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CERAMICS

Apr 11, 2023 2

• 1.What are ceramics?• 2.Evolution & history

• 3.Classification of dental ceramics

• 4. methods of strengthening ceramics• 5. PFM• 6. All- Ceramic

• Coventional slurry• Castable ceramics• Pressable ceramics• Infiltrated ceramics• Machinalble ceramics

• 7.Clinical significanc and selection criteria• 8.Conclusion• 9.References

CONTENTS

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What are ceramics?

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DEFINITIONSCeramic is derived from Ceramics is taken from the Greek word

“keramos ”

meaning burnt clay

ceramics: It is defined as any product made essentially from metal oxides and non-metallic material by firing at high temperature to achieve desirable properties

Porcelain : a ceramic material formed of infusible elements joined by lower fusing materials. Most dental porcelains are glasses and are used in fabrication of teeth for dentures, pontics & facings, crowns, inlays, onlays and other restorations. (G.P.T 7)

Denture teeth &

Dentures -Duchateau 1774Ceramic paintings and Vases

HISTORY OF CERAMICS

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1887 1903 -PJC by CH. Land (platinum foil technique)

1962 PFM – Weinstein and Weinstein patented formulation of feldspathic porcelain

1965 McLean and Hughes aluminium core porcelain

1957 Vines and Sommelman – Vaccum firing

1728 – Pierre Fauchard, a French dentist first proposed the use of porcelain in dentistry. He suggested the use of jeweler’s enamel to fabricate artificial teeth

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• 1963- Vita Zahnfabrik gave the first commercial

porcelain

• 1980 - In ceram-slip casting, castable ceramics

• Latest 1990’s – machinable ceramics(CAD\CAM)

Evolution of all ceramic restorations :

Apr 11, 2023 8COMPOSITION

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Feldspar - 75-85 %

• Basic glass former• Makes particles to coalesce together.• This is called sintering.

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Kaolin / clay : 4-5 %

• Binder• Forms a sticky mass which allows unfired

porcelain to be easily worked and molded.• Its white in color and reduces translucency

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Quartz :13-14%

• Basic filler• It imparts more strength, firmness and

translucency. • It gives stability of mass during heating

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OTHER MINOR COMPONENTS

• Fluxes- oxide

• Metallic pigments- colour matching– Brown- iron oxide– Green-copper oxide– Yellow brown- titanium oxide– Blue – cobalt oxide– Pink – chromium, tin oxide

• stains and colour modifiers

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CLASSIFICATION

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Classification of ceramics :

1. By content :

- Regular feldspathic porcelain

- Aluminous porcelain

- Leucite reinforced porcelain

- Glass infiltrated alumina

- Glass infiltrated spinel

2. By their area of application :

-core porcelain

-body dentin porcelain

- gingival dentin porcelain

-incisal enamel

-Cervical porcelain

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3.By use :

-core ceramic

-veneer ceramic

-margin ceramic

-opaque ceramic

-dentin ceramic

-enamel ceramic

-stain ceramic

4. By processing method :

-sintering

-casting

- machining

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5. By their firing temperature :

-high fusing : 1300 c - medium fusing : 1100-13000 c -low fusing : 850 – 1100 c -ultra low fusing : less than 850C

6. By method of firing ; - Air fired -vaccum fired

- diffusable gas

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ADVANTAGES OF CERAMICS:• High abrasion resistance• Excellent thermal and electrical

insulators • Excellent esthetic qualities • Translucency• Color stability • Capacity of pigmentation • Stain resistance• Enhanced polishability • High durable

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DISADVANTAGES:

• Highly brittle • Excessive wear of opposing teeth• High firing shrinkage

Apr 11, 2023 20Crack Growth

Why are Ceramics weak ?

