9.biomaterials in dental implants /orthodontic courses by Indian dental academy

INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTS
INTRODUCTION
TERMINOLOGIES
HISTORY
CLASSIFICATION OF BIOMATERIALS

BIOCOMPATIBILITY
CORROSION RESISTANCE
CYTOTOXICITY OF CORROSION
PRODUCTS
METAL CONTAMINATION
BIOFUNCTIONABILITY

INDIVIDUAL MATERIALS
METALS AND ALLOYS
CERAMICS AND CARBON
POLYMERS AND COMPOSITE
POLYMERS

SURFACE MODIFICATIONS
CONCLUSION
REFERENCES

TERMINOLOGIESTERMINOLOGIES
BiocompatibilityBiocompatibility – (– (Dorland'sDorland's illustrated medicalillustrated medical
dictionary)dictionary) Being harmonious with life and not havingBeing harmonious with life and not having
toxic or injurious effects on biofunction.toxic or injurious effects on biofunction.
BiomaterialBiomaterial – Any substance other than drug that can be– Any substance other than drug that can be
used for any period as a part of a system that treats,used for any period as a part of a system that treats,
augments or replaces any tissue, organ or function of theaugments or replaces any tissue, organ or function of the
body.body.

BiotolerantBiotolerant – Material that is not necessarily rejected– Material that is not necessarily rejected
but are surrounded by fibrous layer in the form of abut are surrounded by fibrous layer in the form of a
capsule.capsule.
Bio inertBio inert – Material that allows close apposition of– Material that allows close apposition of
bone on their surface, leading to contact osteogenesis.bone on their surface, leading to contact osteogenesis.
BioactiveBioactive - Materials that allow formation of new bone- Materials that allow formation of new bone
onto their surface, but ion exchange with host tissueonto their surface, but ion exchange with host tissue
leads to formation of a chemical bond along theleads to formation of a chemical bond along the
interface (interface (bonding osteogenesisbonding osteogenesis).).

OsteoconductiveOsteoconductive – the materials that forms– the materials that forms
scaffolding that allows the formation of bone.scaffolding that allows the formation of bone.
OsteoinducitiveOsteoinducitive – materials that have capacity– materials that have capacity
to induce bone formation de novo.to induce bone formation de novo. E.gE.g.-.-
recombinant human bone morphogeneticrecombinant human bone morphogenetic
protein 2.protein 2. (rhBMP-2)(rhBMP-2)

2500 BC2500 BC - Ancient- Ancient
Egyptians -Egyptians - goldgold
ligature.ligature.
500 BC500 BC - Etruscan- Etruscan
population -population - goldgold
bands incorporatingbands incorporating
pontics.pontics.

500 BC500 BC - Phoenician- Phoenician
population -population - goldgold wire.wire.
300 BC300 BC - Phoenician- Phoenician
population - Carvedpopulation - Carved
IvoryIvory teeth.teeth.

600 AD600 AD - Mayan- Mayan
population - implantationpopulation - implantation
of pieces ofof pieces of shell.shell.
17001700 - John Hunter -- John Hunter -
transplantingtransplanting the teeth.the teeth.

18091809 - Maggiolo -- Maggiolo -
pieces ofpieces of gold.gold.
1911 -1911 - Greenfield -Greenfield -
iridoplatinumiridoplatinum basketbasket
soldered with 24 caratsoldered with 24 carat
gold.gold.

19391939 - Strock -- Strock -
vitalliumvitallium screw toscrew to
provide anchorage forprovide anchorage for
replacement.replacement.
19401940 - Formiggini -- Formiggini -
spiral implant -spiral implant -
stainless steelstainless steel wire.wire.

1943 - Dahl -Subperiosteal
type of implant.
1948 - Goldberg and
Gershkoff - Extension of
frame work.

EarlyEarly 19601960s - Chercheve -s - Chercheve -
Double helical SpiralDouble helical Spiral
implant ofimplant of CobaltCobalt
Chromium.Chromium.
EarlyEarly 19701970s - Grenoble -s - Grenoble -
Vitreous CarbonVitreous Carbon implants.implants.

