
3) crowns 1.0 mm bonded
4) bridges (to second premolar)
5) 12 mm connector
zirconia uses
1) inlays/onlays
2) crowns 1 mm
3) no bond
4) bridges 12 mm
5) anterior crowns (bilithic)
how is strength measured
1) flexural strength
- applying a load to a material specimen that is supported at each end, which combines the forces found in compression and tension
2) MPa: a unit for measure that represents how much stress a material can withstand without failing
esthetics and functional medicine
1) knowledge of the material is key
2) adhesives play an integral role in success
- bonded Emax is much stronger than unbonded
- short zirconia or Emax in posterior require bonding for retention
esthetics ranking
1) leucite (best)
2) LDS and bilithic zirconia
3) monolithic zirconia (worst)