1.Brittle – Covalent bonds2. Inherent flaws- eg. Sharp notches,

surface scratches and defects

Covalent bonds

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1. Development of residual comressive stresses:– Ion exchange– Thermal tempering– Thermal compatibility

2. Interruption of crack propagation:– Addition of tougher material e.g. DICOR– Change in crystalline structure e.g. particle

stabilized zirconia

Methods of strengthening brittle materials

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Development of Residual Compressive Stresses

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Ion Exchange (Sometimes called Chemical tempering) •In this process the potassium ions are exchanged for the sodium ions.•By placing sodium containing glass in in a bath of molten potassium nitrate

Larger K+ ions (about 35%) Smaller Na+ ions

•Creating large compressive stresses 700Mpa/1,00,000psi

Anusavice et al,1994

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Thermal tempering

1st stage •surface of the object while it is still hot, and in the softened (molten) state

2nd stage •by rapidly cooling (quenching) produces a skin of rigid glass surrounding a soft molten core.

3rd stage • molten core solidifies and , as it shrinks, creates residual tensile stresses in the core and residual compressive stresses within the outer surface

DeHoff and Anusavice ,1992

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Thermal compatibility (Thermal expansion coefficient mismatch)

• The metal and porcelain selected should have a slight mismatch in their thermal contraction coefficients.

•This mismatch leaves the porcelain in residual compression and provides additional strength for the restoration.

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Interruption of Crack Propagation Methods

q Dispersion Strengtheningq Transformation toughening

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Dispersion strengthening :

•Ceramics in its glass phase can be strengthened by increasing a crystal content by adding material like:-

• Leucite • Lithia disilicate• Alumina• Magnesia alumina spinel

•The glass is toughened and strengthened, because the crack cannot penetrate these particles as easily as it can the glass.•E.g. IPS Empress, InCeram Alumina

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Transformation toughening

• crack cannot penetrate easily through stabilized particles.•E.g. ZIRCONIA (ZRO2) is added with YTTRIA (Y2O3) to stabilize•The zirconia tranforms :- > 3 vol%

Unstable tetrahedral lattice Stable monoclinic lattice at 1150C

This increased volume places the crack under a state of compressive stress and crack propagation is arrested.

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In a study by Preis V et al they checked the wear performance of monolithic dental ceramics by ANNOVA method and found that the monolithic ceramic like zirconia had increase strength and, the zirconia showed no wear.

Quintessence Int. 2013 Feb 14. doi: 10.3290/j.qi.a29151. [Epub ahead of print]Wear performance of monolithic dental ceramics with different surface treatments.Preis V, Weiser F, Handel G, Rosentritt M.

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METAL CERAMIC RESTORATIONS

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METAL CERAMIC RESTORATIONS

• Def: refers to partial or full crown made with a metal substructure, to which porcelain is bonded for aesthetic enhancement, via an intermediate metal oxide layer.

– Porcelain fused to metal PFM– Ceramo metal restoration – Porcelain to metal PTM

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Need for fusing ceramic to metal

• Main drawback of dental porcelain– Low tensile and shear strength.– Brittle material – very low elastic deformation

- Brittle fracture.

METAL CERAMIC RESTORATION

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ALLOYS USED IN METAL-CERAMIC RESTORATION

• Noble metal alloy• Low gold alloy• Silver – palladium alloy• Base metal alloy (eg. Ni,

Cr, Co)

According to noble metal content ,metal –ceramics are broadly classified by the ADA (1984)

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BONDING MECHANISMS BETWEEN CERAMIC

AND METAL

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Methods of attaching porcelain to metal The ceramo – metallic bond is probably derived from three main components :

•Chemical bonding• Molecular bonding• Mechanical bonding• Compression bonding

(Vickery & Badinelli 1968; McLean 1979, Cascone 1977).

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The potential of alloys to bond to porcelain is largely determined by the formation of adherent oxides during the degassing cycle.

