This document provides a detailed history and overview of dental ceramics. It discusses the origins and composition of different types of ceramics used in dentistry like feldspathic porcelain, leucite-reinforced porcelain, and aluminous porcelain. The document also outlines the various methods used to classify and fabricate dental ceramics, including processes like condensation and sintering, casting and ceramming, machining, pressure molding, and glass infiltration. Key developments in the history of using ceramics in dentistry are highlighted from the 1700s to present day.

1. Dental Ceramics
1

2.  Ceramic is derived from the Greek word “keramikos” -‘earthen’.
 Ceramic is derived from Sanskrit word meaning burnt earth.
Introduction
2
 Although many advances have been made in composites and
glass ionomers, ceramic material holds a special place in dentistry.
 Its color, translucency and vitality cannot be matched by any
material.

3.  Compounds of one or more metals with a non metallic element that
may be used as a single structural component or as one of the
several layers that are used in the fabrication of a ceramic based
prosthesis . (GPT- 7)
Ceramics
3
 are composed of essentially the same materials, the principle
difference being in the proportion of the primary ingredients (such as
feldspar, silica and kaolin/ clay) and firing procedures (temperature,
method etc).
 All porcelains are ceramics, but not all ceramics are porcelains.
Porcelain

4. 4

5.  History of porcelain used as a dental material goes back nearly 250
years.
 1728 - the use of porcelain in dentistry was first mentioned by Pirre
Fauchard.
 1774 – Alexis Duchateau, with the assistance of a Parisian dentist
Nicholas Dubois de Chemant, made the first successful porcelain
dentures replacing the stained and malodorous ivory prostheses of
Duchateau
History……..
5

6.  1806 to1808 - Fonzi an Italian dentist introduced the first porcelain
teeth that contained embedded platinum pins. But they never met with
great approval because of their brittleness and opacity. He also used
metal oxides to produce 26 shades of color in porcelain.
 1825- Samuel Stockton began fabrication of fused porcelain teeth in
Philadelphia. His initials were represented in the name of the S.S.White
company.
 1837 – John Murphy of London introduced the plantium foil technique
History……..
6

7.  1884 – Dr Charles H.Land pioneered the development of the first glass
furnace for fusing porcelain.
 1887 – Dr C.H.Land of Detroit developed the first porcelain jacket crown
(PJC) using the Platinum Foil Matrix technique.
 1894 – Levitt Ellsworth Custer developed the first electric furnace for
porcelain.
 1903 - Dr.Charles Land introduced first ceramic crowns to dentistry.
History……..
7

8.  1910 – High fusing electric furnaces (fusion at 20000 F) were
recommended to minimize the firing shrinkage and application of
hydrofluoric acid to the fitting surface to produce a ‘honeycomb’
appearance to enhance retention.
 1923 - Wain - inlays and onlays using dental porcelain.
 1940 - with advent of acrylics PJC lost popularity.
 1957 – S. D. Stookey invented glass-ceramic.
History……..
8

9. History……..
 1958 - Vines et al, introduced finer porcelain powders for vacuum
firing. It was the first major improvement in the esthetics, because
it increased the translucency of all-porcelain crowns.
9
 1962- Weinstein et al patented formulations of feldspathic porcelain
and alloys that bonded chemically & were thermally compatible
with feldspathic porcelains.
 1963 - first commercial porcelain developed by Vita Zahnfabrik.

10. History……..
10
 1965- McLean & Hughes introduced dental aluminous core ceramic
with significant improvement in fracture resistance.
 1968 – W.T. MacCulloch fabricated denture teeth from a glass-
ceramic. He suggested the possibility of using glass-ceramics in
inlays and crowns.
 1976 – McLean & Sced developed the platinum bonded alumina
crown. The attachment of aluminous porcelain to the platinum was
achieved by surface coating of the metal with a thin layer of tin.

11.  1983 – Sozio & Riley first described shrink-free ceramics (marketed as
Cerestore), which was followed by development of injection-molded
castable glass-ceramic by the University of Zurich (marketed as IPS
Empress).
 1984- Adair & Grossman introduced Dicor glass-ceramic.
 1985 – First CAD/CAM crown was publically milled and installed in the
mouth
 1986 – The first generation CEREC 1 (Siemens) CAD/CAM system was
introduced.
History……..
11

12.  1988 – Michael Sadoun first introduced In-ceram, a glass-infiltrated
aluminous porcelain.
 1989 – The concept of all-ceramic post & core was introduced using
Dicor glass-ceramic initially, followed by In-cream, IPS Empress and
Zirconica ceramics.
History……..
12
 1993 – The Procera CAD/CAM system was developed by Andersson
M. & Oden by a co- operative effort between Nobel Biocare and
Sandvik.

13.  1994 – The second generation CEREC 2 (Siemens/Sirona)
CAD/CAM system was presented.
 Late 1990’s – IPS Empress 2, a second generation pressable
ceramic made from lithium-disilicate frame work with an apatite
layered ceramic was introduced
 1999 – IPS SIGN (Ivoclar AG), a feldspar-free fluorapatite glass
ceramic system for use in metal-ceramics was presented.
History……..
13

14. History……..
 2000 – two dimensional CEREC 3 was presented.
 2002 - Lava uses a laser optical system to digitize information from
multiple abutment margins
14
 2005 – The three dimensional CEREC 3D was presented.
Scanning and designing 3 dimensional viewing Milling

15. According to Type
1. Feldspathic porcelain
2. Leucite-reinforced porcelain
3. Aluminous porcelain
4. Alumina
5. Glass-infiltrated alumina
6. Glass-infiltrated spinel
7. Glass-ceramic.
According to Processing Method
1. Sintering
2. Casting
3. Machining
K.J. Anusavice, 1996, Phillips 10th edition)
Classification of Dental Ceramics
15

16. According to Use or Indications
Denture teeth, inlay, onlay, Ceramic brackets for orthodontic treatment.
Classification……
Anterior Crowns Posterior Crowns
Veneers
Fixed Partial Dentures
Post & cores
16

17. According to Substructure Material
1. Cast metal
2. Swaged metal
3. Glass-ceramic
4. CAD-CAM porcelain
5. Sintered ceramic core.
(By K.J. Anusavice, 1996, Phillips 10th edition).
17

18. 1. Air fired.
2. Vacuum fired
According to Method of Firing
1. Ultra low fusing (<850oC)
2. Low fusing (850oC -1100oC)
3. Medium fusing (1100oC -1300oC)
4. High fusing (>1300oC)
According to Firing Temperature
1. Non-Crystalline Ceramics e.g.: Feldspathic porcelain
2. Crystalline Ceramics e.g.: Aluminous porcelain,
Glass-Ceramics
According to Microstructure
18

