pressable ceramics
TRANSCRIPT
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CONTENTS:• Introduction
• Definition For Dental Ceramics
• Definition For Pressable Ceramics
• History
• Various All Ceramic Systems
• Classification
• Pressable Ceramics
• History
• Generation Of Pressable Ceramics
• Cerestore – Development
Fabrication
Advantage
Disadvantage2
IPS Empress - Materials And Composition
Special Furnace
Fabrication
Advantage
Disadvantage
IPS Empress 2- Indication
Properties
Fabrication Method
Advantage
Disadvantage
IPS Emax Press - Microstructure
Composition
Properties
OPC 3G- Development
Indication
Properties 3
INTRODUCTION
There have been significant technological advances in
the field of dental ceramics over the last 10 years which
have made a corresponding increase in the number of
materials available. Improvements in strength, clinical
performance, and longevity have made all ceramic
restorations more popular and more predictable
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DEFINITION FOR DENTAL CERAMICS⁶
An inorganic compound with non metallic properties typically
consisting of oxygen and one or more metallic or semi
metallic elements (e.g ;Aluminium, Calcium, Lithium,
Mangnesium, Potassium, Sodium, Silicon, Tin , Titanium And
Zirconium)that is formulated to produce the whole or part of
a ceramic based dental prosthesis
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DEFINITION FOR PRESSABLE CERAMICS ⁶
• A ceramic that can be heated to a specified temperature and
forced under pressure to fill a cavity in a refractory mold
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HISTORY OF DENTAL CERAMICS ⁶
• 1789-first porcelain tooth material by a French dentist De
Chemant
• 1774- mineral paste teeth by Duchateau in England
• 1808-terrometallic porcelain teeth by Italian dentist Fonzi
• 1817- Planteu introduced porcelain teeth in US
• 1837- Ash developed improved version of porcelain teeth
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• 1903 – Dr.Charless introduced ceramic crowns in dentistry he
fabricate ceramic crown using platinum foil matrix and high
fusing feldspathic porcelain excellent esthetics but low
flexural strength resulted in failure
• 1965- dental aluminous core Porcelain by Mclean and Huges
• 1984- Dicor by Adair and Grossman
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VARIOUS ALL CERAMIC SYSTEMS
Aluminous core ceramics
Slip cast ceramics
Heat pressed ceramics
Machined ceramics
Machined and sintered ceramics
Metal reinforced system
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MICROSTRUCTURAL CLASSIFICATION⁵
Category 1: Glass-based systems (mainly silica)
Category 2: Glass-based systems (mainly silica) with fillers usually crystalline
(typically leucite or a different high-fusing glass)
a) Low-to-moderate leucite-containing feldspathic glass
b) High-leucite (approx. 50%)-containing glass, glass-ceramics (Eg: IPS
Empress)
c) Lithium disilicate glass-ceramics (IPS e.max® pressable and machinable
ceramics)
Category 3: Crystalline-based systems with glass fillers (mainly alumina)
Category 4: Polycrystalline solids (alumina and zirconia)
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PRESSABLE CERAMICS
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History
• Early 1990 - pressable glass ceramic(ips impress) containing
approximately 34 vol% leucite was introduced that provide a
strength and marginal adaptation similar to dicor glass
ceramic but do not require no specialized crystallization
treatment
• They are not indicated to produce FPD
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• Late 1990- Ips Empress 2 more fracture resistant with 70 vol %
Lithia Disilcate crystal was introduced
• used for 3 unit FPD up to premolar
• The fracture toughness of Ips Empress 2 glass ceramic(3.3mpa
m⅟2)is 2.5 times grater than that of Ips Empress glass ceramic
(1.3 mpa m⅟2)
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VARIOUS GENERATION OF PRESSABLE CERAMICS
BY PRESURE MOLDING AND SINTERING
• Shrink free ceramics –
e.g.; cerestore
alceram
BY HEAT TRANSFER MOLDED
• Leucite reinforced glass ceramic- e.g.; Ips empress
Optec opc
• Lithia reinforced glass ceramic – e.g.; Ips empress 2
Ips emax empress
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CERESTORE
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Development
• - developed by the Coors Biomedical Co. and later sold to
Johnson & Johnson.