CHEMICAL BONDING

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Casting

Heat degassing treatment

Finishing

Sandblasting

Condesation of procelain

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Molecular bonding

•The metal surface oxide acts as a permanent component of the bond like a sandwiched structure, where it is separately bonded to the metal substrate and to the porcelain

•Wetting of the metallic substrate by the glassy porcelain by interatomic forces is facilitated. (McLean and Sced, 1976).

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Mechanical Bonding : Micro-abrasion or surface roughness produced by sandblasting can provide mechanical 'keying' and increase the surface area of porcelain attachment (mcLean and Sced 1976 ,Lugassy 1977 ).

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Compression Bonding : By the process of thermal contraction when an alloy with a slightly higher coefficient of thermal expansion than poreclain is used ,it causes the porcelain to contract (shrink or draw ) towards the coping when the restoration cools after firing

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Vander Waals Force :• It is based on mutual attraction of charged molecules.•Although their role is not significant in the actual bonding, they help in initiation of molecular/ chemical bond.

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Bonding of Porcelain to Metal by Atypical methods :•   Electro deposition .• Other Methods : The Foil Crown Systems E.g.; Captek system, The Renaissance system, Ceplatec system, Sunrise Crown, Flex Bond , Platideck .

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Where do these bonds fail?

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Types of interfacial bond failure occurs at primarily three sites

Ø Along the interfacial region between opaque porcelain (P) and the interaction zone(I) the between porcelain and the metal substrate.Ø Within the interaction zone.Ø Between the metal and the interaction zone

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DRAWBACK

Unsatisfactory esthetic result due to metal exposure!!

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ALL CERAMICS metal free ceramics

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CLASSIFICATION1. CONVENTIONAL POWDER & SLURRY CERAMICS

– HI-CERAM ( ALUMINA REINFORCED)– OPTEC HSP(LEUCITE REINFORCED)– DUCERAM LFC

2. CASTABLE ALL CERAMIC RESTORATIONS– Di-Cor– Cerestore

3. PRESSABLE ALL CERAMIC RESTORATIONS– IPS EMPRESS– IPS EMPRESS 2

4. INFILTRATED CERAMICS– In ceram Alumina– In ceram spinel– In ceram zirconia

5. MACHINABLE ALL CERAMIC RESTORATIONS– CAD/CAM Technology

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CONVENTIONAL POWDER & SLURRY CERAMICS

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ALUMINOUS PORCELAIN JACKET CROWN

( HI – CERAM )

• -McLean and Hughes in 1965, introduced porcelain jacket crown with aluminous core to improve the strength of traditional PJC.

• -Increased content of alumina - Al203 ( 40-50%)

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PROCESSING- Platinum foil technique

• Finished Cores• Master model with

dies • Platinum foil adapted to

die

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• PROPERTIES :

Compressive strength: 3,16000 psiTransverse strength : 20000 psiShear strength : 21 000 psiModulus of rupture : 15000 psi

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OTHER TYPES:-

• OPTEC HSP(LEUCITE REINFORCED)• DUCERAM LFC

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• ADVANTAGES :-Lack of metal or opaque substructure-Good translucency-Moderate flexural strength

• DISADVANTAGES:-Potential fracture of posterior teeth-Increased leucite content leads to high in-vitro wear of teeth

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1. Mc lean 1979 Five year failure rate • 2% for anteriors • 15% for posteriors

2. Seiber et al 1981 :light reflection better than porcelain fused to metal

STUDIES

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CASTABLE CERAMIC RESTORATIONS

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DI-COR

Composition : TETRA SILICIC FLUOROMICA GLASS CERAMIC.

