Metal free ceramics /certified fixed orthodontic courses by Indian dental academy

METAL FREE CERAMICS
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


INTRODUCTION
• Of all materials used in dentistry to restore
the natural dentition, ceramics have by far
the best optical properties to mimic tooth
structure in appearance translucency, light
transmission and biocompactibility give
dental ceramics highly desirable esthetic
properties.


All ceramic inlays,onlays,veneers and
crowns are some of the most esthetically
pleasing prosthodontic restoration. Because
there is no metal to block light transmission,
they resemble natural tooth structure better
in terms of color and translucency than any
other restorative option.


DEFINITION
• ACCORDING TO GPT 1999:
•

CERAMIC IS DEFINED

AS:
•
Compound of one or more metal with a
nonmetallic element, usually oxygen.They
are formed of chemical and biochemical
stable substances that are strong, hard,brittle
and inert non conductors of thermal and

PORCELAIN
• Is defined as a ceramic material formed of
infusible elements joined by lower fusing
material.
• Most dental porcelain are glasses and used
in fabrication of teeth for dentures, pontics,
metal ceramic restoration ,crowns and other
restoration.

COURTESY:ANUSAVICE
• CERAMIC is a compound of metallic and
nonmetallic elements.
• Metals:Aluminium, Calcium, Lithium,
Magnesium, Potassium, Sodium, Tin,
Titanium,Zirconium.
• Nonmetals:Silicon, Boron, Fluoride,
Oxygen.

• They may be used as a single structural
component .e.g:CAD CAM inlay
• Or as one of the several layers.e.g:
Fabrication of ceramic based prosthesis.
• ALL PORCELAIN AND GLASSCERAMICS ARE CERAMIC ,BUT NOT
ALL CERAMICS ARE PORCELAINS OR
GLASS CERAMICS.
•

CONTINUED….
• They are formulated to provide one or more
of the following properties:
• 1.CASTABILITY
6.COLOR
• 2.MOLDABILITY 7.MACHINABILITY
• 3.INJECTABILITY 8.ABRASION
RESISTANCE
• 4.TRANSLUCENCY 9.STRENGTH
• 5.OPACITY

10.TOUGHNESS


HISTORY OF DENTAL
CERAMICS
• Dental technology existed in ETRURIA as early
as 700 BC and during Roman 1st century BC but
remained undeveloped until 18th century.
• Material used for artificial teeth in 18th century is
•
1.Human Teeth.
•
2.Animal teeth carved to the size &shape
•
of human teeth.
3.Ivory.
•
4.Mineral or porcelain teeth.

Continued…
• DISADVANTAGE:
•
1.Human teeth-costly& scarce
•
2.Animal teeth-unstable
towards the corrosive agents in saliva
•
3.ivory&bone- contains pores &
are easily stained.


Continued…
 Mineral teeth or porcelain dentures greatly
accelerated as an end to the usage of human and
animal teeth.
 Feldspathic dental porcelain were adapted from
European triaxial white ware formulations( clayquartz- feldspar).


Continued…
• After decades of effort, Europeans mastered the
manufacture of transluenct porcelain, comparable
to the porcelain of chinese by 1720.
 The use of feldspar to replace lime & high firing
temperature are the both critical developments.


Continued…
• 1723,Enameling of denture metal bases was
described by PIERRE FAUCHARD in LE
CHIRURGIEN DENTISLE. He was
credited with recognizing the potential of
porcelain enamels and initiating research
with porcelain to imitate color of teeth &
gingival tissues.


Continued…
• 1774, a parsian apothecary ALEXIS
DUCHATEAU with assistance of parisian
dentist NICHOLAS DUBOIS DE
CHEMANT continually improved porcelain
formulations.
 In England DUDOIS DE CHEMANT
procured supplies from collobration with
JOSIAH WEDGWOOD.

Continued…
• 1808, GIUSEPPANGELO FONZI of paris
introduced individually formed porcelain
teeth that contained embedded platium pins
known as TERRO-METALLIC INCORRUPTIBLES and their esthetic
&mechanical versatility provided major
advance in prosthetic dentistry.


Continued…
• Improvement in transluency&color of
dental porcelains were realised through
developments that ranged from
formulations of ELIAS WILDMAN in 1838
to vaccum firing in 1949


Continued…
• Glass inlays(not porcelain)were introduced
by HERBST in 1882 with crushed glass frit
fired molds made of plaster&asbestos.