19. 1. Core porcelain
2. Opaque porcelain
3. Body (dentin) porcelain
4. Gingival, cervical or neck porcelain
5. Enamel (incisal) porcelain
6. Color frits (pigments)
7. Glazed porcelains
According to Varieties Used/ Application
Classification……
19

20. Classification……
According to method of fabrication
-(Marc Rosenblum & Alan Schulman JADA March 1997).
 Cast metal systems : eg: Vita Metall Keramik (VMK 95)
 Non- Cast Metal Systems Foil Crown Systems /All –
Ceramic Systems
1. Conventional Powder – Slurry Ceramics
2. Castable Ceramics
3. Machinable Ceramics
4. Pressable Ceramics
5. Infiltrated Ceramics
20

21. 1.Conventional Powder – Slurry Ceramics
condensing & sintering.
1. Alumina reinforced Porcelain e.g. Hi-Ceram
2. Magnesia reinforced Porcelain e.g. Magnesia cores
3. Leucite reinforced (High strength porcelain)
e.g. Optec HSP
4. Zirconia whisker – fiber reinforced e.g. Mirage II
5. Low fusing ceramics
21

22. 2. Castable Ceramics
casting & ceramming
1. Flouromicas e.g. Dicor
2. Apatite based Glass-Ceramics e.g. Cera Pearl
3. Other Glass-Ceramics e.g. Lithia based, Calcium
phosphate based
22

23. 3. Machinable Ceramics
Milling & machining
Analogous Systems
Grinding techniques :
a) Mechanical e.g. : Celay
b) Automatic e.g. Ceramatic II. DCP
Erosive techniques:
a) Sono-erosion e.g. Erosonic
b) Spark-erosion e.g. Procera
Digital systems (CAD / CAM):
Direct e.g. Cerec 1 & Cerec 2
Indirect e.g. Cicero, Denti CAD
23

24. 4. Pressable Ceramics
pressure molding & sintering
1. Shrink-Free Alumina Reinforced Ceramic (Injection Molded)
E.g. Cerestore / Alceram
2. Leucite Reinforced Ceramic (Heat – Transfer Molded)
E.g. IPS Empress, IPS Empress 2, Optec OPC.
24

25. 5. Infiltrated Ceramics
slip-casting, sintering & glass infiltration
1) Alumina based
e.g. In-Ceram Alumina
2) Spinel based
e.g. In-Ceram Spinel
3) Zirconia based
e.g. In-Ceram Zirconia
25

26. Ingredients Wt % Function
Feldspar 60-80 Basic glass former
Alumina 8-20 Strengthener, glass former, opacifier
Kaolin 3-5 Binder during firing
Quartz (crystalline silica) 15-20 Filler
Boric oxide 2-7 Glass modifiers, flux
Oxides of Na, K, Ca 9-15 Glass modifiers, interrupter, fluxes
Metallic pigments <1% Color matching
Oxides of Zr, Sn, Ba, Ti, B Trace As color pigments & shade
Composition of Dental Ceramics
26

27. Feldspar
 These are a group of naturally occurring minerals, which are complex
alkali aluminium silicate.
Types of feldspar:
 Soda feldspar – Sodium alumina ( Na2O Al2O3, 2SiO2, 2H2O)
decreases fusion temperature
 Potash feldspar – Potassium aluminium silicate ( K2O, Al2O3, 6SiO2)
increases the viscosity of glass.
Composition …..
27
 Proper potash content decreases the danger of excessive pyroplastic
flow during firing of porcelain, which could otherwise result in rounding of
the edges, loss of form ,shape; and the obliteration of surface
characteristics which contribute to a life like appearance.

28. Role of feldspar
 Glass phase formation:
During firing, the feldspar fuses and forms a glassy phase that softens
and flows slightly allowing the porcelain powder particles to coalesce
together, thus acts as a matrix and binds silica and kaolin.
Composition …..
28
It is a basic glass former
Leucite formation
 Between 1150o & 1530oc it undergoes incongruent melting and forms
crystals of leucite.
 Leucite is a potassium aluminum silicate with large coefficient of
thermal expansion

29. Function of Leucite
 To raise the coefficient of thermal expansion of porcelain and bring it
closer to that of the metal substrate; consequently increasing the
hardness and fusion temperature.
 Strengthening of porcelain
e.g. Optec HSP, Cerinate, & IPS Empress.
29
Composition …..

30.  Increases the mouldability of the plastic porcelain
 Acts as a binder and helps in maintaining the shape of the unfired
porcelain during firing.
 At high temperature, it fuses and reacts with other ingredients to
form the glassy matrix.
Composition …..
Kaolin
30
Hydrated aluminum silicate.
 Opacity even when present in very small quantities.
Drawback

31.  It is basically a glass consisting of 3-dimensional network of silica with
a very high fusion temperature.
Composition …..
Quartz (Crystalline Silica)
31
 Acts as a filler
 Provides strength and hardness to porcelain.
 Because it has a high melting point, it maintains the form (shape) of
a freestanding object during firing.
Functions

32. Glass Modifiers or Fluxes
 Can be defined as elements that interfere with the integrity of the
SiO2 (glass) network and alter their three-dimensional state.
 Purpose
 To lower the fusion temperature of a glass by reducing the amount
of cross-linking between the oxygen and glass forming elements.
 Increase the flow of porcelain during firing.
Composition …..
32
e.g. Alkali metal ions such as Na, K or Ca (usually as carbonates).
If concentration is too high:
 It reduces chemical durability of the glass. (resistance to attack
by water, acids and alkalis)
 It causes the glass to crystallize or devitrify.

33. Alumina (Aluminum oxide)
 One of the hardest and strongest oxides of aluminium
 Increases viscosity of porcelain during firing.
 Gives strength and opacity to the material.
33
Boric Oxide
 Boric Oxide (B2 O3) although a powerful flux (glass modifier), it can
also act as a glass former and form its own glass network, producing
Boron Glasses.
 12%- above which the less stable form BO3 takes over.

34. Water
 Water is an important glass modifier.
 The hydronium ion, H3O can replace Na or other metal ions in a
ceramic that contains glass modifiers.
Significance
 This replacement is responsible for the phenomenon of “slow crack
growth” of ceramics that are exposed to tensile stresses and stored in
moist environment
Composition …..
34

35. Coloring Agents
 Dental porcelains colored by the addition of concentrated color frits
(generally metallic oxides) into the basic glass.
 The glass thus obtained will be highly color saturated and when
ground to a fine powder, can be used in small amounts to modify the
uncolored porcelain powder.
Composition …..
35
 Pink- Chromium or chrome-aluminia
 Yellow – indium
 Blue- Cobalt salts in the form of oxide are useful in developing of the
enamel shades
 Grey- Iron oxide (black) or platinum Grey: used for producing enamels
or grayer section of the dentin colors, and also for an effect of
translucency.