Mica crystals Feldspathic porcelain

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Wax pattern Spruing InvestingBurnout

Divesting Cast glass coping Ceramming

17500C for 1\2hr450 0Cfor 1\2 hr

Centrifugal casting 26000 f

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Ceramming Ceramming oven Crystallised glass coping

Conventional porcelain application & Firing Finished crown

Cerramming done from room temparature- 19000 f for 1½ hrs and sustained for 6hrs in order to form tetra silicic flouro mica crystals

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PROPERTIES :

•CHAMELEON LAYER

•Flexural strength 81 ± 6.8 Mpa

•Strength-440-505 Khn

Marginal adaptation :

Weaver et al 1988 – conducted a study on 10 dicor crowns

Marginal opening – 57 ± 9 µm .

Biocompatibility :

Less bacterial counts

Reason : smooth surface, low surface tension, fluoride content.

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Esthetics :

Gross man and Adiar :

•Hue and chroma of metal ceramics and Castable ceramics matched natural teeth.

•Value of only Castable ceramics matched natural teeth.

•Presence of mica crystals scatter light similar to enamel rods.

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Survival rate :

Kenneth et al 1999 - 14yr study

•Crowns 82%

•Cores 100%

•Inlay and onlay 90%

•Partial coverage 92%

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A FEM Study was done to check the stress distribution in a 0.5 mm thick molar DICOR crown loaded on the occlusal surface. The maximum principal tensile stress is located directly below the point of occlusal loading within the internal surface of the crown

Esiquivel JF, ceramic design concept based on stress distribution: compend contin educ dent,21: 649-653

;

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PRESSABLE CERAMICS

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Also called injection molded glass ceramic, leucite reinforced hot pressed glass ceramic

TYPES:-1.IPS EMPRESS

• Leucite reinforced 2.IPS EMPRESS 2

• Lithium disilicate reinforced

Leucite content

Conventional Porcelain

Dicor Glass-ceramic

IPS Empress Pressable ceramic

30-35% 50-60% 80-85%

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Supplied in pre-cerammed and pre-coloured ingots

Processing

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Wax pattern

Ceramic ingot & Al plunger

Investing

Pressing under vaccum 11500C Sprue removal

Burn out 8500 C

26 min hold

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IPS Empress

IPS Empress 2 (frame work)

Flexural strength

Upto 150 MPa

> 400 Mpa

Clinical survival :

Deniz G in 2002 : 95% survival 2-4 years

Marginal adaptation :

Shearer et al in 1996 : better marginal adaptation with hot pressed ceramics than aluminous core material.

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INFILTERED CERAMICS

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In-ceram Alumina In-ceram Spinell

In-ceram Zirconia

INFILTERED CERAMICS

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PROCESSING: by SLIP CAST TECHNIQUE

Ultra sonic device for slip making

painted on refractory die

Additional layerAl2O3 slip

10 hrs 1120 0C- 2hrs

Shrinkage of dies

Glass infiltration 4hrs 11000C

Finished crowns

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Probster et al found after a four year clinical study that the

Strength of In-Ceram > IPS Empress < PFM

Four year clinical study of glass-infiltrated, sintered alumina crowns

Journal of Oral RehabilitationVolume 23, Issue 3, pages 147–151, March 1996

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MACHINABLE CERAMICS

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Application of CAD/ CAM techniques was actively pursued by three groups of researches :-

•France- by Henson International

•Switzerland- University of Zurich and Brains, Brandestini Instruments

•United states of America- University of Minnesota

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From 1988, machined ceramics came into being. there are 2 major systems for the fabrication of this technique

1. Analogous systems:-Copy milling / grinding technique

2.digital systems:-cad-cam technology

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Copy milling / grinding technique

•Fabrication of proto type•Replica of inlay/crown is made.•Its fixed on copying device•Transferred on to chosen material

Materials used: Composite ---sono erosion--sonotrodesceramic----- sono erosion—sonotrodesmetal-------spark erosion---dielectric fluid

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CELAY SYSTEM

Switzerland-------1992High precision manually operatedKey duplicationBlue light cured resin

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Advantage : recreation of all surfaces.