Continued…
• In 1885 LOGAN resolved the retention
problem encountered between porcelain
crowns&post that were commonly made of
wood by fusing the porcelain to platinum
post-RICHMOND CROWN.
• These crowns represent the first innovative
use of metal ceramic system

Continued…
• In 1886, combining burnished platinum foil
as a sub structure with the high controlled
heat of a gas furnance,LAND introduced
first fused feldspathic porcelain
inlays&crowns.
• All porcelain crown system despite of its
esthetic advantages failed to gain
widespread development until alumina was
used as reinforcing paste.

Continued…
• A noteworthy development occurred in
1950 with addition of leucite to porcelain
formulation that elevated the coefficient of
thermal expansion to allow fusion to certain
gold alloys to form complete crowns and
FPD.
• Refinements in metal ceramic systems
dominated dental ceramic research during
the 35years that resulted in improved

Continued…
• In 1965 McLEAN&HUGHES developed a
PJC with a inner core of aluminous
porcelain containing 40% to 50% alumina
crystals to block the propagation of cracks.
• The inner core is layered with conventional
porcelain resulting in a restoration approx
twice as strong as traditional PJC.But the
structure is still insufficient for anything but
anterior crowns.

Continued…
• Fracture resistance of the aluminous PJC
was improved by a technique in which the
platinum matrix is left in completed
restoration.
• The platinum foil decreased the amount of
light transmitted which diminishes
somewhat esthetic advantage of all ceramic.

Continued…
• The introduction of a “shrink-free”all
ceramic crown system(cerestore,coors
biomedical)& castable glass ceramic crown
system(dicor,dentsply) in 1980s provided
additional flexibility for achieving esthetic
results.
• Advanced ceramic systems introduced with
innovative processing methods stimulated
renewed interest in all ceramic prosthesis.

DEFINITION
• ACCORDING TO GPT 1999,
• ALL CERAMIC is defined as ceramic
restoration that restores a clinical crown
without a supporting metal substructure.


COURTESY:ANUSAVICE
• PJC:
•
One of the first types of all ceramic
crown made from a low strength aluminous
core porcelain & veneering porcelain(with
matching thermal contraction coefficient)
without the use of a supporting metal
substrate except in some instances for a thin
platinum foil.

• CJC:
•
An all ceramic crown without a
supporting metal substrate that is made
from a ceramic with a substantial crystal
content(>50 vol%)from which its higher
strength and/or toughness is derived.These
crowns are distinguished from PJC that are
made with low strength core
material,usually aluminous porcelain or

DISADVANTAGES OF
METAL CERAMICS
• Metal margin exposure
• To achieve better esthetics,the facial margin
of an anterior restoration is often placed
subgingivally which increases the potential
for periodontal diseases.
• Risk of over contouring-metal 0.5mm and
the rest is ceramic material.

• Because of glass like nature of veneering
material they are subjected to brittle
fracture.
• Metal bases affect the esthetics of porcelain
by decreasing the light transmission through
the restoration and by creating metal ion
discoloration.

• Fit of long span bridges may be affected by
the creep of the metal during successive
bakes of porcelain.
• Porcelain made in metal ceramic technique
are more liable to devitrify which can
produce cloudiness.
• Some patients have allergic reaction or
other sensitives to metal.

• These drawbacks have prompted the
development of new all ceramic system that
do not require metal,yet have high strength
and precission fit of cerametal system.


STRENGTH
• Strength is greatly influenced by presence
of surface flaws acting as stress
initiators&causing widening&propagation
of micro cracks through material from the
surface.Therefore dental porcelain is much
weaker in tension than in compressive and
is prone to brittle fracture.


• Strength is influenced by static fatigue
which is generally caused by a stress
dependent chemical reaction between water
vapour &surface flaw in the restoration.This
causes flaw to grow to critical
dimension,allowing spontaneous crack
propagation, resulting in a fracture with
comparatively little occlusal loading
particularly over long periods.

CLASSIFICATION OF
DENTAL CERAMICS
•
•
•
•
•
•

COURTESY:ANUSAVICE
Dental ceramics are classified according to
1.Types
2.Uses
3.Processing methods
4.By substructure material

•


TYPES
1.Feldspathic porcelain
2.Leucite reinforced porcelain
3.Aluminous porcelain
4.Alumina
5.Glass infiltrated alumina
6.Glass infiltrated spinel
7.Glass ceramic

USES
•
•
•
•
•
•

Denture teeth
Metal ceramics
Veneers
Inlays
Crowns
Anterior bridges

PROCESSING METHODS
• 1.Sintering
• 2.Casting
• 3.Machining


SUBSTRUCTURE MATERIAL
•
•
•
•
•

1.Cast metal
2.Swaged metal
3.Glass ceramic
4.CAD CAM porcelain
5.Sintered ceramic core