36.  Green- Chromium oxide: is generally avoided since green is the
characteristic color of glass.
Other pigments used may be –
 Titanium oxide –yellow brown,
 manganese oxide- lavender,
 iron/nickel oxide- brown,
 copper oxide – green.
Composition …..
36

37. Opacifying Agents
 Reduces the translucency of porcelain
 Produces dentin colors in particular, which requires greater opacity
than that of enamel colors.
The common metallic oxides used are –
 Cerium oxide, Titanium oxide,Tin oxide, and
 Zirconium oxide (ZrO2)- most popularly used opacifying agent.
37
consists of a metal oxide.

38. Mode of Supply
Porcelain kit consists of:
 Fine ceramic powders of different shades of enamel, dentin,
core/opaque
 Special liquid/ distilled water- vehicle/medium for ceramic powder
(binder)
 Stains or color modifiers
 Glazes
38
Various enamel, dentin and opaquer porcelains

39. Methods of fabricating ceramic restorations
 Condensing and Sintering,
 Casting & Ceramming
 Milling (Machining) by mechanical and digital systems.
 Pressure molding & Sintering
 Slip casting, Sintering & Glass infiltration
39

40.  Condensation
 Sintering
 Glazing
 Cooling.
Fabrication of Porcelain
40
However, fabrication of a conventional porcelain restoration is
basically composed of the following stages:

41. Mixing of powder and liquid
41

42. Condensation
 Process of packing the powder particles together & removing
excess water is known as condensation.
 Porcelain powder particles within the mass are closely packed in
order to reduce volume shrinkage of porcelain & minimize porosity
in the fired porcelain.
 Porcelain should not dry out as the porcelain is held together due
to surface tension.
42

43. 1. Spatulation
2. Brush technique
3. Vibration
4. Ultrasonic
Condensation…………
Methods of condensation
43
Condensation of porcelain slurry on
a metal framework

44.  Article is carefully smoothened with a spatula when extra water from
inside comes to the surface by capillary action which is removed by
blotting paper or linen cloth.
44
Condensation…………
Spatulation
 This method employs the addition of dry porcelain powder on the
surface by a brush to the side opposite of wet porcelain to absorb the
moisture.
 As the water is drawn towards the dry powder, the wet particles are
pulled together.
Brush technique

45.  This method used mild vibration to pack the wet powder densely on
the underlying framework.
 The excess water is blotted away with a clean tissue
 An electrically operated brush called the Vibra Brush can also be
used in this technique, which although very efficient, lacks the
flexibility offered by the light weight hand held sable brush.
45
Condensation…………
Vibration Method
Ultrasonic method
 Ultrasonic vibrations are transmitted electrically & water coming
out is removed using blotting paper or linen cloth.

46. Sintering
 The process of fusing the condensed mass is known as firing/
sintering.
 Porcelain firing unit (muffle chamber) is preheated to 650oC &
article to be fired is placed in a fire clay tray & then placed on a
platform.
 Preheating the porcelain by placing it in front of the muffle is
essential. Direct heating causes rapid steam production that breaks
up the mass.
46

47.  Platform is raised & article is held inside
muffle chamber for 5 min. (remaining water
is converted into steam & comes out).
 Door of muffle chamber is closed &
evacuated by connecting it to a vacuum
pump.
 Temperature is gradually raised to firing
temperature of porcelain.
Muffle Chamber
47
Firing procedure………

48.  Shrinks 30-40% by volume.
 During firing there is partial fusion of particles at their point of
contact. As the temperature is raised the fused glass gradually
flows to fill up air spaces.
 Vacuum firing is done to reduce porosity in porcelain.
48

49. Stages of Maturity
Stages are known as bisque/biscuit stages.
Different stages are:
 Low bisque stage
 Medium bisque stage
 High bisque stage.
 Less the number of firings, higher is the strength and better is
the esthetics.
Firing procedure………
49

50.  As temperature rises, surface of the particles begin to soften &
these loose particles just begin to join.
 No volume shrinkage.
 If firing is stopped at this stage, particles form a porous mass.
 Weak & friable
 Opaque
 Used in glass infiltrated ceramics- Inceram
50
Firing procedure………
Low Bisque Stage

51.  On further heating, more softening of particles takes place & they
begin to melt.
 Better cohesion.
 Slight volume shrinkage.
 Reduced although still porous
 Moderate strength
 Less opaque and color has developed
51
Firing procedure………
Medium Bisque Stage

52.  Further heating causes melting of all particles producing complete
cohesion & maximum volume shrinkage.
 Porosity absent
 High Strength
 Relatively smooth surface with a light sheen
 Color & translucency developed
52
Firing procedure………
High Bisque Stage
 As liquid is highly viscous, it retains its shape for some time
 If heating is prolonged, liquid gradually flows under gravity i.e.
pyroplastic flow, & article looses sharp corners & its shape.
 Firing is discontinued usually at this stage for complete melting.

53. Glazes
 Colorless porcelain applied to the surface to give it a glossy lifelike
appearance.
 Does not contain opacifiers.
 Low fusion temperature.
 Contain lot of glass modifiers.
53
Glazing
 To remove surface cracks & improve the flexure strength
Two types :
 Auto glazing or Self glazing
 Over glazing

54.  Auto glazing or Self glazing
Temperature of porcelain is quickly raised to melt surface particles
which flow & fill all the microcracks.
 Over glazing
A thin layer of transparent glaze porcelain of lower fusion temperature
is coated on body porcelain & is then fired at lower temperature only to
melt outer layer of glaze porcelain which flows into surface cracks.
54
Glazing……

55. Cooling of the fired article
 Muffle chamber is gradually cooled according to manufacturer
instructions for porcelain to undergo uniform shrinkage to minimize
formation of micro cracks
 Platform is then brought down & the article is removed.
55
 Surface microcracks can be filled by the application of Glaze

56.  Excellent esthetic properties :: suitable stains can be applied ::
color parameters (hue, chroma & value) are permanent.
 Color stability
 Chemically inert, excellent biocompatibility
 Chemical stability: insoluble and impermeable to oral fluids,
chemical degradation by fluoride attack.
56
Properties

57.  Low coefficient of thermal expansion, nearly same as tooth enamel
6.4 -7.8 x 10-6/oc.
 Dimensional stability: stable after firing
 Low thermal conductivity
 Compressive strength: good 480 MPA.
 Greater surface hardness (460 KHN) than tooth enamel (343 KHN)
: abrasion & wearing of opposing natural tooth and metal
restorations
57
Properties

