2. ALL CERAMIC MATERIALS Presented By : Dr Rasleen Kaur
Sabharwal Dept Of Prosthodontics Sri Rajiv Gandhi Dental College
And Hospital 3. CONTENTS Introduction History of ceramics
Composition of ceramics Properties of ceramics Classification of
dental ceramics Methods of strengthening ceramics Conventional
powder slurry ceramics 4. .Castable ceramics Machinable ceramics
Pressable ceramics Infiltrated ceramics Zirconia based systems
Conclusion References 5. INTRODUCTION Dental ceramic is one of the
most biological and esthetically acceptable material in dentistry.
Ceramics are used for manufacturing artificial teeth, pontics,
facing, crowns and fixed bridges. Dental porcelain in this domain
is superior over polymers and reinforced polymers regarding
toothshade reproduction, translucency, biological compatibility,
chemical stability and abrasion resistance. 6. Ceramic is derived
from GREEK word KERAMI KOS meaning Burnt earth Ceramics: compounds
of one or more metals with a nonmetallic element(usually silicon,
boron, oxygen) 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 . (G.P.T 8, Anusavice) 7. Porcelain : a
ceramic material formed of infusibleelements 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 8) 8. HISTORY &
EVOLUTION OF CERAMICS 9. The first porcelain tooth material was
patented in 1789 by a French dentist deChemant in collaboration
with a French pharmacist Duchateau. The first commercial porcelain
was developed by Vita Zahnfabrik in about 1963JPD 1996 JAN 18-32;
CERAMICS IN DENTISTRY : HISTORICAL ROOTS AND CURRENT PERSPECTIVE
10. 1887 PJC CH. Land (platinum foil technique)1940 with advent of
acrylics PJC lost popularity1957 Vines and Sommelman Vaccum
firing1962 PFM Weinstein1965 McLean and Hughes aluminium core
porcelain 11. 1968 castable ceramics (Mc Culloch) 1970 hydrothermal
ceramics 1980 Duceram LFC 1980 Cerec system (Brain.A.g,
Switzerland) 1984 Magnesia reinforced porcelain 12. 1988 Inceram
1994 - Cerec 2 system (Morman & Brandestini) 2006 Cerec 3
(Akbar, Walker, Williams) 13. Composition of a dental porcelain
(feldspathic)Material Silica Alumina Boric oxide Potash Soda Other
oxidesweight% 63 17 7 7 4 2 F e ld s p a r D e n ta l P o r c e la
inD o m e s tic P o r c e la in S to n e w a reK a o linE a rth e n
w a reQ u a rtz 14. The various ingredients used in different
formulations of ceramics are : 1.Silica (Quartz or Flint) Filler
2.Kaolin (China clay) Binder 3.Feldspar Basic glass former 4.Water
Important glass modifier 5.Fluxes Glass modifiers 6.Colour pigments
15. 7.Opacifying agents 8.Stains and colour modifiers 9.Fluorescent
agents 10.Glazes and Add-on porcelain 11.Alumina 12.Alternative
porcelainadditivesto 16. Silica Pure Quartz crystals (SiO2) are
used for manufacturing dental porcelain. Quartz (crystalline
silica) is used in porcelain as a filler and strengthening agent.
17. Kaolin ( White China Clay) Its functions are: It increases the
moldability 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. 18. Feldspars Types of feldspar : Soda
feldspar Decreases fusion temperature Potash feldspar Increases the
viscosity of glass. 19. 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. The glassy phase forms a translucent glassy
matrix. Leucite formation: Another important property of feldspar
is its tendency to form the crystalline mineral leucite. 20.
Leucite Is a potassium-aluminum-silicate mineral with a high
coefficient of thermal expansion ( 20-25x10o/ oC) compared to
feldspathic glasses ( 10x10o/oC). It is an artificial crystal
feldspathoid ( K2O.Al2O3.4siO2) formed by the incongruent melting
(Incongruent melting is the process by which one material melts to
form a liquid plus a different crystalline material) of feldspar (
K2O.Al2O3. Al2O3-4SiO2).Annu Rev Mater Sci 1997 27:443-68 ceramics
in restorative and prosthetic dentistry : J Robert Kelly 21.
