pressable ceramics

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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

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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

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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

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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

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COMPARISION OF IPS EMPRESS IPS EMPRESS 2 IPS EMAX EMPRESS

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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

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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 .

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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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