58.  Brittle
 Tensile strength - 35-50 MPA
 Modulus of elasticity: low 40 GPa
 Shear strength: low 110 MPa.
 Shrinkage
 Volumetric - 35 – 45 %, Linear - 11 – 14 %
 Minimized by using lesser binder, proper condensation, build – up of
restoration 1/3rd larger than original size and firing in successive
stages.
58
Properties

59. Griffiths Flaw
Crack Growth
Sintering Process
Why are Ceramics weak ?
On moisture exposure crack growth is accelerated
1. Brittle – Covalent bonds
2. Inherent flaws
3. > # in moist environment
59
D.W. Jones- 1983

60. In ceramics, micro cracks are caused by
 The condensation, melting and sintering process.
 The high contact angle of ceramics on metal.
 Differences in the coefficient of thermal expansion between alloy or
core and veneers.
 Grinding and abrasion.
 Tensile stresses during function.
60

61. Methods
to
Strengthen Porcelain
61

62. 62
1. Methods of Strengthening brittle materials
2. Methods of designing components to minimize
stress concentrations and tensile stresses
According to K. J. Anusavice
(Phillip’s Science of D Materials, 1996)

63. A. Methods of strengthening brittle materials
1.Ion exchange
2.Thermal tempering
3.Thermal compatibility
B) Methods of designing components to minimize stress
concentrations and tensile stresses
1. Reducing stress raisers
2. Minimize tensile stresses
Residual compressive
stresses
Interruption of crack
propagation
Transformation
toughening
Particle stabilized
zirconia
Dispersion
of crystalline
phase
Al, dicor
63

64.  This is one of the widely used methods of strengthening glasses and
ceramics.
 Strengthening is gained by the fact that, residual stresses must first
be negated by developing tensile stresses before any net tensile
stress develops.
64
Development of Residual Compressive Stresses
A. Methods of strengthening brittle materials

65.  Smaller Na+ ions are exchanged by K+ ion which are 35% bigger.
 This replacement by ion exchange introduces large residual
compressive stresses (roughly 700mpa/1,00,000 psi).
 Squeezing of K into a smaller space, termed as stuffing.
 Soda feldspathic porcelain is kept immersed in molten KNO3 solution
for 20-30 min.
65
Development of residual compressive stresses………..
Ion exchange or chemical tempering
 Alumina reinforced materials, Dicor glass-ceramic core and some
conventional feldspathic porcelains with high potash feldspar content.
Limitation

66.  It creates residual compressive stresses by rapidly cooling
(quenching) the surface of the object while it is still hot, and in the
molten state.
 This rapid cooling produces a skin of rigid glass surrounding a
molten core.
 As the molten core solidifies, it shrinks, creating residual
compressive stresses within the outer surface.
66
Development of residual compressive stresses………..
Thermal tempering

67.  This method is used to strengthen glasses used for automobile
windows and windshield, sliding glass doors and diving masks.
 For dental applications, it is more effective to quench hot glass-
phase ceramics in silicone oil or other special liquids rather than
using air jets that may not uniformly cool
67
Development of residual compressive stresses………..
Thermal tempering

68.  Veneering ceramic with two or more layers of ceramic
compositions having slightly different coefficient of thermal
expansions; one layer contracting slightly more than other layers
thus inducing residual compressive stresses.
 eg. Inceram, Metal-ceramic restorations
 On cooling metal contracts more than ceramic, thus leaving the
outer layer of ceramic in residual compressive stresses
68
Development of residual compressive stresses………..
Thermal compatibility /
Thermal expansion coefficient mismatching

69.  This method involves strengthening glasses and
ceramics by reinforcing them with a dispersed phase
of a different material that is capable of hindering a
crack from propagating through the material.
69
Interruption of crack propagation
A. Methods of strengthening brittle materials

70.  Tough crystalline material like alumina, leucite, lithia disilicate,
magnesia is added in particulate form.
 Crack cannot propagate through alumina as easily as it propagates in
the glass.
 E.g. Dicor
 Coefficient of thermal expansion between the particle and glass
requires a close match.
Interruption of crack propagation……
70
Dispersion of crystalline phase

71.  A crystalline material that is capable of undergoing a change of
crystal structure when placed under stress is incorporated.
 E.g. partially stabilized zirconia which, at lower temperature,
transforms into more stable & harder monoclinic phase with an
increase in volume
 Refractive index of PSZ is higher than glass.
71
Transformation toughening
Interruption of crack propagation……

72. Reducing Stress Raisers
 Stress Raisers are discontinuities in ceramic structures that
cause stress concentration.
E.g. Abrupt changes in shape or thickness in the ceramic, renders the
restoration more prone to failure
 Creases or folds of the Platinum foil substrate in PJC, become
embedded in the porcelain and leave behind notches (stress
raisers).
72
B. Methods of designing components to minimize stress
concentrations and tensile stresses

73. Minimizing Tensile Stress
 In Metal-Ceramic Crowns -
 The strong, yet ductile metal coping minimizes flexure of the porcelain
structure in an attempt to overcome the associated tensile stress.
 Both, the Bonded Platinum foil technique and the Swaged Alloy foil
technique are also based on this same concept.
73
 Favorable occlusion in PJC helps to avoid tensile stress.
B. Methods of designing components to minimize stress
concentrations and tensile stresses

74. Esthetic Properties of Dental Ceramics
 The principal reason for the choice of porcelain as a restorative
material is its esthetic qualities in matching the adjacent tooth
structure in translucency, color and chroma.
74

75. Color production in natural teeth
E Incident = E Scattered + E Reflected + E Absorbed +E Transmitted
+E Fluoresced
75

76. 76
Incisal third Middle third Cervical/gingival third
Enamel covering with
little or no dentin
underneath produces a
wrap around effect
which results in
increased translucency
in the incisal third and
approximal areas.
This region consists
predominantly of dentin,
hence the overlying
enamel takes on some
of the dentinal hue
(yellow-orange) which is
modified by the
translucent blue grey
enamel resulting in a
composite colour.
Enamel thins down
towards the cervical line,
hence the underlying
dentinal hue results in a
deep hue ranging from
orange-yellow to often a
distinct brown depending
on the degree of
calcification of dentin.
Variations of Tooth Color

77.  Dental porcelains are pigmented by the inclusion of oxides to
provide desired shades.
 Specimens of each shade (collectively called a shade guide).
Shade Guide
77
photo
Disadvantages in using shade guides
 Tabs are much thicker
 Tabs are more translucent than teeth
 The necks of the shade tabs are made from a deeper hue and this
region tends to distract the observers matching ability in the gingival
third of the tab