Functions 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. 22.
Glass formers Glass is basically composed of silica (SiO2) with
oxides of Sodium, Potassium, Calcium, Barium etc. The principal
anion in all glasses is O2 ion, which forms very stable bonds with
small multivalent cations such as Silicon, Boron, Germanium or
Phosphorus resulting in formation of random networks of SiO4
tetrahedral in glass. These ions are thus termed as Glass Formers.
23. Glass Modifiers Can be defined as elements that interfere with
the integrity of the SiO2 (glass) network and alter their
three-dimensional state. Their functions are: to decrease the
softening point by reducing the amount of cross linking between
oxygen and glass forming elements. decrease the viscosity (flux
action increasing the flow) 24. Intermediate Oxides Addition of
glass modifiers to reduce the softening point also decreases the
viscosity, resulting in slump or pyroplastic flow; hence it is
necessary to produce glasses with high viscosity as well as low
firing temperature. This can be done by the incorporation of an
intermediate oxide such as alumina (Al2O3), to increase the
viscosity of glass. 25. Boric Oxide fluxes 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. 26. Water Although not an intentional addition, water is
an important glass modifier. 27. Colouring agents Dental porcelains
colored by the addition of concentrated colour frits which are
prepared by fritting high-temperature resistant colouring pigments
(generally metallic oxides) into the basic glass. 28. The color
pigments used are: Pink - Chromium or chrome-aluminia Yellow-indium
(lemon) Titanium Blue -Cobalt salts in the form of oxide Green -
Chromium oxide Grey -Iron oxide (black) or platinumoxide 29. Other
pigments used may be Titanium oxide yellow brown, manganese oxide-
lavender, iron/nickel oxide-brown, and copper oxide green. 30.
Opacifying agents The translucency of porcelain is not suitable to
produce dentin colours in particular, which requires greater
opacity than that of enamel colors. An opacifying agent maybe
incorporated, which generally consists of a metal oxide. The common
metallic oxides used are Cerium oxide Titanium oxide 31. Tin oxide
and Zirconium oxide (ZrO2)- most popularly used opacifying agent
(usually added with the concentrated color frit to the porcelain
during final preparation). 32. Stains & Colour Modifiers The
stains and colour modifiers supplied with dental porcelain are
prepared in much the same way as colour frits. 33. Properties of
porcelain: Strength: Porcelain has got good strength, but is
brittle and tends to fracture. Strength is usually measured in
terms of flexural strength Flexural stength: Ground porcelain -
75.8 Mpa. Glazed porcelain - 141.1Mpa. Compressive strength 331
Mpa. Tensile strength 34 Mpa .Low because of surface defects like
porosities & microscopic cracks Shear strength - 110Mpa. 34.
Specific Gravity: True Specific Gravity is 2.242. Fired porcelains
sp gravity is less due to presence of air voids Dimensional
stability: Dimensionally stable Chemical stability: Insoluble and
impermeable to oral fluids. Resistant to most solvents. HF acid is
used to etch porcelain to improve bonding of the resin cement 35.