• Shrink free ceramic
composition
• Consist of – Al₂O₃ and MgO mixed with barium glass frits
• Flexural strength approx 150 Mpa
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FABRICATION
• Transfer molding process
• The Cerestore crown was veneered with conventional
porcelains
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Preheated ,uncured molding compound is placed in the transfer pot
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• A hydraulically powered
plunger pushes the molding
compound through the
sprue in to the preheated
mould cavity
• The mold remain closed
until the material inside is
cured or cooled
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• The mold is split to free the
product with the help of
ejector pins
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• The splash and sprue
material is trimmed off
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ADVANTAGE OVER PJC
• The use of a shrink-free ceramic coping formed on an epoxy
die by a transfer molding process overcame the limits and
firing shrinkage of conventionally produced aluminous
porcelain jacket crown.
• On firing transformation produces Magnesium Aluminate
spinel which occupies a greater volume than the original
mixed oxides compensate for the conventional firing
shrinkage
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ADVANTAGE
• Good dimensional stability
• Better accuracy of fit and marginal integrity
• Esthetics
• Biocompatible
• Low thermal conductivity
• Low coefficient of thermal expansion
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DISADVANTAGE
• Complexity of the fabrication process
• Need for specialized fabrication equipment
• Inadequate flexural strength
• Poor abrasion resistance
• High clinical failure rates
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ALCERAM
• Modification of cerestore with high flexural strength is marketed under the name alceram
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IPS EMPRESS⁴
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DEVELOPMENT
• First described by wohlwend and scharer
• The IPS-Empress system was developed at the University of
Zurich, Zurich, Switzerland, in 1983.
• Ivoclar Vivadent took over the development project in 1986
and presented it to the profession in 1990.
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• First generation heat-pressed ceramics contain between 35
and 45 vol % Leucite as crystalline phase
• Flexural strength and fracture toughness values that are about
two times higher than those of feldspathic porcelains
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MICROSTRUCTURE AND COMPOSITIONCOMPOSITION IN WT%:
• 63% - sio₂,
• 17.7 % - AI₂0₃
• 11.2 % - K₂O,
• 4.6 % - Na₂O,
• 0.6 % - B₂O₃
• 0.4% - CeO₂
• 1.6% - CaO,
• 0.7 % - BaO,
• 0.2 % - TIO₂,
• The crystalline part of the
ceramic consists of leucite
crystals,
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PROPRETIES
• Flexural strength - 112±10 mpa
• Fracture toughness - 1.3±0.1 mpa˙m⅟2
• Thermal exoansion coefficient - 15.0±0.25 ppm/ ⁰c
• Chemical durrability - 100-200 ug/cm²
• Pressing temperature - 1180 ⁰c
• Veneering temperature - 910 ⁰c
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USES
• Laminate veneers and full crown for anterior teeth
• Inlays ,onlays and partial coverage crowns
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Ingots
• Leucite containing Glass ceramic provided as core ingots that
are heated and pressed until the ingot flows into a mold
• It contains a higher concentration of leucite crystals that
increase the resistance to crack propagation
• The hot pressing process occurs over a 45 min period at a
high temperature to produce the ceramic substructure
• This crown can be either stained and glazed or built up using
a conventional layering technique33
A SPECIAL FURNACE - (EMPRESS EP 500)
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AUTOMATIC FURNACE
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A SPECIAL FURNACE - (EMPRESS EP 500)
contains an:
• enlarged heat dome,
• a pneumatic pressure system,
• a reducing valve,
• a manometer to control the pressure;
• an inductive displacement transducer is mounted on top of
the furnace and is connected to the pneumatic plunger
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FABRICATION
• The crown or inlay was waxed and placed on a specially
designed cylindrical crucible former and invested using a
phosphate-bonded investment.
• The mold was heated in a burnout furnace to 850°C.
• The cylindrical opening into the mold was filled with a ceramic
ingot and an Al₂O₃ pushing rod.
• The assembly was then placed into the preheated furnace
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• The inlays must be waxed
and placed on a specially
designed cylindrical crucible
former
• Ceramic ingots are
preshaded and
precerammed.
• For the inlay technique,
translucent material is used.
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• After filling the cylindrical opening with an already
preheated ceramic ingot and an AL₂O₃ pushing rod, the cast
must be placed into the preheated Empress furnace.