78. Shade Matching Guidelines
 Remove all lipstick, heavy make-up, or large jewelry
 Use cool, color-corrected fluorescent lighting or sunlight near the
window (during middle portion of the day )
 If eyes seem fatigued to yellow, look at a blue napkin or blue wall to
desensitize the eyes
 Select basic hue of tooth by matching the shade of patient’s canine
(most highly chromatic tooth)
 Color matching should be done under two or more different light
sources
78

79. Metal Ceramics
 Most widely used prosthesis system in fixed prosthodontics
 Mechanical properties Esthetic properties
 Metal Ceramic
79

80. Cross section of metal-ceramic crown
80
Parts of Ceramic Crown

81. Technical procedures in Metal –ceramic restorations
 Casting
 Heat degassing treatment
 Finishing
 Sandblasting
 Condensation of porcelain
81

82.  Both the metal and ceramics must have coefficients of thermal
contraction that are closely matched such that the metal has a
slightly higher value.
 High proportional limit, high modulus of elasticity (to reduce stress
on the porcelain)
 High fusion temperature (more than porcelain)
 Should exhibit minimal creep during firing of the porcelain
82
Ideal Requirements for Metals & Ceramic

83.  Possess adequate mechanical strength for multiple splinting and
bridge work.
 The surface metal oxide should not discolor the porcelain or
interfere with glass formation.
 Biocompatible
 Chemically stable (high corrosion resistance)
 Ability to wet & bond metal surface
83
Ideal Requirements for Metals & Ceramic

84. 84
• High Noble alloys
• Noble alloys
• Base-metal alloys
Types of Metal Ceramic Systems
Cast metal ceramic alloys
Foil Copings
 Bonded platinum foil coping
 Swaged gold foil coping

85. High Noble alloys
 Metal-ceramic alloys containing > 40 wt% gold and at least 60 wt%
of noble metals (Gold, Platinum and palladium and/or the other
noble metals)
 Platinum - hardens the gold
 Palladium - lowers the coefficient of thermal expansion
 Melting temperature : 1000oC-1150oC.
85

86. Noble alloys
 According to the ADA classification of 1984,noble alloys contain at
least 25 wt% of the noble metals, but not necessarily contain any
gold.
 Pd reduces tarnishing effect of Ag & Cu.
 Melting temperature : 1000oC-1250oC.
86
 Cr or Ti alloys : Ni-Cr-Mo-Be, Ni-Cr-Mo, Co-Cr-Mo, Ti-Al-V.
 Superior mechanical properties.
 Melting temperature : 1300oC or more.
Base-metal alloys

87. Advantages of Base Metal Alloys
 Higher hardness and elastic modulus (stiffness) values, permit the
fabrication of thinner copings (upto 0.1mm) and thus its use in long
span FPD’s.
 More sag - resistant at elevated temperatures.
 Substantial cost difference between base - metal and noble metal
alloys. The intrinsic value of the component elements is significantly
lesser than that of noble-metal alloys.
87

88. Limiting Features
 Higher solidification shrinkage requires special compensatory
procedures to obtain acceptable fitting.
 Potential for porcelain delamination due to separation of poorly adherent
oxide layer from the metal substrate.
 Potential toxicity of Beryllium and allergic potential of Nickel.
88
 Poor resistance to tarnish and corrosion of nickel containing alloys.
 Chair side-grinding and polishing requires more chair-side time and the
use of high-speed equipment due to the high hardness/strength.

89. Non - Cast Metal - Ceramic Systems
 Non-Cast Metal-Ceramic Systems are an advancement in the
fabrication of metal-ceramic restorations, which permits the
fabrication of a metal-ceramic restoration without waxing, investing or
casting.
 It was introduced by Dr. Itzhak Shoher and Aaron Whiteman.
89

90.  Bonding aluminous porcelain to platinum foil.
 Platinum foil is electroplated with tin & then oxidized in a furnace
(degassing)
 Thicker cast metal coping is replaced by thinner platinum foil ::
allowing more space for porcelain :: improved esthetics
90
Bonded Platinum Foil Coping

91.  Use of a golden foil is intended to warm the color of the crown and
facilitate tooth color (Yellowish tinge).
 Laminated swaged gold alloy foil supplied in fluted shape
 Foil is swaged onto die & flame sintered to form a coping
 “Interfacial alloy” powder is applied & fired, & the coping is then
veneered with porcelain
91
Swaged Gold Foil Coping
Renaissance type
Burnishing the margin
Flame sintering

92. Captek System
 Bonding to porcelain is achieved by the formation of an intermediate
layer of material such as Capbond metal-ceramic ‘bonder’.
 Two strips of highly malleable metal powder impregnated ‘wax’ are
adapted to a refractory die.
 The first strip contains a gold, platinum and palladium alloy and the
second is impregnated with all-gold.
92

93. Captek System
 The first strip is fired onto a refractory die at 10750 C for 11mins
producing a rigid porous layer.
 Application and firing of the second strip is said to result in capillary
infiltration of the spongiform network by the molten gold, resulting
in a metal alloy framework with density similar to that of
conventional castings.
93

94.  Development of a durable bond and the thermal compatibility
between the porcelain and the alloy are the primary requirements
for the success of a metal - ceramic restoration.
94
Metal-Ceramic Bonding
Metal-Ceramic Bonding Techniques
 Mechanical
 Chemical

95. Mechanical Method
 Bonding surface of cast metal is made rough using diamond &
carbide burs, or sandblasting (with pure alumina).
 This results in increased surface area.
 Mechanical interlocking
 Pd – Ag alloys form no external oxides- hence mechanical bonding
95

96.  Primary bonding mechanism
 Presence of adherent oxide layer is essential for good bond formation
 In precious metals, tin oxide and iridium oxide are responsible for bond
formation
 In base metals, chromium oxide forms the bond.
 For a good bond, metal substructure should be free of contamination
 Metal is oxidized in a furnace at 950oC for 5 min.
Chemical Method
96

97.  Ceramic bonding on to metals by electrodeposition of metal castings
and heating to form suitable metal oxides.
 Alloy coping is electrodeposited with a layer of pure gold & a
subsequent short “flashing” deposition of tin
 Used with Co-Cr, Pa-Ag, stainless steel, high- & low-gold alloys
97
Electrodeposition

