Lecture 8 Flashcards
E. max CAD (lithium disillicate)
How does it come?
In a BLUE STATE (composed primarily of lithium metasilicate, which is easier to mill and results in lower bur wear) . AFTER milling process is completed, material is heat treated and glazed in one step, forming the final Lithium disilicate prepared for cad/cam use
All Ceramics Classifications (3)
Glass-matrix ceramics
pollycrystalline ceramics
Resin matrix ceramics
Examples of glass-matrix ceramics
feldspathic
synthetic (leucite-based, lithium disilicate (e-max), fluroapitate)
Glass-infiltrated (alumina, alumina and magnesium, alumina and zirconia)
Examples of pollycrystalline ceramics
alumina
stabilized zirconia
zirconia-toughened alumina
alumimna-toughened zirconia
Examples of resin-matrix ceramics
zirconia-silica ceramic in a resin interpenetrating phase
Examples of Feldspathic
IPS empress Esthetic, IPS empress CAD, IPS classic, Ivoclar Vivadent, Vita VMK 68
What is feldspathic made out of
Clay/Kaolin (Hydrated Aluminasilicate)
Quartz (Silica)
Feldspar (Potassium and sodium aluminasilicates)
Synthetic composed of?
silicon dioxide, potassium oxide, sodium oxide, and aluminum oxide
They can be combined with apatite crystals or LEUCITE
What does leucite do?
reinforces the glass by defecting and arresting the propagation of cracks.
Makes ceramics stronger and helps prevent cracks.
Leucite glass ceramics present excellent esthetics due to high and adjustable translucency.
Polycrystalline ceramics
Aluminious oxide
stabilized ZIRCONIA
zirconia-toughned alumina (ZTA)
Alumina toughned zirconia (ZTA and ATZ)
fine grain crystalline structure, provides strength and fracture toughness
LIMITED translucency due to the absence of glass phase
difficult to etch with hydrofluoric acid
Resin-Matrix Ceramics
Lava Ultimate
Enamic Vita
organic matrix highly filled with ceramic particles
General rules
Greater crystalline content results in higher flexural strength but also can decrease translucency
As a general rule, relationship between strength and esthetics is INVERSELY proportional
CAD/CAM Materials:
Vita Mark II (Feldspar Ceramic)
Vita Mark II presented with more translucency than IPS e.max CAD at both 0.5 and 1.0 mm
This is are most esthetic porcelain
Flexural strength 125 +/- 10 mpa
CAD/CAM Materials:
Vita Enamic
Flexural strength 170 +/- 10 mpa
VITA Enamic has a LOWER translucency than other resin ceramic hybrid materials
CAD/CAM Materials
IPS e.max: lithium disilicate glass ceramic
Flexural strength 360 +/- 40 mpa
CAD/CAM Prothesis
milling process does not create a smooth surface ready for cementation.
The ceramic material must be contoured and finished post-milling to make it ready for delivery.
Wash the crown after the milling
Polishing
maximize flexural strength
Minimizes the risk of chipping or fracture
Minimizes abrasive wear of opposing teeth and restorations
Maximizes biocampatibility by limiting adherence of bacteria to the surface of the restorations
Do you still need to polish before you glaze?
100%. all polished surfaces were significantly smoother than the positive control (glazed empressCAD samples)
Polishing
Exa cerapol wheel
Blue wheels and points
Pink wheels and points
Grey wheels and points
gross adjustments and pre-polishing (exa cerapol wheel)
Blue for adjusting porcelain
Pink for pre-polish
High shine with grey wheels
any material used to attach or cement indirect restorations to prepared teeth
Luting agents
This traditional cement acts by filling a space and binding adjacent surfaces
Non-adhesive
chemically interacts with the surface of the tooth and or restoration. Adherence or bonding to the surface is involved
adhesive
process of multilink
etch everything except zirconia
try-in patients mouth
clean with ivoclean
apply monobond to intaglio of restoration for 1 min
Resin modified glass ionomer cements
advantages and dis
chemical bond
flouride release
good compressive strength
disadvantages: expansion, soluble in oral fluids