• The aluminium oxide pushing rod is used to transfer the
pressure to the ceramic material
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• After the press procedure, the inlays are devested and
prepared for further treatments
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• The occlusal surface and the inner surface can be covered
with a thin layer of surface stains. The occlusal surface will be
covered with a glaze
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• Inlays can be made more simply and have good marginal
integrity when placed
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• The main advantage of the IPS-Empress system is that through the
injection-molding process, which involves the use of heat and
pressure,
• The leucite crystals incorporated in the material create barriers that
counteract the buildup of the tensile stresses that predispose to
formation of micro cracks.
• Thus the added leucite crystals improve flexural strength and
fracture resistance through so-called dispersion strengthening.
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• The crystals act as “roadblocks” in preventing crack
propagation, so that the restoration does not undergo
catastrophic failure during function.
• In addition, the combination of heat and pressure used in the
casting process reduces the amount of ceramic shrinkage and
results in higher flexural strength.
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AUTOMATIC FURNACE
• Rate of temperature increase varied from 5°C to 2O⁰C/min,
• Furnace can be heated to 1,200°C,
• Holding time at the final temperature varied from 0 to 60
minutes.
• If the pneumatic plunger does not continue to move more
than 0.3 mm/min, the pressure maintenance time will be
activated.
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• A pressure maintenance of 1 to 4 minutes is necessary
depending on the thickness of the cavity that has to be filled;
the time can be varied from 1 to 20 minutes,
• The press procedure is performed in a vacuum, and the
beginning and ending points for the vacuum application can
be programmed
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• When the start button is pushed, the furnace heats up
automatically to the programmed press temperature
(1,150°C),
• After a 20-minute holding time at this temperature the press
procedure was activated and the then-plastic glass-ceramic
material was pressed (0.3 to 0.4 Mpa) into the mold.
• The mold was filled with the glass-ceramic material and the
furnace stopped automatically.
• The ceramic restorations were devested and prepared for
further treatments48
ADVANTAGE
• Lack of metal
• Translucent ceramic core
• Moderately high flexural strength
• Fracture resistance
• Excellent fit
• Excellent esthetics
• Etchable
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DISADVANTAGE
• Potential to fracture in posterior areas
• Need to use resin cement to bond the crown
micromechanically to tooth structure
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IPS EMPRESS 2
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IPS EMPRESS 2
• Second generation of heat pressed dental ceramics
• contain about 65 vol % lithium Disilcate as the main crystalline
phase.
• The material is pressed at 920⁰c and layered with a glass containing
some dispersed apatite crystals
• Their strength is more than twice that of first generation leucite-
reinforced all-ceramics and their good performance has led to their
expanded use to restorations produced by machining.
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MICROSTRUCTURE HEAT-PRESSED LITHIUM DISILCATE GLASS-CERAMIC
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PHYSICAL PROPERTIES
• Flexural strength - 400±40 mpa
• Fractural toughness - 3.3±0.3 mpa˙m⅟2
• Coefficient of thermal expansion - 10.6+0.25 ppm/ ⁰c
• Chemical durability - 50 ug/cm²
• Press temperature - 920⁰c
• Firing temperature - 800⁰c
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INDICATIONS
• Anterior and posterior Crown
• Anterior three unit FPDs
• Inlays and onlays
• Premolar FPD
Other application: cosmopost and Ips empress cosmos ingot –
core built up system with the prefabricated zircon oxide root
canal posts and the optimally coordinated ingot
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FABRICATION PROCEDURE
• Wax the restoration to final contour ,sprue, and invest as with
conventional gold casting
• If the veneering technique is used, only body porcelain shape
is used
• Heat the investment to 800⁰c to burn out the wax pattern
• Insert a ceramic ingot of the appropriate shad and alumina
plunger in the sprue and place the refractory in the special
pressing furnace
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• After heating to 1165⁰c, the softened ceramic is slowly
pressed into the mold under vacuum
• After pressing recover the restoration from the investment by
airborne particle abrasion ,remove the sprue and refit in to
the die .
