DENTAL CERAMICS Dental Porcelain All-CERAMIC RESTORATIONS dental material

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DENTAL CERAMICS DENTAL CERAMICS Generally Generally the word the word ceramic ceramic is used to name is used to name any material having both any material having both metallic metallic and and non- non- metallic metallic ions in its compositional formula ions in its compositional formula e.g. cements, gypsum, porcelain and glasses e.g. cements, gypsum, porcelain and glasses

description

DENTAL CERAMICS Dental Porcelain All-CERAMIC RESTORATIONS dental material

Transcript of DENTAL CERAMICS Dental Porcelain All-CERAMIC RESTORATIONS dental material

Page 1: DENTAL CERAMICS Dental Porcelain All-CERAMIC RESTORATIONS dental material

DENTAL CERAMICSDENTAL CERAMICS

GenerallyGenerally the word the word ceramicceramic is used to name any is used to name any material having both material having both metallicmetallic and and non-metallicnon-metallic ions in ions in

its compositional formulaits compositional formula

e.g. cements, gypsum, porcelain and glassese.g. cements, gypsum, porcelain and glasses

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DENTAL PORCELAINDENTAL PORCELAIN

Dental Porcelain = an early type of dental ceramics that has been modified

to improve its properties

APPLICATIONS OF PORCELAIN

1. Porcelain denture teeth2. Porcelain jacket crown3. Porcelain inlay4. Porcelain veneer5. Porcelain fused to metal prosthesis 6. Implant material

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COMPOSITION COMPOSITION OF OF DENTAL DENTAL PORCELAINPORCELAIN

A. Feldspathic porcelain

Fired material is composed of 1. Glassy phase (Vitreous matrix made of feldspars) Feldspars are mixture of Anhydrated alumino-silicates of both…. Potash feldspar = K2O. Al2O3. 6 SiO2 And .… Soda feldspar = Na2O. Al2O3. 6 SiO2

2. Dispersion of crystalline phase (mineral phase including silica and other oxides)

Main characters• Void of kaolin • Technically it is a glass rather than true porcelain• They are translucent

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COMPOSITION COMPOSITION DENTAL PORCELAINDENTAL PORCELAIN

B. Aluminous porcelainThe porcelain material contains 40-50% alumina crystals (Al2O3) in a low-fusing glass matrix.

High-Ceram – The dispersed alumina particles are much stronger

with higher modulus of elasticity and coefficient of thermal expansion than those of the glassy matrix.

– Presence of alumina makes the material opaque. (used only as coping beneath regular porcelain)

In-ceram alumina – It is not only a kind of infiltrated glass ceramic,

but also considered as one of the aluminous porcelains.

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Classification of Dental Classification of Dental PorcelainPorcelain

A. According to their fusion temperatures1- High-fusing (1300-1400oC)2- Medium-Fusing (1100-1300oC)3- Low-Fusing (850-1100oC)4- Ultra-Low- Fusing (< 850oC)

1 & 2 are used for denture teeth production3 & 4 are used for crown and bridge

construction

B. According to the method of their firing1- Atmospheric firing2- Vacuum firing (lower % of porosity)

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C. According to their clinical applications1. Core porcelain:

Used to form the basal layer of jacket crown2. Dentine or Body porcelain:

More translucent, used to build the body of crowns3. Enamel porcelain:

The most translucent, used to form the incisal edges

Classification of Dental Classification of Dental PorcelainsPorcelains

Manipulation Of Dental PorcelainManipulation Of Dental Porcelain

(Powder-slurry technique) (Powder-slurry technique) Watch the videoWatch the video

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CHARACTERS CHARACTERS OF DENTAL PORCELAINOF DENTAL PORCELAIN

1. Biological Properties:• Inert has no interaction with surrounding soft

tissue (biocompatible)

2. Interfacial Properties:• Not adhere chemically to dental cements

3. Chemical properties:

• Not soluble in oral fluids and resist acid attach• Both hydrofluoric acid and stannous fluoride

can cause an increase in surface roughness

4. Mechanical Properties:• Brittle • Low DTS and fracture toughness• Hard, can cause wearing of opposing dentition

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CHARACTERS CHARACTERS OF DENTAL PORCELAIN OF DENTAL PORCELAIN (Cont.D)(Cont.D)

5. Thermal Properties:• Low thermal diffusivity• Coefficient Of thermal expansion similar to that

of enamel and dentine

6. Esthetic properties:

• Excellent esthetic, and color matching• Difficult to be stained

7. Practicability:• Sensitive manipulation technique, Requiring

skilled operator and Special equipments• Firing shrinkage is always, So operator should

build up the restoration to a bigger size that allows shrinkage

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Metal-ceramic restorations

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These restorations are composed of; Metal substructure (Coping) supporting a ceramic

veneer those are chemically and mechanically-bonded together

Metal-Ceramic RestorationsMetal-Ceramic Restorations

Metal substructure Opaque

porcelain

Body (dentine) porcelain

Incisal (enamel) porcelain

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Benefits and drawbacks of the metal-Benefits and drawbacks of the metal-ceramic restorationsceramic restorations

Advantages:1. Stronger than porcelain crowns 2. Can be used for constructing long-span bridges3. Good esthetic and less liable to staining4. High wear resistance5. Long term clinical durability (2.3-7.5 years)6. Less preparation is required in comparison to all-

ceramic restorations

Disadvantages:1. Sufficient metal bulk (0.3 mm) is required for proper

rigidity 2. Metal display could result at the thin marginal area3. Using opaque porcelain is essential to overcome the

metal color4. Special properties of the metal coping are required for

proper results (see the next section….)

