dental ceramics dental porcelain all-ceramic restorations dental material
DESCRIPTION
DENTAL CERAMICS Dental Porcelain All-CERAMIC RESTORATIONS dental materialTRANSCRIPT
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
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
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
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.
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)
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
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
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
Metal-ceramic restorations
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
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….)
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.
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
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.
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
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
All-CERAMIC RESTORATIONSAll-CERAMIC RESTORATIONS
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
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
1. Powder-slurry ceramics2. Castable ceramics3. Machinable ceramics4. Pressable ceramics5. Infiltrated galss ceramics
Families of all-ceramic Families of all-ceramic restorationsrestorations
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
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
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
CAD-CAM Technology
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
Copy-milling Technology
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
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