• Esthetics can be enhanced by applying an enamel layer of
matching porcelain or by adding surface characterization
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1.Wax and invest 2.Press ceramic
4.Framework 5.Veneer buildup 6.Final Bridge
3.Divest pressing
ADVANTAGE
• Excellent translucency corresponding to natural teeth
• High mechanical strength
• Superior opalescence/ fluorescence
• Wear comparable to natural dentition
• Low bacterial adhesion
• Opacity
• Controlled crystallization
• Can be bonded as well as conventionally cemented
• Superior fracture toughness
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IPS EMAX PRESSⁱ
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IPS e.max is an all-ceramic system that consists of the
following five components:
• • IPS e.max Press (lithium Disilcate glass-ceramic ingot for the
press technique)
• • IPS e.max ZirPress (fluorapatite glass-ceramic ingot for the
press-on technique)
• • IPS e.max CAD (lithium Disilcate glass-ceramic block for the
CAD/CAM technique)
• • IPS e.max Zircon (zirconium oxide block for the CAD/CAM
technique)
• • IPS e.max Ceram (fluorapatite veneering ceramic)
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INGOTS
• IPS e.max Press is a lithium Disilcate glass ceramic ingot for
use with the press Technique
• The ingots are available in two degrees of opacity
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• These ingots have been developed on the basis of a lithium silicate
glass ceramic .
• The ingots are produced by bulk casting.
• A continuous manufacturing process based on glass technology
(casting/pressing procedure) is utilized in the manufacture of the
ingots.
• This new technology uses optimized processing parameters, which
prevent the formation of defects (pores, pigments, etc) in the bulk
of the ingot.
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MICROSTRUCTURE
• The microstructure of IPS e.max Press consists of lithium
Disilcate crystals (approx. 70%), which are embedded in a
glassy matrix.
• Lithium Disilcate, the main crystal phase, consists of needle-
like crystals
• The crystals measure 3 to 6 μm in length.
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COMPOSITION
Standard composition: (in wt %)
• SiO₂ 57.0 – 80.0
• Li₂O 11.0 – 19.0
• K₂O 0.0 – 13.0
• P₂O₅ 0.0 – 11.0
• ZrO₂ 0.0 – 8.0
• ZnO 0.0 – 8.0
• other oxides 0.0 – 10.0
• +coloring oxides 0.0 – 8.0
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INDICATIONS
• Thin veneers (0.3 mm)
• Inlays , onlays, occlusal veneers
• Crowns in the anterior and posterior region
• Bridges in the anterior and premolar region
• Implant superstructures
• Hybrid abutments and abutment crowns
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PHYSICAL PROPERTIES
68
FLEXURAL STRENGTH
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• The strength values of IPS e.max Press and IPS Empress2,
which are higher than IPS Empress, are attributable to the
composition of these materials (lithium disilicate crystals).
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FRACTURE STRENGTH OF ANTERIOR BRIDGES
• The fatigue strength of IPS e.max Press by far surpasses the
maximum load that may be exerted on the material under
natural conditions.
• It can be assumed that three-unit anterior bridges made of
IPS e.max Press are long lastingly resistant to fracture, if
constructed according to the Instructions for Use
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FRACTURE STRENGTH OF THREE-UNIT POSTERIOR BRIDGES
• The highest fracture strength was measured for anatomically
pressed bridges.
• The fracture strength of veneered frameworks is higher than
that of frameworks without veneering.
• This increase in fracture load may be attributed to the size of
the cross-section, which is larger in veneered frameworks
than in non-veneered ones.
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FRACTURE STRENGTH OF PARTIAL CROWNS
• The fracture strength measured in the posterior region did
not significantly differ from that of the natural, unprepared
teeth.
MARGINAL FIT
• Marginal gap in IPS emax empress - 29.22 um
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BIOCOMPATIBILITY
• All-ceramic materials are known for their high levels of
biocompatibility
CYTOTOXICITY
• No cytotoxic potential has been observed in IPS e.max Press
SENSITIZATION, IRRITATION
• Ceramic has no or, compared to other dental materials very
little potential to cause irritation or sensitizing reactions.
ADVANTAGES
• Cost-effective, esthetic alternative to full cast crowns
• High esthetics, even with different preparation shades
• Wide range of indications from thin veneers to three unit
bridges
• Highly esthetic alternative to ZrO2-supported crowns
• Self-adhesive or conventional cementation of crowns and
bridges
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OPC 3G
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DEVELOPMENT
• Third generation pressable ceramics
• Porcelain is twice the stregnth of previous generation pressed
ceramics
• Size of leucite crystals reduced and improved its distribution
without reducing the total crystalline content
78
PROPERTIES
• Optimally pressed cermic is comprised of combination of
materials that enhance ability to mimic natural dentition
• Compressive strength -23,000psi
• Provides high degree of fit to the tooth
• Increase load bearing capacity
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CEMENTATION
• Variolink II – DUAL CURING
• Variolink veneer- LIGHT CURING
• Multilink automix
• Speed cem
• Variolink speed
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MULTILINK® AUTOMIX
• is a universal, self-etching composite system that is directly
applied without mixing.