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Requirements of the metal Requirements of the metal copingcoping

1. Has melting temperature higher than the porcelain firing temp. (to avoid sagging at the time of porcelain firing)

2. Able to form an oxide layer that provides the chemical bond to porcelain (presence of indium or tin in high noble alloys is essential for that purpose. e.g gold alloys)

3. Has coefficient of thermal expansion a little bite higher than that of porcelain (to provide higher mechanical bond)

4. Has no greening effect on the porcelain color

5. High high elastic modulus (E) to resist the bending and the cracking of porcelain under masticatory force.

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Bonding of porcelain to the metal Bonding of porcelain to the metal copingscopings

1. Mechanical bonding: - Infiltration (flow) of the fused ceramic into the surface irregularities of the metal coping. - Sandblasting of the metal surface or using plastic beads during waxing are important for this issue.

Metal

Porcelain

Oxide layerIrregularities

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Bonding of porcelain to the metal Bonding of porcelain to the metal copingscopings

2. Chemical bonding: - Ionic bond between the metal oxide layer and the

opaque porcelain. - Metal degassing is important for oxide formation,

removing the surface contaminants and greases. - Thin oxide layer (in case of noble alloys) provides

stronger bond than the thick one (in case of base metal alloys).

3. Coeff. of thermal expansion mismatch: As a result of higher metal contraction on cooling , - The fused porcelain will be sucked (attracted) more

strongly into the metal surface irregularities.- Residual compressive stresses will developed in and

strengthen the porcelain.

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4. Application of a special bonding agent:Certain metal system (electro-forming) requires the application of specific bonding paste before building-up the porcelain.

Bonding of porcelain to the metal Bonding of porcelain to the metal CopingsCopings

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Production of Metal copingsProduction of Metal copings

A. Casting of pure metals or metallic alloys1- Commercially-pure titanium (CP Ti) 2- High gold alloy 3- Gold-palladium alloy 4- Palladium-silver alloy 5- High palladium alloys 6- Nickel- chromium alloy

B. Burnishing and heat treating metal foils on a die1- Platinum foil 2- Gold foil 3- Captek system

C. Electro-deposition of metal on a duplicate die

D. CAD-CAM processing of a metal ingot

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All-CERAMIC RESTORATIONSAll-CERAMIC RESTORATIONS

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Advantages of Advantages of all-ceramic all-ceramic restorationsrestorations

Biocompatibility Superior esthetic (No metal display) Good bonding (cohesion) between the ceramic

coping and the porcelain veneer Acceptable mechanical properties Superior hardness that provides the restoration

its wear resistance Resist the degradation in oral fluids Low thermal diffusivity Most systems could be used for constructing

inlays, onlays and crowns

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Disadvantages of all-ceramic Disadvantages of all-ceramic restorationsrestorations

High cost of the materials and the processing equipments

Excessive tooth reduction is needed

Most systems utilize feld-spathic porcelain coating to provide the desired color and contour

Most systems are not suitable to construct long span bridge

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1. Powder-slurry ceramics2. Castable ceramics3. Machinable ceramics4. Pressable ceramics5. Infiltrated galss ceramics

Families of all-ceramic Families of all-ceramic restorationsrestorations

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1.1. Powder-slurry Powder-slurry ceramicsceramics

The material presents as powder to be mixed with liquid forming a slurry that is

used to build the restoration up

e.g. (1) Optec HSP, (2) Duceram systeme.g. (1) Optec HSP, (2) Duceram system

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2. Castable ceramics2. Castable ceramics

Ceramic ingot is fused and cast in a refractory (investment) mold

made by the lost wax technique

e.g. (1) Dicor, (2) Dicor Plus, (3) Castable Apatitee.g. (1) Dicor, (2) Dicor Plus, (3) Castable Apatite

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3. Machinable ceramics3. Machinable ceramics

CAD- CAM technology

The prepared tooth is optically impressed (pictured using intra-oral camera). The restoration is design over that image by the aid of computer……Then

Ceramic blocks are carved into restorations by the aid of computer-controlled milling machine

e.g. (1) Cerec Vitablocks-mark I, (2) Cerec Vitablocks-e.g. (1) Cerec Vitablocks-mark I, (2) Cerec Vitablocks-mark II, (3) Dicor MGC Blocksmark II, (3) Dicor MGC Blocks

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CAD-CAM Technology

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3. Machinable ceramics3. Machinable ceramics

Copy-Milling technology

The prepared tooth is impressed poured in gypsum to form a die.

A wax pattern is built over the die……Then Ceramic blocks are carved into restorations by the aid of computer-controlled milling machine that is

guided by the constructed wax patter

e.g. (1) Celay blocks (2) Lava Zerconia, (3) Cercone.g. (1) Celay blocks (2) Lava Zerconia, (3) Cercon

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Copy-milling Technology

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4. Pressable ceramics4. Pressable ceramics

Ceramic ingots are softened by heat and pressed into a refractory mold

using special alumina injector

e.g. (1) Optec Pressable Glass Ceramic, (2) IPS Empress ,(3) e.g. (1) Optec Pressable Glass Ceramic, (2) IPS Empress ,(3) Empress 2, (4) IPS e.max pressEmpress 2, (4) IPS e.max press

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5. Infiltrated glass 5. Infiltrated glass ceramicsceramics

A porous crystalline slip is formed by fusion of

Metallic particles at high temperature.

A Glass coat is then fused over the porous slip to infiltrate into the pores

and strengthen the structure.

Veneering porcelain is then required to provide the desired shade and

contoure.g.(1) In-Ceram Alumina, (2) In-Ceram Spinel, (3) In-Ceram e.g.(1) In-Ceram Alumina, (2) In-Ceram Spinel, (3) In-Ceram

ZerconiaZerconia