COURTESY:SHILLINGBURG
• According to firing temperature:
•
High fusing:-1,290-1,370 C(2,3502,500F)
•
Medium fusing:-1,090-1,260 C(2,0002,300F)
•
Low fusing :-870-1,065C(1,6001,980F)s

HIGH FUSING PORCELAIN
• Is used for manufacture of porcelain
teeth,also for some extent for PJC.
• Composition:
•
FELDSPAR-70% to 90%-matrix
•
QUARTZ-11% to 18 %-refractory
skeleton.
•
KAOLIN-1% to 10%-acts as a binder
when porcelain is ‘green’ or unfired.

LOW AND MEDIUM FUSING
PORCELAIN
• Manufactured by a process called fritting.
• Raw constituents of porcelain are
fused,quenched&ground back to an
extremely fine powder.


INTEREST FOR ALL
CERAMIC CROWNS
• It has more potential for more esthetic
anterior restoration.
• In PFM,alloys structure produces opaque
appearance and metal margin are often
visible.
• Selection of alloys for PFM is confusing
issue.
•

• High gold content alloys are relatively
expensive.
• Risk of metal allergy, bond
failure,porcelain discoloration


GENERAL CLASSIFICATION
•
•
•
•
•

Powder slurry/sintered porcelain.
Castable ceramics.
Pressable ceramics.
Infiltrated glass ceramic.
Machinable ceramic.


POWDER SLURRY
PORCELAINS


• Products are supplied as powder to which
ceramist adds distilled water to produce a
slurry,which is build up in layers on a die
material to form the contours of
restoration.The powder is available in
different shades and translucencies and are
supplied with characterstics stains and
glazes.

EXAMPLES
• OPTEC H.S.P(JENERIC/PENTRON)
• DUCERAM L.F.C(DUCERA INC)
• VITA HI-CERAM(VITA ZAHNFABRIK)


OPTEC H.S.P(HIGH
STRENGTH PORCELAIN)
• Leucite reinforced feldspathic porcelain
• The manufacturer disperses the leucite
crystals in a glassy matrix by controlling
their nucleation and crystal growth during
the initial production of porcelain powder.
• The leucite crystals added to the glass base
are 10microns in size and its concentration
is 50 to 60 wt%.

Body and incisal porcelain are pigmented to
provide desired shade&translucency.

• Greater strength so no core required.
• Leucite and glass matrix fused at 1020
deg C.


ADVANTAGES
•
•
•
•
•

1. Lack of metal or opaque substructure.
2.Good transluency.
3.Moderate flexural strength.
4.No special laboratory equipment needed.


• 5.Two and a half times stronger than
conventional porcelains.
• 6.It transmits,reflects&refracts light in the
same manner as natural teeth ideal for
laminate veneers.


DISADVANTAGES
• Porcelain margin inaccuracies caused by
porcelain sintering shrinkage.
• Potential to fracture in posterior teeth.
• Increased leucite content leads to in vitro
wear of opposing teeth.


DUCERAM L.F.C
• Composition: amorphous glass containing
hydroxyl ions.
• Manufacturer claims that this noncrystalline
structure has greater density,higher flexural
strength,greater fracture resistance and
lower hardness than feldspathic porcelain.


• High flexural strength results from an ion
exchange mechanism of hydroxyl ions
which is said to also promote a healing of
surface micro cracks.
• Decreased hardness is due to absence of
leucite crystals.


PROPERTIES
• Flexural strength-110 Mpa
• Hardness close to natural teeth due to
absence of leucite.
• Opalescence of natural teeth can be
reproduced.
• Fluorescence is very close to natural teeth.


ADVANTAGES
•
•
•
•
•

Excellent marginal adaptation.
No special equipment required.
Allow modification by repeated firing.
Abrasion rate close to that of natural teeth.
Good esthetic results.


INDICATION
• Ceramic inlays.
• Veneers.
• Full contour crowns.


CONTRA INDICATION
• Masking grossly discolored teeth.
• When aiming for high fracture resistance.


VITA HICERAM
• MATERIAL:
•
Higher content of aluminium
oxide/aluminium oxide reinforced.
• It consists of 50% of aluminium crystals in
a matrix of low fusing glass of matching
thermal expansion.
• Aluminous core porcelain are twice
stronger than regular porcelain.

MERITS
• Highly accurate margins.
• Higher melting points and greater stability.
• For both anterior and posterior crown
veneers.