Esthetic properties: Able to match adjacent tooth structures in
translucency, colour & intensity. Colour stability excellent
,retain its colour & gloss for years. Biocompatibility:
Excellent compatibility with oral tissues. 36. CLASSIFICATION OF
CERAMIC MATERIALS 37. Dental porcelains are classified according to
the firing temperatures as: High fusing 1300C (2372F) Medium fusing
1101 1300C (2013 2072 F) Low fusing 850 1100C (1962 2012F)
Ultra-low fusing Strength than Hi-Ceram, Di-Cor & Feldspathic
Porcelain 169. Working modelIn-Ceram applicationShrinkage of
diesDuplicationAl2O3 slipIn-Ceram refractory diesvita inceramat120
0C- 2hrsGlass infiltration 4hrs 11000C 170. Finished InCeram
copings (Air abraded)Application of body and incisal
porcelainPreoperative veiwFinished crownsPostoperative veiw of
In-Ceram crownsProbster et al : Strength of In-Ceram > IPS
Empress < PFM 171. ZIRCONIA BASED SYSTEMS YTTRIUM TETRAGONAL
ZIRCONIAPOLYCRYSTALS (Y-TPZ) BASED The most recent core materials
for all-ceramic FPDs, (Y-TPZ) based materials were first used in
orthopedics for total hip replacement, and were successful because
of the materials excellent mechanical properties and
biocompatibility.It was introduced into dentistry in the early
1990s for using as implant abutments. 172. As Y-TPZ core are glass
free and because they have a polycrystalline microstructure they do
not exhibit the phenomenon of sub critical crack propagation and
stress corrosion caused by water in the saliva reacting with the
glass. 173. Y-TPZ based materials demonstrated a flexural strength
of 900 to 1200 MPa and fracture toughness of 9 to 10 MPa.m . It
also demonstrated a fracture resistance of more than 2000 N under
static load.JPD DEC 2004 ; 92:557-62 Contemporary materials and
technologies for all ceramic fixed partial dentures: a review of
literature 174. Y-TPZ core is relatively translucent and, at the
same time may mask the underlying discolored abutment. Moreover it
can be colored in 1 to 7 shades corresponding to the Vita- Lumin
shade guide. This ability to control the shade of the core may
eliminate the need for veneering. 175. Y-TPZ based core is
radio-opaque which facilitates radiographic evaluation of the
restoration. Adhesive cementation is not mandatory and traditional
luting agents may be used. They also require relatively small
connector area as compared to most other all-ceramic systems. 176.
CERCON AND LAVA ZIRCONIA CORE CERAMICS 177. THE CERCON ZIRCONIA
SYSTEM Manufacturer-Dentsply Ceramco NJ For posterior crowns and
three unit FPDs Fracture resistance of three unit FPD is 1278 N.
(for ICA it is 514N and for Empress2 it is 621 N) 178. After
preparing the teeth an impression is made and sent to the
laboratory, where it is poured with a model material. A wax pattern
approximately 0.8mm in thickness is made for each coping or crown
areas of the framework of an FPD 179. The wax pattern is anchored
on the holding appliance on the left side of the scanning and
milling unit. A presintered zirconia blank is attached to the right
side of the unit. After the unit is activated the blank is
rough-milled and fine-milled on occlusal and gingival aspects in an
enlarged size to compensate for the 20% shrinkage that will occur
during subsequent sintering at 13500C. The processing time for
milling is approximately 35 min for crowns and 80 min for a
four-unit FPD. 180. The zirconia copping is then placed in the
Cercon furnace and fired at 13500C for 6 hrs to fully sinter the
yttria stabilized zirconia core copping or framework. The sintering
shrinkage is achieved uniformly and linearly in the 3 dimensional
space. After any subsequent trimming with a water cooled highspeed
diamond bur the finished ceramic core is then veneered with a
veneering ceramic and stain ceramic. 181. Zirconia blockMilled
BlockFPD framework tried on Working Cast 182. .......... LAVA and
Cercon systems use partially sintered blocks of Y- TZP for milling
the framework, but DCM ( direct ceramic machining process ) uses
fully sintered blanks or HIP (hot isostatically pressed
blanks)Prague medical report vol 108 ( 2007) no 1 pg 5-12 :
Zirconia- a new dental ceramic material 183. CONCLUSION No
currently available restorative system can be considered the ideal
replacement for natural tooth structure. However, in recent years
there has been a great amount of attention given to research on and
development of ceramic systems for restorative use. Ceramics are
playing an increasingly important role in restorative dentistry,
and further improvements in fracture resistance and wear properties
will no doubt enhance their restorative use. The demand for
esthetic dentistry is expected to continue and will be influencial
in determining the range of the products available. 184. REFERENCES
David A Graber, Ronald E Goldstein- porcelain and composite inlays
and onlays esthetic posterior resorations. Aschheim Dale- esthetic
dentistry 2nd edition Robert G Craig- restorative dental materials
Phillips- science of dental materials 10th edition John McLean- the
science and art of dental ceramics Pubmed Sciencedirect.com 185.
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