This document discusses ceramics and porcelain fused to metal restorations. It describes the composition and properties of dental ceramics and porcelains, including feldspathic and aluminous porcelains. The applications and parts of porcelain fused to metal restorations are outlined. The benefits and drawbacks of metal-ceramic restorations are summarized. Requirements for the metal coping and bonding of porcelain to the coping are also summarized.

1. Ceramics and PFM

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

3. DENTAL PORCELAIN
Dental Porcelain = an early type of dental
ceramics that has been modified to
improve its properties

4. APPLICATIONS OF PORCELAIN
1. Porcelain denture teeth
2. Porcelain jacket crown
3. Porcelain inlay

5.  4. Porcelain veneer
5. Porcelain fused to metal
prosthesis
6. Implant material

6. COMPOSITION OF DENTAL PORCELAIN
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
• Technically it is a glass rather than true porcelain
• They are translucent

7. COMPOSITION of DENTAL PORCELAIN
B. Aluminous porcelain
The 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.

8. Classification of Dental Porcelain
A. According to their fusion temperatures
1- 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 production
3 & 4 are used for crown and bridge construction
B. According to the method of their firing
1- Atmospheric firing
2- Vacuum firing (lower % of porosity)

9. PARTS OF PFM ( PORCELAIN FUSED TO METAL)
Core: cast metallic framework. Also known as coping.
Opaque porcelain : first layer consisting of porcelain modified with opacifying oxides
- Mask the darkness of the oxidized metal framework
- Metal-ceramic bond
Final buildup of dentine and enamel porcelain.

11. CHARACTERS OF 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 fracture toughness
• Hard, can cause wearing of opposing dentition

12. CHARACTERS OF DENTAL PORCELAIN (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

13. These restorations are composed of; Metal substructure (Coping)
supporting a ceramic veneer those are chemically and
mechanically-bonded together
Metal-Ceramic Restorations
Metal
substructure Opaque
porcelain
Body (dentine)
porcelain
Incisal (enamel)
porcelain

14. Benefits and drawbacks of the metal-ceramic restorations
Advantages:
1. Stronger than porcelain crowns
2. Can be used for constructing long-span bridges
3. Good esthetic and less liable to staining
4. High wear resistance
5. 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 area
3. Using opaque porcelain is essential to overcome the
metal color
4. Special properties of the metal coping are required for
proper results (see the next section….)

15. Requirements of the metal
coping1. 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.

16. Bonding of porcelain to the metal copings
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 layer
Irregularities

17. 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.

18. 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 Copings

19. Production of Metal copings
A. Casting of pure metals or metallic alloys
1- 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 die
1- 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

20. All-CERAMIC RESTORATIONS

21. Advantages of all-
ceramic restorations
 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

22. Disadvantages of all-ceramic restorations
 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

23. 1. Powder-slurry ceramics
2. Castable ceramics
3. Machinable ceramics
4. Pressable ceramics
5. Infiltrated galss ceramics
Families of all-ceramic restorations

24. 1. Powder-slurry ceramics
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 system

25. 2. 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 Apatite

26. 3. 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-mark II, (3) Dicor
MGC Blocks

27. CAD-CAM Technology

29. 3. 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) Cercon

30. Copy-milling Technology

31. 4. 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) Empress 2, (4) IPS

32. Uses for Metals:
 Substructure for PFM’s
 Full metallic crowns, bridges
 Inlays, onlays
 Substructure/framework for
partial dentures
 Temporary crowns (prefabricated)

33. Properties of Metals:
 Composed of metallic elements (80 pure metals)
 High thermal & electrical conductivity
 High ductility, opacity & luster
 High strength, high melting points
 Crystalline arrangement of atoms
 Various types of metals can be created by “alloying”
metals
 Mixing 2 or more metals
 Dental alloys must be resistant to corrosion

34. Forming Metal Objects:
 Metal is relatively stable when in a solid
state
 To mold metal, it must be heated beyond its
melting range
 Except the use of mercury in dental amalgam!
 When cooled, metal forms a crystalline solid
 Casting – heating metal and pouring it into a
mold where it solidifies into a specific shape
 A “lost-wax technique” is used to create the mold
space for the metal

36. ALLOYS:
 Alloys have advantages over pure metals alone:
 Stronger
 Harder
 Easier to fabricate
 Less expensive
 Alloys are formed when metallic atoms are
dissolved within the atoms and crystals of
another metal

37. Dental Alloy Requirements:
 Strong & hard enough to withstand occlusal forces
 Biologically compatible
 High resistance to corrosion & tarnish
 Easy to cast
 Inexpensive

38. Alloy Composition:
 Noble Metals – “Precious” Metals
 Gold (Au) *
 Platinum (Pt) *
 Palladium (Pd) *
 Iridium, Ruthenium, Niobium, Osmium
 Resistant to corrosion and tarnish
 Gold was the first metal successfully used
 copper & silver added to enhance it

39. Gold Alloys:
 Gold is a soft metal
 Less gold in alloy improves strength
 ADA-approved classes based on
properties of alloy
 Mixed with platinum, palladium,
copper & silver
 Gold alloys are expensive

40. Porcelain-Fused-to-Metal Alloys:
 Silver found to discolor porcelain
 Palladium added to alloy eliminates
discoloration and adds strength
 Base Metal Alloys – most popular for PFM’s
 Contain NO noble metals – “Non-Precious”
 Corrosion prevention by surface oxide layer
formed by Chromium content
 Primary metal is Nickel
 Allergen (10% women, 1% men)
 Carcinogen?
 Video