CASTABLE CERAMICS
• These products are supplied as solid
ceramic ingots which are used for
fabrication of restorations using lost wax
and centrifugal casting technique.The
restoration is either covered by
conventional feldspathic porcelain or is
stained to obtain proper shading and
characterisation of final restoration.

• EXAMPLE:
•
Dicor(corning glass,Dentsply)micaceous glass ceramic.
• Dicor plus-Dicor coping with compatible
veneering porcelain.
• Cerapearl(Bioceram,Kyocera)Hydroxyapatite is a main crystalline phase.

DICOR
• Dicor castable glass ceramic is one of the
pyoceram ceramics manufactured by
STOOKEY of the corning glassware in
1978.
• Dicor is the first commercially available
castable ceramic material for dental use.
• Present system was introduced by PETER
ADAIR and DAVID GROSSMAN in 1984.

• It is a composite materials of a glassy
matrix phase and a crystal phase


COMPOSITION
•
•
•
•
•

SiO2-45%-70%w/w
K2O-20%w/w
MgO-3%-13%w/w
MgF2-4%-9%
Fluoride acts as a nucleating agent which
aids the growth of crystalline phase leading
to growth of 0.5-2 microns small tetrasilicic
crystals and it improves fluidity of molten
glass.

• Al2O3 and ZrO2-minor amountsincorporated for durability and fluorescing
agent for esthetics.


MATERIAL
• Dicor restoration is made by investing a
wax pattern and casting by last wax
process.
• Cast crown is a clear glass that must be heat
treated to form a crystalline phase
composed of tetrasilicic
fluoromica(K2Mg5SiO8O20F4) which
provides fracture resistance and
strength(Hoekstra 1986).

• Crystallisation procedure takes place during
heating the reinvested crown for 6hrs at
1070 C – causes the growth of microscopic
plate like crystals of crysyalline
material(mica)in the glass matrix.
• This crystal nucleation and crystal growth is
known as ceramming.
• It forms 45 vol %-glass matrix, 55 vol %tetrasilica fluoro mica crystals.s

• This causes mica to form a “STRONG
HOUSE OF CARDS”structure which
makes fracture propagation especially
equally difficult in all direction.
• It is highly transluescent.


CREATION OF CAST GLASS
CERAMIC RESTORATION
• Full anatomic wax up.


• Casting to a glassy
state.


• Ceramming to a
crystalline glass
ceramic.


• Applying external
colorants.


SURFACE REACTION
• Between investment material&glass leads to an
exchange of ions between the two as a result of
high temperature&long reaction time.
• Glass releases potassium ions(k ions)&takes up a
calcium ions . It loses fl ions from its surface.
• This leads to a composition at the glass surface
that is different from internal composition of the
glasses.

• The outer skin layer on dicor ceramic
contains needle like crystals of the silicate
enstatite(MgSiO3) oriented perpendicular to
the surface –ceram layer and is the site of
considerable residual porosity.
• This weakend surface layer reduces the
significantly the overall strength of the
material.

• Characterisation of crown is achieved by
surface glaze.


PROPERTIES
• 1.Strength:-Crystalline structure of this
material lessens the likelihood of crack
propagation because the lattice structure is
able to absorb compressive forces.
• 2.Abrasiveness:-The hardness coefficient&
wear characteristic is as same as enamel.
•
Cast ceramic-362KHN
•
Enamel-343 KHN

• 3.Light absorptive refraction:•
Glass ceramics refracts 75% of
entity light because of its organised
crystalline structure which a refractive
index similar to that of enamel which
guides the light deep into the ceram.
• It absorbs light from other teeth& filling
material creating a “Chameleon effect”.

• Cast glass ceramic are radiolucent & allow
radiographic examination of marginal
integrity,extreme thickness of bases & podt
& cores.


• 4.Compactibility:•
It exhibition less surface plaque
accumulation than enamel , cementum &
any other restoration material.
• fluoride content inhibition bacterial
colonisation.


• 5.Marginal adaptation:•
More consisten in terms of fit than
gold crowns(Malament&Grossman 1992).
• Thermal expansion of cast glass ceramic is
close to that of natural enamel.This causes
similar expansion & contraction during
normal temperature fluctuation,thus
maintaining a good marginal seal.

• 6.Thermal conductivity:•
Low thermal conductivity.


ADVANTAGES
• 1.Last wax-Casting fabrication
procedure/technique allow to easy morphology
control.
• 2.Fit of restoration is excellent.
• 3.wearing of opposing occlusion is predicted to
less than that of conventional porcelain.
• 3.Fluctural strength is greater than conventional.