98. Electrodeposition
 Improved bonding due to improved wetting and reduced porosity at the
porcelain metal interface
 Electrodeposited layer acts as a barrier between metal casting &
porcelain to inhibit diffusion of atoms from metal into porcelain
 Gold colour of the oxide film enhances the vitality and esthetics of the
porcelain
 Tin oxide aids in chemical bonding
 The deposited layer acts as buffer zone to absorb stresses caused by
differences in Coe. of thermal expansions
98
Advantages

99. Advantages of Metal-Ceramic
 High strength & durability
 High fracture resistance
 Permanent esthetic quality compared to acrylic veneer
 No staining along the interface between veneer & metal
 Adequate marginal fit
99
 Flexure strains produced in long span bridges may fracture ceramics
 Slightly poor esthetics
 Darker margins near the gingiva
Disadvantages

100. 1.Metal – Porcelain
Seen when metal surface is devoid of oxides or due to porous and
contaminated metal surface.
2.Metal oxide-Porcelain
Oxide layer remains firmly attached to metal, seen mostly in base
metal alloys.
3.Metal –metal oxide
Metal oxide remains attached to porcelain, seen in base metal
alloys due to overproduction of chromium and nickel oxides.
100
Bond Failures
O’ Brien (1977)

101. Bond Failures
4.Metal oxide –metal oxide
Fracture within the metal oxide.
Results from overproduction of oxide causing sandwich effect
between metal and porcelain.
5.Cohesive within metal
Common in bridges where joint area breaks, rare in single crowns.
6.Cohesive within porcelain
Tensile failure within porcelain. 101

102. Interfacial bond failure occurs primarily at three sites
 Along the interfacial region between
opaque porcelain and the interaction
zone.
 Within the interaction zone.
 Along the interfacial region between
the metal and the interaction zone.
102

103. Porcelain Teeth
 High-fusing or medium-fusing porcelains
 Manufactured by packing two or more porcelains of differing
translucencies for each tooth into split metal moulds & then fired at
high temperature
 Mechanical interlocking to denture base
 Anterior teeth : projecting metal pins
 Posterior teeth : diatoric holes
103

104.  More natural looking than acrylic teeth
 Excellent biocompatibility
 More resistant to wear than natural teeth
 Brittle
 Clicking sound on contact with opposing teeth
 Require greater inter-ridge distance (cannot be ground like acrylic
teeth without destroying diatoric channels)
 Higher density- increases the weight
 Opposing natural teeth wear
Disadvantages
Advantages
Porcelain Teeth…..

105. 105
All- Ceramic Restoration
 Excellent esthetics as all its thickness is for the porcelain.
 Earlier made up of traditional low-fusing porcelain fired onto a thin
platinum foil. – PJC
 To improve its strength – use of a strong core of ceramics
underneath the traditional porcelain.
Core ceramics include:
 Aluminious based ceramic
 Magnesia based ceramic
 Glass infiltrated aluminous ceramic

106. Aluminous porcelains (Hi-Ceram)
 Mclean and Hughes - 1965
 Contains 40-50% alumina
 Strengthens ceramic by interruption of crack propagation
 Used to construct core of PJC over which conventional enamel and
body porcelain are condensed
Mc lean 1979 Five year failure rate 2% for anteriors 15% for
posteriors
Seiber et al 1981: light reflection better than porcelain fused to metal

107. Aluminous porcelains….
 More esthetic than PFM
 Strength twice that of conventional porcelain
 Requires less removal of tooth structure
Disadvantages
Advantages
 Inadequate strength to be used on posterior tooth
 More sintering shrinkage

108.  Used in place of aluminous core porcelains
 High Coe. of thermal expansion (14.5 x10-6)
Magnesia core porcelains

109. A glass ceramic material that can be casted using the lost wax process
1968 Mc Culloch
Castable Ceramics
 Di-Cor
 Cerestore
 IPS Empress
 New types
Cera pearl
Optimal pressable ceramic
Olympus castable ceramics

110. Castable glass ceramic
 It is formed in to desired shape as a glass then subjected to heat
treatment to induce devitrification of glass
 Known as ceramming
 The crystalline particles thus formed interrupts crack propagation &
improves strength and toughness
 The crown is cast at 1380oc
 Final shading is achieved with external staining

111. Dicor
 Dicor by Corning glass works
 excellent esthetics because of the “chameleon” effect.
 contains about 55 vol% of tetrasilicic fluormica crystals
 Increased strength, thermal shock resistance, decreased translucency
 Dicor MGC is a higher quality product that is crystallized by the
manufacturer and provided as CAD – CAM blanks or ingots
 Low tensile strength
 Inability to be colored internally

112. Dicor ceramic crown

113. Wax pattern
Spruing
Investing
Burnout
Divesting
Cast glass coping
Ceramming
1750 for 12hr
450 for 12 hr
Centrifugal
casting 2600 f

114. Ceramming Ceramming oven Crystallised glass coping
Conventional porcelain application & Firing Finished crown
Cerramming done from room temparature- 1900 f for 1½ hrs and sustained
for 6hrs inorder to form tetra silicic flouro mica crystals

115. Castable glass ceramic
 In another type ,ceramming produced hydrxyapatite crystals rather
than mica as in dicor
 Coors porcelain company produced Cerestore
 Cerestore contains 70% alumina and is partially crystallized as alpha-
Al203

116.  All ceramic crowns without a core
 contains up to 45 vol% tetragonal leucite.
 The greater leucite content leads to a higher modulus of rupture,
compressive strength and high thermal contraction of coefficient.
 This large thermal contraction causes mismatch between leucite and
the glassy matrix results in the development of tangential compressive
stresses in the glass around the leucite crystals when cooled, these
stresses can act as crack deflectors and contribute to increase the
resistance to crack propagation.
Leucite reinforced ceramic (Optec HSP)

117. Advantages
 High flexural strength
 Excellent esthetics
Disadvantages
 Abrasion against natural teeth is higher than that of conventional
feldspathic porcelain.
 Poor marginal fit due to sintering shrinkage
 Requires special equipment for fabrication
Indications
 Inlays
 Veneers
 Low stress crowns and veneers
Leucite reinforced ceramic (Optec HSP)

118. IPS-EMPRESS (Pressable Ceramic)
Hot pressed ceramics
Leucite reinforced
K2O – Al2O3 – 4 SiO2
Lithium Disilicate
reinforced
SiO2 – LiO2 – P2O5 – ZrO2
2 types
IPS Empress IPS Empress 2

119. IPS Empress
 Developed by Wohlwend at the dental institute, Zurich University,
1991
 Type of leucite reinforced pressable ceramics contains about 35
vol% leucite, available in pre-ceramed cylinders
 Crowns are formed using the lost-wax process and hotpressing
leucite reinforced material into the mold using special furnace

120.  Wax preparation is made and placed on a specially designed
cylindrical crucible former and invested using a phosphate bonded
investment, the mold is heated in a burnout furnace to 8500C.
Wax pattern Investing Burn out 8500 C
IPS Empress

121.  The pre- ceramed cylinder is heated to 1100oc at which it is
plastisized, injected under pressure at high temperature in to the
mould for complete filling of investment cavity
 Injected under pressure at high temperature for 45 minutes into a
mold to produce ceramic substructure.
Ceramic ingot &
Al plunger
Pressing under vaccum
11500C
Sprue removal
26 min hold
IPS Empress

122.  The crown is formed in dentin shades over which enamel layer is
added
 The crown can be finished by two techniques staining, glazing or
by layering, involving veneering porcelain.
122
IPS Empress
Edward B Goldin 2005 compared leucite IPS Empress with PFM
Mean marginal discrepancy 94 + 41 PFM
81 +25 IPS
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.