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DIGITAL SYSTEMS: CAD-CAM(10-15mins)

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Mormann and Brandestini was the first ones to use cad- cam device in 1988.the first model which came was called :-

• CEREC 1• CEREC 2• CEREC 3• CEREC 3D

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Cerec 1.

West germany-----siemens group.Ceramic reconstruction system.

Consists of:• video camera(scan head).•Electronic image processor with memory •Digital processor.•Miniature Milling machine.

Short comings:•Occlusal anatomy to be developed•Inaccuracies in fit•Poor esthetics

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-CEREC 2 : ( 1994) -They had better image processing systems .-it also has a cylindrical diamond stone which is able to finish off undercuts at buccal extensions -occlusal anatomy could be produced here

Disadvanatages- - has many parts ,so the operator had to move around -impression not good-marginal fit not good

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CEREC 3 :

•Different parts could be magnified in detail More finer details noted•Operator can record multiple images in seconds.•Creates a virtual cast for entire quadrant.•Additional step bur----enhances precision.

•Disadvantage: •not capable of producing margins of restoration

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CEREC 3-D•marginal fit good•contacts can be chosen •3 dimensionally movable camera

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3D cerec

Scanning and designing

3 dimensional viewing Milling

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PROCERA SYSTEM

Contact scanner

ANDERSON. M. & ODEN. ANobel Biocare + sandvik hard materialsPowder technology + cad/cam technology

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Ceramic Dental Implants

•Ceramic implants are white it has an obvious aesthetic advantage over titanium as it is indistinguishable from natural teeth.

•The high corrosion resistance of the material means that there is virtually no danger of corrosion with ceramic implants.

•Ceramic implants offer patients another more comfortable option.

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Are ceramic implants a viable alternative to titanium implants?

Clin Oral Implants Res. 2009 Sep;20 Suppl 4:32-47. Are ceramic implants a viable alternative to titanium implants? A systematic literature review. Andreiotelli M, Wenz HJ, Kohal RJ.

1. No difference was found in the rate of osseointegration between the different implant materials in animal experiments.

2. Alumina implants did not perform satisfactorily and therefore, based on this review, are not a viable alternative to titanium implants.

3. Zirconia, however, has the potential to be a successful implant material

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CLINICAL APPLICATION

CORRECT DIAGNOSIS

JUDGEMENT OF DENTIST

SKILLED LAB TECHNICIAN

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Use of In ceram alumina and In ceram Zirconia when

strength is required along

with opacity

Use of IPS Empress, All ceram when

higher translucency is

required asstrength is

lower

TWO DIRECTIONS TO GO IN….

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CONCLUSION

There are ample of ceramic materials available. Successful application of these materials will depend upon clinician’s ability to select appropriate material, manufacturing technique, and cementation or bonding procedures to match intraoral conditions and esthetic requirments.

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1.CONTEMPORARY FIXED PROSTHODONTICS -ROSENSTIEL2.PHILLIPS SCIENCE OF DENTAL MATERIALS -ANUSAVICE3.FUNDAMENTALS OF FIXED PROSTHODONTICS -SCHILLINGBURG4.CONTEMPORARY ESTHETIC DENTISTRY: -BRUCE J.CRISPIN5.ESTHETIC DENTISTRY: AN ARTISTS SCIENCE -RATNADEEP PATIL6.JPD 1996;75:18-32

7.JPD 2004;91:136-43

8.OPERATIVE DENTISTRY 1990;15:61-70

9.QUINT INT 1991;22:257-262

10.QUINT INT 2005;36:141-147

11.INT J PERIODONT REST DENT 1998;18:587-593

12.JOR 2005;32:180-187

13.JPD 2002;87:133-135

14.DENT MATER 2000;16:226-233

15.JPD 2000;83:530-534

16.QUINT INT 1985;3:135-141

17.JPD 1991;66:754-758

18.DENT MATER 2002;18:380-388

19.JPD 1991;66:747-753

20.J DENT 1990;18:227-235

REFERENCES

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