• 4.Marginal porcelain opening is less when
compared to McCrown.
•
Dicor-30-60mm
•
Metal Ceramic Crown-62-65mm
• 5.Glazed proximal surface are very smooth
&resistent to plaque accumulation
• 6.Good esthetics & transluency.

DISADVANTAGES
• 1.Special equipment & cost.
• 2.The process is technique sensitive.
• 3.When colorant in surface stain, any grinding on
the restoration leads to anesthetic opaque white
areas.
• 4.High failures rate in posterior region of mouth.
• 5.Greater bulk in some cases decreases the
chameleon effect &esthetic results.

INDICATION
• 1.Anterior porcelain J C.
• 2.Inlays , onlays ,3/4 crown.
• 3.Partial veneers


CONTRA INDICATION
• 1.Clinical crown length in short-it would
compromise resistance & retention of the
preparation.
• 2.FPD.


DICOR PLUS CERAMIC
• Because of esthetic limitation-venering cutback
Dicor coping feldaspathic porcelain was
developed with intrifuging name”Willi’s Glass”.
• It provided perspective to recent introduction of
Dicor plus ceramic(Dentsply international).
• It is a compactible veneering porcelain for
fabricating “Willi’s Glass crowns”.


CERAPEARL(KYOCERA)
• It is CaOP2O5MgOSiO2 glass ceramic or
calcium phosphate glass similar to
hydroxyapatite of the enamel.


Composition
• CaOP2O5-aid in glass formalisation.It is the
main ingredient to form hydroxyapatite
crystals.
•
MgOCaO-covers viscosity
•
SiO2 with P2O5-forms matrix


Properties
• 1.It melts at 1460 C & casted which has an
amorphous microstructure and is reheated at
870 C for 1 hr-crystalline oxyapatite.
• 2.It is unstable & when exposed to moisture
forms crystalline hydroxyapatite.
• 3.It is similar to enamel providing superior
mechanical strength.

INFILTRATED GLASS
CERAMIC
• These are glass infiltrated core
ceramics.This involves slipcasting
technique for making core and the contours
of the restoration are obtained by individual
layering & staining technique.


• Example: Inceram (vita zahnfabrik)
•
Alumina
•
Ziremia
•
Spinell


INCERAM ALUMINA
• Inceram was evolved by research by
Dr.Mickael Sadoun in 1985 using alumina
as core material & was manufactured &
marketed by Vita Zahnfabrik,Germany.
• Inceram belongs to a class of materials
known as interpenetrating phase
composites.
•

• They contain atleast 2 phases that are
interwined or extend continously from
internal to external surface.
• They posess improved mechanical &
physical properties compared with
individual components.
•

• Have improved sterngth & fracture
resistance because a crack must pass
through alternate layers of both
components.


Material
• A suspension of finely grounded materialalumina(slip) is mixed to a
thin,creamy,consistency,is brushed onto the
die in a method slipcasting.
• Water is removed via the capillary action of
porous gypsum which packs the particles into
a rigid network.Initial grain size –3microns.

• It is fired at a temperature rise of approx 20
C /min to 1120 C for 2 hrs.
• This causes approx of particles with minimal
compaction and minimal shrinkage(minimal
sintering) of alumina forming a porous network.
• It has chalky consistency and still easy to
process.

• Lathanum alumino silicate La(Al2O3 SiO2)
glass is used to infiltrate the pores by
capillary action at high temperature.
• Veneered with compactabile feldspathic
porcelain.


Properties
• Flexural strength:-600 Mpa.
• Infused alumina core is 2.5 times stronger
than glass ceramic and feldspathic
porcelain.
• Posess greater compressive strength than
IPS empress but less than metal ceramic
restorations.
• Fracture toughness-4.7 Mpa.

Advantages
• Lack of metal substructure.
• Very high flexural strength.
• Excellent fit.


Disadvantages
• Opacity of core.
• Unsuitable for conventional acid etching.
• Need for specialised equipment.


INCERAM ZIRCONIA
• PRINCIPLE:
•
Strengthening is achieved by
incorporating a crystalline material that is
capable of undergoing a change in crystal
structure when placed under stresess &
provides higher strength.


• Material incorporated is 33%
zirconia(partially stabilized zirconia).
• 1.To improve flexural strength,fracture
toughness and fatigue resistance.
• 2.The energy required for transformation of
PSZ is taken from energy that allows the
crack to propagate.

Properties
• Flexural strength is 700MPa
• Greater strength-can be used for posterior
bridges.
• Moderate transluency.
• Biocompactible and good tissue response.
• Fracture toughness is 6.8MPa.
• Refractive index of PSZ > than surrounding
glass matrix.