• Multilink Primer seals the dentin and ensures a good
marginal seal as well as high bonding strength.
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Multilink speed
Standard composition (in wt%) Base Catalyst
• Dimethacrylates 23.3 26.0
• Ytterbium trifluoride 45.2
• Co-polymer - 22.6
• silicon dioxide 75.0 2.2
• Adhesive monomer - 3.1
• Initiators, stabilizers and pigments 1.7 0.9
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Variolink II
Monomer matrix:
• Bis gma
• Urethrane dimethacrylate
• Triethylene glycol dimethacrylate
Inorganic fillers :
• BARIUM GLASS
• Yettrium trifluoride
• Ba-al fluorosilicate glass
• Spheroid mixed oxide
Additional contents:
Catalyst ,stabilisers , pigments 84
SPEED CEM
Self adhesive , self curing resin cement with light curing
option
Advantage
• No phosphoric acid etching
• No primer , bonding agents or adhesives for enamel and
dentin
• Good bonding values
• High strength
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Standard composition (in wt%) Base Catalyst
• Dimethacrylates 23.3 26.0
• Ytterbium trifluoride 45.2
• Co-polymer - 22.6
• silicon dioxide 75.0 2.2
• Adhesive monomer - 3.1
• Initiators, stabilizers and pigments 1.7 0.9
87
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• Flexural strength – force per unit area at the point of fracture of a
test specimen subjected to flexural loading
• Tensile strength- tensile stress at the point of fracture
• Fracture toughness – the critical stress intensity factor at the
beginning of rapid propagation in a solid containing a crack known
of shape and size
• Coefficient of thermal expansion - change in length per unit of
original length of a material when its temperature raised to 1⁰k
90
COMPARISION OF IPS EMPRESS IPS EMPRESS 2 IPS EMAX EMPRESS
91
Ips empress Ips empress 2 Ips emax press
Microstructure leucite crystals lithium Disilcate glass ceramic
lithium Disilcate glass ceramiccrystals measure 3 to 6 μm in length.
Indication •single-unit restorations
•Crown•Anterior 3 unit FPDs•Inlays and onlays
• veneer , Inlays/onlays,• Crowns and bridges in the anterior and posterior region,• Implant superstructures,• Hybrid abutments and abutment crowns
Properties Flexural strength - 112±10 mpaFracture toughness -1.3±0.1mpa˙m⅟2
Thermal expansion coefficient -15.0±0.25ppm/⁰cChemical durrability-100-200 ug/cm²Pressing temp - 1180 ⁰cVeneering temp - 910 ⁰c
Flexural strength - 400±40 mpaFractural toughness - 3.3±0.3 mpa˙m⅟2Coefficient of thermal expansion -10.6+0.25 ppm/ ⁰cChemical durability - 50 ug/cm²Press temperature - 920⁰cFiring temperature - 800⁰c
•Flexural strength – 400±40 mpa
•Fracture toughness 2.5 –3.0 Mpa.m⅟₂•Coefficient of thermal expansion – 10.55±0.35 10‾⁶k‾ ˡ •Chemical solubility 40±10 ug/cm²
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Advantage •Translucent ceramic core•Moderately high flexural strength•Fracture resistance•Excellent fitesthetics
•Excellent translucency• High mechanical strength•Superior opalescence/ fluorescence•Wear comparable to natural dentition•Low bacterial adhesion
•Cost-effective, • High esthetics,•Self-adhesive or conventional cementation of crowns and bridges
93
CONCLUSION
• Restorative dentistry faces new challenges in adopting
emerging technologies related to dental materials and in
meeting patient demand . with the increasing clinical success
of such alternative restorative materials, the use of metallic
restoration in the posterior teeth is declining .
94
REFERENCES
1. Ips emax press –scientific documentation ivocular vivadent
2. Ceramics for dental application- a review;isabella denry ,materials -
January 2010
3. Longevity and clinical performance of Ips empress ceramic restorations a
literary review jean François brochu –journal of Canadian dental
association April 2002,vol.68,no.4
4. Heat pressed ceramics –j.k.dong –international journal of prosthodontics
–vol.5 number 1 ,1992
5. Ceramics in dentistry – narashima ragavan ,
6. Philips science of dental material -11th edition –kenneth j anusavice
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