123.  Indications
Anterior crowns
Inlays
Laminate veneers
Post and cores
IPS Empress
Contraindications
Clinical crown length of the tooth is
exceptionally short
tooth, reduction would compromise
resistance and retention of the
preparation.
Parafunctional habit
 Advantages:
High flexural strength (126-165
Mpa )
No shrinkage after pressing
Excellent fit and esthetics
Stability of shape
 Disadvantages:
Limited to single tooth restoration
Potential to fracture in posterior
areas

124. IPS Empress

125. PROPERTIES
 Flexural Strength - 120 Mpa initially and 182 Mpa
after heat treatment.
 Fracture toughness - 1.3 Mpa.
 Abrasion behaviour and Translucency -similar to that of
natural teeth
 Solubility - <200mg/cm2
 Pressing temperature - 11800 C
 Application of the - 9100 C
sintered glass ceramic
IPS Empress

126. IPS Empress 2
 To extend the use of resin-bonded ceramic restorations and use them for
bridge construction, a glass ceramic lithium based system has been
developed.
 The framework is fabricated with lost-wax and heat-pressure technique
 IPS Empress 2 has a core of lithia disilicate crystals in a glass matrix
and veneering ceramic contains apatite crystals which causes light
scattering similar to that of enamel
 The core microstructure of the two is different which is responsible for
slight decrease in translucency of IPS Empress 2
Lithium Disilicate reinforced

127. Full contouring Cut back
Sprued pattern
Investing Ingot pressing
IPS Empress 2

128.  The needle-like crystals cause cracks to deflect, thus the
propagation of cracks through this material is arrested by the
lithium disilicate crystals, providing a substantial increase in the
flexural strength.
IPS Empress 2

129.  INDICATIONS
 Three unit bridges for the anterior and posterior regions upto the
first premolar
 Crowns in anterior and posterior regions

 CONTRAINDICATION
 Short crown length
 Parafunctional habits
IPS Empress 2

130. In-ceram
A process used to form green ceramic shape by applying a slurry
of ceramic particles and water or a special liquid to a porous substrate
such as a die material, there by allowing capillary action to remove water
and densify the mass of deposited particles
Flexural
strength 350 MPa 500 MPa 700 MPa
In-ceram Alumina In-ceram
Spinell
In-ceram
Zirconia
( Slip casting technique )
Saadoun 1989

131. Glass infiltrated alumina core porcelain- Inceram
 Relies on “slip casting” to produce high strength core
 Fine sized alumina core with improved strength
 The core is fired for 10hrs at 1100oc in a special furnace
 Glass is infiltrated in to core frame work over 4 to 5 hrs at 1120oc
by capillary action, enhancing colour and strength

132. Glass infiltrated alumina core porcelain-
INCERAM(ICA)
 The core of ICA consists of 70 wt% alumina
 infiltrated with 30wt% sodium lanthanum glass.
 Advantages
 Four times more strength than other ceramics
 Enhanced marginal adaptation
 Disadvantages
 Poor esthetics
 Complex procedure
 Cost
 Indications
 Anterior crowns and bridges
 Posterior crowns

133. Cross section of an INCERAM crown

134. Al2O3 slip Glass infiltration
Vita Inceramat3
Giordono 1995 : Al2O3 Core glass infiltrated Ceramic > Strength
than Hi-Ceram, Di-Cor & Feldspathic Porcelain
Vaccumat 4000 Premium

135. Duplication
In-Ceram
refractory dies
In-Ceram
application
Al2O3 slip
10 hrs 1120 c-
2hrs
vita inceramat
Working model
Glass infiltration
4hrs 1100c
Shrinkage of dies

136. Application of body
and incisal porcelain
Postoperative veiw
of In-Ceram crowns
Finished In-
Ceram copings
(Air abraded)
Finished crowns
Preoperative veiw
Probster et al : Strength of In-Ceram > IPS Empress < PFM

137. Glass infiltrated spinell core (Inceram Spinell) (ICS)
 Offshoot of inceram
 It uses MgAl2O4
 More translucent and so more esthetic
 Strength is low
Inceram – Zirconia (ICZ)
 Has a core of 30 wt % zirconia and 70 wt % alumina
 Strongest and toughest of all three core ceramics
 Its use is limited to posterior crowns and FPDs because of its high
level of core opacity

138. CAD-CAM Ceramics
COMPUTER AIDED DESIGN-COMPUTER AIDED
MANUFACTURING
Examples - Cerec (Sirona), Sirona InLab, Everest (Kavo),
Cercon (Dentsply), Lava (3M ESPE), Zeno (Weiland), 5-
tec (Zirkonzahn), etc
The CAD-CAM system consists of 5 essentials
Scanner or digitizer – Virtual impression
Computer – Virtual design (CAD)
Milling station – Produces the restoration or
framework
Ceramic blanks – Raw material for the restoration
Furnace – For post-sintering, ceramming etc.