INCERAM SPINELL
• A second generation material based on inceram
technique.
• A primary difference is a change in composition to
produce a more translucent core.
• Porous core is fabricated from magnesium –
alumina after sintering.It has special crystalline
structure referred to as ‘SPINEL’[magnesium
aluminate,MgAl2O4].

• Originally magnesium oxide and aluminium
oxide were mixed in a ratio of 1:1 and
transformed to spinel at temp above 1600 C.
• Porous spinel is secondarily infused with
glass which produces a more translucent
substructure upon which vitadur alpha is
placed to form final restoration.

Properties
• Weaker but more translucent than the
alumina core-recommended for esthetically
challenging single unit anterior restoration.
• Flexural strength=350 Mpa.
• Fracture toughness=2.7 Mpa
• Acid resistant,chemical stability,low
electrical conductivity,high transluency and
biocompactible.

MACHINABLE CERAMICS
• These products are supplied as ingots in various
shades & are milled into desired form.These
machine restorations can be stained & glazed to
obtain desired characterisation.
• They are 2 types:• 1.CADCAM-Computer aided designing computer
aided milling.
• Example: CEREC(sirconia)
•
Ivoclar proCAD(Ivoclar)
•
Dicor MGC(Dentsply)
• 2.Copy milling:Celay(michrono technologies)

CADCAM CERAMIC
• A machinable ceramic material formulated
for the production of inlays and crowns
through the use of a computer aided
design,computer aided machining process.
• Eg:Cerec,cerec2,cerec3,cerec scan,cerec
inlab,procera.


History
• Development of CADCAM systems for the dental
profession began in
•
1970s with Duret in France,Altschuler in
USA, Mormann and Brandestini in Switzerland.
•
Rekow-1987
•
William-1987
•
Rekow et al-1992-93
•
Rice & Mecholsky-1997
•

Objectives
• To eliminate traditional impressional
methods.
• To design, with aid of the computer, the
future restoration is accordance with the
preparation, the function and natural
anatomy.
• To produce the restoration chairside.

• To machine the restoration by rotating
device,sono or electro-erosion,laser etc..
• To improve restoration qualities-mechanical
resistance,marginal fit,surface qualities and
esthetics.


Advantages
• Negligible porosity in CADCAM core
ceramics.
• Freedom from making impression.
• Need for only single appointment.
• Good patient acceptance.


• Need for costly equipments.
• Lack of computer controlled processing
support for occlusal adjustment.
• Technique sensitive.


Types of CADCAM
• Direct : Fully integrated CADCAM devices
for chairside restorative approach.
• CADCAM stations are located at the dental
office.


• Indirect method: It consists of several
modules with at least distinctive
CAD&CAM stations.
• The impression(optical) is taken in the
dental office where the CAD operation is
carried out.Data are transmitted to central
CAM station for restoration manufacturing.

• Optical impression is taken in the dental
office, collected information is then
transmitted to a central station where
CAD&CAM modules operate.
•


• Because of overall dimension and cost of
the CADCAM machines, they are usually
not located in a dental office,but more likely
in a different treatment places converge.
•
eg:Duret system
•
procera[Nobel biocare]
•
cicero system[elephant industries]
•
president DCS system[DCS dental].

DIRECT CADCAM System
• CEREC system has been marketed for
several years with the improved CEREC2
introduced in mid-1990’s and upgraded to
CEREC3 in 2000.
• The equipment consists of a computer
integrated imaging and milling system, with
the restoration designed on the computer
screen.

MATERIALS USED
• Vita Mark II [Vident]:contains
sanidine[KALSi3O8] as a major crystalline
phase with a glassy matrix.
• Dicor MGC:is a mica based machinable
glass ceramic that contain 70 vol% of
crystalline phase.


• The unique “HOUSE OF
CARDS”microstructure found in Dicor
MGC is due to interlocking of the small
platelet shaped mica crystals with an
average size of 1-2 microns.
• It leads to multiple crack deflection and
ensures a greater strength than leucite
containing ceramics.

• ProCad[ivoclar]: is a leucite containing
ceramic.


• Vita Inceram Blocks [Vita Zahnfabrik]:
• SPINEL blanks: Spinel are used for to
obtain an esthetically appealing, translucent
ceramic structures.
• ALUMINA blanks:this has the advantage of
the synthetic corundum that is prepared
from bauxite in electric melting furnance.

• ZIRCONIA blanks: this combines the
fracture toughness of the metastable
tetragonal zirconium oxide referred to an
ceramic steel.


LIMITATION IN CEREC
• The cerec system was acceptable with
regard to the longetivity of adhesively
bonded restoration , but the amount of
manual correction to make material fit was
too high.
• Poor marginal fit of restoration.


• Diamond disc was only tool for
cutting.Hence it was important to
incorporate an additional diamond cutting
instrument.
• Lack of sophistication in machining of
occlusal surface.


• Dentist’s required intensive training for
CAD.So it was important to achieve easy
and user friendly software for CAD.


CEREC 2:Improvisations in
cerec 2
• Improvisations were made in CEREC2 such
as
• 1.CAD module was implemented with a
second form milling tool(a
cylindrical,diamond bur) which provides six
milling axes instead of three.
• 2.It has enchanced control software.

• 3.New camera provides more data with
greater accuracy with a resolution from 2550 microns.
• 4.It is capable of processing much more
complicated restoration form & roughly
developing occlusal surface.
• 5.Marginal adaptation of CEREC2 is
improved.

CEREC3
• Software still easy & user friendly which
uses window as operating systems.
• Precise restoration.
• External & internal measuring.
• Rapid production.
• Imaging unit & milling unit can be linked
via various means.
• Supported with online helps & design.

Advantages
•
•
•
•

Time saving-one or two appointments required.
Time taken for making optical impression is 5 sec.
Wear hardness similar to enamel.
Less fracture due to the usage of single
homogenous block with negligible porosity.
• Excellent polish & improved esthetics.
• Good occlusal morphology.

INDIRECT CADCAM
• Eg: Cerec scan,cerec inlab,procera system.
• CEREC SCAN:
•
Inclusive of both scaning &
milling device with laptop imaging device.
•
•


• CEREC INLAB:
•
Consists of a compact milling
unit with a in built scanner.It produces more
precision restoration.Software runs as
WINDOW 98.


• Procerra system:
•
Introduced by Dr.Matts
Anderson from Nobel Biocare.
•
Involves an industrial
CAD/CAM process.


Materials used
• Involves(densely sintered high purity
inmdustrial aluminum oxide) core
combined with a (low fusing veneering
porcelain) fabricated by the pressed powder
technique.


Technique Specification
• Computer aided designed copings of 0.2mm
thickness is made from dense sintered
industrial aluminium oxide with is
translucent & tooth colored.
• Final morphology constructed with
aluminium ceramic with matched thermal
expansion.

Advantages
•
•
•
•
•
•

Good clinical perfomance.
Good marginal adaptation.
Metal free & precision fit.
Reduced opposing wear.
Natural translucency & biocompactibility.
Enhanced esthetic & strength

Indication
• All single crown anterior & posterior for modified
implant copings for direct cementation.
• Where minimum crown thickness only possible &
light transmission through to the gingiva for good
esthetics is critical.
• In situation where good moisture control is
difficult & adhesive luting technique is
contraindicated.

Copy milling
• A process of machining a structure using a
device that traces the surface of a master
metal, ceramic or polymer pattern &
transfers the traced spatial positions to a
cutting station where a blank is cut or
ground in a manner similar to a key-cutting
procedure.
• Eg:Celay

CELAY Systems(Mikrona
technologies)
• Developed by Dr.Stefan I.Eidenbenz at the
university of Zurich in 1994.
• It is a precision copy milling machine that
uses similar types of ceramic materials,but
is not computer driven.


Technique Specification
• Based on a mechanical device that is used to trace
the surface of a prefabricated pattern of the
designed restoration made from a blue resin based
composite which is produced either directly on die
made from impression.
• Replica is mounted on one side of celay
system(scanning side)and a ceramic block is
mounted on the milling side.


• Uses sequential milling procedure
proceeding from course to fine milling bur.
• Restoration are milled in 15-20min with
internal & occlusal surfaces fully formed.


Materials Used
• Vitablocks similar to CEREC vitablocks.
• Inceram alumina blocks are used to fabricate
single and multiple unit.
• Inceram cores for production of all ceramic
crowns & bridges.
• Inceram porous alumina is milled with the celay
system & subsequently infused with glass before
application of the overlying porcelain

ADVANTAGES
• Marginal accuracy seem to be good, a little
better than the cerec system.
• Less adjustment work.


HOT PRESSED, INJECTION
MOULDED CERAMIC
• They are supplied as ingots.
• These products are melted at high
temperature and injected into a moulded
using lost wax process.
• They can be made into full contours or used
as a substrate for conventional feldspathic
porcelain buildup or layering technique.