139. 139

140. 140

141. 141

142. 142

143. 143

144. 144

145. 145

146. 146

147. 147

148. Copy milled ceramics
 A new system (Celay by Mikron Technologies, Switzerland) uses a
copy milling technique to produce ceramic cores and substructures for
bridges
 A pattern of coping is prepared directly or indirectly with special blue
resin based composite
 A tracing tool passes over the pattern and guides a milling tool which
grinds a copy of the pattern from a block of ceramic (Inceram or
Inceram spinell)
 It is then infiltrated with glass and veneered with porcelain and fired to
complete the restoration

149.  Introduced in 1992, by Dr. Stefan Eeidenbaez, Zurich
 Uses copy-milling technique to manufacture ceramic inlays or
onlays from resin analogs
 It is fine grained feldspathic porcelain that is said to reduce the
wear of antagonist tooth structure
 Mechanical device based on pantographic tracing of a resin inlay
or onlay fabricated directly onto the prepared tooth or onto the
master die
 Material used is a ceramic blank available in different shades,
contains sanidine as the major crystalline phase within a glassy
matrix.
Celay

150. Celay
 Scanning of the prepared cavity is done with a 3-D scanner,
restoration is designed from the image shown on the computer
screen by using a series of icons or symbols
 Can electronically design the restoration by moving a cursor along
the limits of the preparation, thereby defining its boundaries
 Design phase usually takes from 2 to 8 minutes
 After data have supplied, the computer selects the size of ceramic
block to be used in the milling process
 Diamond wheel is driven by the electric motor, which generally
takes 4 to 7 minutes to complete the procedure

151. CELAY
 It is then infiltrated with glass and veneered with porcelain and fired to
complete the restoration
 Cementation involves etching the tooth with a 37 % solution of
phosphoric acid for 20 seconds, tooth is then washed and dried and a
bonding agent is applied, ceramic restoration is etched on its
undersurface, outside the mouth
 Dual cure microfill composite resin luting agent is used to bond the inlay,
onlay or veneer, after photocuring the occlusal anatomy can be created,
accomplished intraoraly with fine-particle diamonds.

152. CELAY
 ADVANTAGES
Single appointment
Bonded restoration for strength.
Reduced marginal gap
Hardness similar to enamel
Less fracture of the inlay because it is milled from a solid
Homogeneous block
Excellent polishing characteristics, esthetics
Preparation, fabrication, Cementation in 1 to11/2 hours.

153. Procera
 Introduced in 1994
 Embraces the concept of CAD/CAM to fabricate dental restorations
 Available as Procera laminate
 Procera crowns
 Procera Bridge
 Procera Implant Bridge
 This crown is composed of a densely sintered high-purity
aluminum oxide coping that as combined with the low-fusing
Allceram veneering porcelain
 Content of aluminum oxide in these coping is 99.9% and the
strength for this ceramic material is highest among all-ceramic
restoration

154. PROCERA PREPARATION
 Die is prepared from impression, scanned at a local laboratory,
which is saved as file in computer and
 send to laboratory in Sweden, where coping is
 prepared
 Coping is produced by a special process, which
 involves sintering 99.5% pure alumina at
 1600–1700°C,fully densified
 coping is then returned to the dental laboratory for building in the
crown’s aesthetics using compatible feldspathic glasses,
turnaround time is approximately 24 hours

155. PROCERA
 ADVANTAGES
 Biocompatibility -Aluminum oxide coping material does not show
any leakage or dissolution of aluminum at any of the pH levels
 Occulsal surface will not damage the opposing natural tooth
 Translucency-Procera coping is translucent, thus will not allow any
staining of the underlying dentin
 High strengthFlexural strength 700 mpa.
 DISADVANTAGES
 Very few laboratories offer this system
 INDICATIONS
 Used in metal sensitive patients

156. Procera Alltitan
 In this technique titanium core is used, the external contours of the
individual titanium cores for bridges are milled and graphite rods
create the fitting surface by the spark erosion process.
 Individual components of the bridge are then welded by laser before
the addition of special porcelains to layer the surface to the full contour

157. CEREC
 Introduced in 1991, feldspathic porcelain of high strength and fine
grain size is used.
 Used in cases of inlays, onlays, partial crowns, crowns (posterior
& anterior), and veneers
 One of the most researched restorative systems on the market,
with documented success rates of more than 90% after 10 years

158. Preparation Of CEREC
 A cast of the prepared teeth made using a specialized CAD-CAM-
compatible stone that is sprayed with Quickcheck indicator spray
 After the die preparation, the die is loaded into the bridge holder of
the CEREC inLab unit; the bridge holder is then placed in the
machine for scanning.
 A digital image of the cast is displayed on
 the screen, In-Ceram block is inserted
 into the unit for automatic milling

159. CEREC
 After milling is complete, the fit of framework
 is tested on the die stone.
 Consistency of a coping is chalk-like, any
 necessary adjustments can be accomplished
 quickly and easily
 The proper amount and shade of glass required
 is applied
 The coping is placed in the In-Ceram furnace
 for infiltration.

160. CEREC
 Excess glass is removed by sandblasting the coping, luminary coat
is applied for refraction of light.
 The appropriate shade of porcelain and modifiers are applied for a
natural appearance
 Glaze is applied, and the restoration is now complete and ready for
placement

161. LAVA
 Introduced in 2002, Lava uses a laser optical system to digitize
information from multiple abutment margins
 The Lava All-Ceramic System comprises a CAD/CAM procedure
for the fabrication of allceramic Crowns and Bridges for anterior
and posterior applications.
 CAD software scan the die automatically finds the margin and
suggests a pontic, the framework designed to be 20% larger to
compensate for sintering shrinkage

162. LAVA
 After the cut dies of the preparation is made, the milling center
will digitalize the model by using the optical scanner Lava Scan
 The restoration will then be virtually designed on the monitor
using a CAD, the data is sent to Lava Form, a milling unit (CAM)
 The restoration is milled from a pre-sintered zirconia blank,
which can be colored in 8 different shades and which is then
sintered to its final density in the furnace
 The milling center returns the finished framework to the lab who
will then veneer the framework with Lava Ceram and give it the
final artistic finish.

163. LAVA
 ADVANTAGES
 With the classic color scheme, all tooth shades can be easily
reproduced, special effect components and stains lead to a natural
esthetic
 High level of biocompatibility
 Anterior and posterior crown and bridge

164. Conclusion
The difference with & without Ceramics is self evident
164

165.  Journal of Indian Prosthodontic society –oct.2002,vol.2
no.3
 Notes on dental materials- V K Subbarao
 Basic dental materials- Manappallil
 The science and art of dental ceramics –Mc lean vol 2
References
165

166. References
 Anusavice : Philips’ Science of Dental Materials Xth &
XIth Edn.
 Craig : Dental Materials : Properties & Manipulation VIth,
VIIth & VIIIth Edn.
 J. F. McCabe : Applied Dental Material VIIth Edn.
 Jack Ferracane : Materials in Dentistry Principles &
Application
166

167. Repair of Ceramic Restoration
 This can be done if the fracture is not too
extensive.
 Repaired in the mouth using a resin
composite in dry field.

168. Residual stresses in porcelain when coe. Of
thermal expansion of porcelain is more than
metal

169. Metal-Ceramic Bonding
 Fusion temperature of ceramics : 900oC-1000oC.
 Highly viscous liquid having large surface tension (365
dynes/cm).
 Angle of contact (130o) with alloy surface.
 Ceramic liquid does not wet & bond with metal surface.
169