• Example:
•
IPS Empress I,II [Ivoclar vivadent[
•
OPC
•
Alceram[ cerestore, innotek dental
corporation].


IPS EMPRESS
• Leucite reinforced glass ceramic material
[40%-50%]
• Leucite crystals increase the strength and
fracture resistance of the feldspathic glass
matrix.


COMPOSITION
•
•
•
•
•
•
•
•
•
•

SiO3-59%-63%
K2O-10%-14%
Al2O3-17%-21%
CeO3-0.1%
Na3O-3.5%-6.5%
BaO-0-1.5%
B2O3-0.1%
CaO-0.5%-2.8%
TiO3-0.05%
PIGMENT-0.5-1%

TECHNIQUE
• Restoration is first waxed up and invested using
the lost wax process.
• Ingots are softened before being pressed into a
mould under pressure of 0.4MPa at 1150 C.
• Pressure maintained for 20 min during which time
the tetragonal leucite crystals are dispersed
throughout the restoration, giving a 40%
concentration by volume.

Advantages
• Lack of metal or opaque ceramic core
• Moderate flexural strength [similar to that
of Optec HSP]
• Excellent fit and esthetics.
• Increased durability and wear
compactibility
• High transluency and natural esthetics.

Disadvantages
• Potential for fracture in posterior region.
• Need for special laboratory equipment.


PROPERTIES
•
•
•
•

Bending fatigue strength:200MPa.
Marginal gap width:50 microns.
Flexural strength:220MPa.
Marginal integrity:<50 microns.


INDICATION
• Inlaysonlays
• Veneers.
• Full coverage crowns.


IPS EMPRESS 2
• Principle:
•
increasing the strength of the
material without compromising its
transluency.
• High strength of IPS Empress2 replaces
older IPS Empress.


MATERIAL
• Schwieger et al developed a highly
crystalline [>60%] microstructure of
densely arranged lithium disilicate crystals
of size 0.5-5 microns were uniformly
bonded in a glassy matrix.
• It is composed of homogenously shaped
elongated lithium disilicate crystals
arranged in a interlocking structure.

• This hinders crack propogation to elevate
fracture toughness and flexural strength.
• In addition to lithium disilicate ,lithium
ortho phosphate occurs as a secondary
crystal phase measuring 0.1-0.3 microns
which are comparatively small.


COMPOSITION
•
•
•
•
•
•
•
•
•

SiO3-57-80%
Al2O3-0-5%
La2O3-0.1-6%
MgO-0-5%
ZnO-0-8%
K2O –0-13%
Li2O3-11-19%
P2O3-0-11%
Pigment-0-8%m

Layering ceramic
• Sintered glass ceramics.
• Supplied in powder form- dentin
,incisal,transparent.
• Their crystalline phase consist of
fluoroapatite.


COMPOSITION
•
•
•
•
•
•
•
•

SiO3
-45-70%
Al2O3
-5-22%
P2O3
-0.5-6.5%
K2O
-3-9%
Na2O
-4-13%
CaO
-0-11%
F
-0.1-2.5%
PIGMENT-0.3%

Indication
• Anterior and posterior crowns and bridges.


ALCERAM
• MATERIAL:
•
Aluminium oxide and magnesium oxidereact to form magnesium aluminate spinel
(MgAl2O4).
• Magnesium aluminate spinel occupies a greater
volume than the combination of magnesium oxide
and aluminium oxide, the resultant volume
increase compensate for the firing shrinkage
(starling et al).
• Non shrink ceramics.

COMPOSITION
•
•
•
•
•
•
•
•
•

Al2O3
Al2O3
BaO-SiO2-Al2O3 GLASS FRIT
(58%BaO,42%SiO2,5%Al2O3)
MgO
Edger plastic kaolin
Calcium stearate
Accrawax
Silicone resin

-43.29%
-17.32%
-12.99%
-8.66%
-3.90%
-0.86%
-0.86%
-12.12%

• Calcium stearate and accrawax- binder and
lubricant.
• Barium glass frit and silicon resin –forms glass
phase.
• On temperature over 1300 C the magnesium and
some alumina combine to form spinel.
• Crystal content of ceramic-70%-95% by body wt.


• Cerestore coping is placed on the master die
and a suitable aluminous veneer porcelain is
used to complete the crown


PROPERTIES
•
•
•
•

Density-2.80gcc
Flexural strength-125MPa
Compressive strength-450MPa
Low coefficiet of thermal expansionbelow8*10-6 C.


Thank you
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Metal free ceramics /certified fixed orthodontic courses by Indian dental academy

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