EarlyEarly 19801980s - Tatum -s - Tatum -
TitaniumTitanium root formroot form
implantimplant
LateLate 19701970s and Earlys and Early
1980s - Tatum -1980s - Tatum -
custom blade implantscustom blade implants
ofof TitaniumTitanium alloyalloy

19701970 andand 19801980 - Weiss- Weiss
and Judy -and Judy - TitaniumTitanium
Mushroom shapedMushroom shaped
projection (IMPLANT)projection (IMPLANT)

After 1980s –hollow basket Core vent implant
Screw vent implant
Screw vent implant with Hydroxyapatite coating
implant with titanium plasma spray

BiologicalBiological
biocompatibilitybiocompatibility
Chemical compositionChemical composition
MetalsMetals CeramicsCeramics PolymersPolymers
BiotolerantBiotolerant GoldGold PolyethylenePolyethylene
Cobalt-chromiumCobalt-chromium
alloysalloys
PolyamidePolyamide
Stainless steelStainless steel PolymethylmethacrylatePolymethylmethacrylate
ZirconiumZirconium PolytetrafluoroethylenePolytetrafluoroethylene
NiobiumNiobium PolyurethanePolyurethane
TantalumTantalum
BioinertBioinert Commercially pureCommercially pure
titaniumtitanium
Aluminum oxideAluminum oxide
Titanium alloy (Ti-Titanium alloy (Ti-
6Al-4V)6Al-4V)
Zirconium oxideZirconium oxide
BioactiveBioactive HydroxyapatiteHydroxyapatite
TricalciumTricalcium
phosphatephosphate
CalciumCalcium
pyrophosphatepyrophosphate
FluorapatiteFluorapatite
Carbon:vitreous,Carbon:vitreous,
pyrolyticpyrolytic
BioglassBioglasswww.indiandentalacademy.comwww.indiandentalacademy.com

 Corrosion resistance
 Cytotoxicity of corrosion products
 Metal contamination

Corrosion - It is defined as loss of metallic ions
from the surface of the metal to the
surrounding environment.
Types of corrosion :
General Galvanic
Pitting Fretting
Crevice Stress
corrosion cracking

General corrosion - When metal is immersed in
electrolytic solution the positively charged ions
from the metal are transferred to electrolyte and
then metal transports the negatively charged
electrons.

Pitting corrosion - Along with general corrosion on
the surface there is enhanced corrosion in the pit.

Crevice corrosion -The local environment around the
screw to bone plate interface or implant device. Where
in overlay or composite type surface exists on a
metallic substrate. They provide opportunities for
crevice corrosion.

Galvanic corrosionGalvanic corrosion – It occurs when two dissimilar– It occurs when two dissimilar
metallic materials are in contact in a electrolyte leading tometallic materials are in contact in a electrolyte leading to
flow of current.flow of current.

Fretting corrosionFretting corrosion – It occurs when there is a micro-– It occurs when there is a micro-
motion and rubbing contact within the corrosivemotion and rubbing contact within the corrosive
environment.environment.

Stress corrosion crackingStress corrosion cracking – The combination of– The combination of
high mechanical stresses and simultaneoushigh mechanical stresses and simultaneous
exposure to a corrosive environment results inexposure to a corrosive environment results in
the failure of metallic materials by crackingthe failure of metallic materials by cracking
where neither condition alone would cause thewhere neither condition alone would cause the
failure.failure.

PROTECTION AGAINST CORROSION
Passivation
Increasing the noble metal content
Polishing the surface
Avoid dissimilar metal contact

CYTOTOXICITY OF CORROSION PRODUCTS
 The material should undergo only minimal amount of
biochemical changes during service.
 The material should have minimal reaction with the
surrounding bone and the soft tissue.
 Ideally the corrosion products should not produce any
toxicity to the local and systemic environment.

METAL CONTAMINATION
By contacting dissimilar metals or alloys. The debris
from the dissimilar metals can be embedded in the
implant surface and corrode to form compounds that
cause foreign body reactions in the surrounding tissue.

Two different metals in the saline solutions or body fluids
may result in a localized difference of electrochemical
potential and cause galvanic corrosion. So the instruments
that contact titanium implant during insertion procedures
either be solid titanium, titanium tipped or treated to
prevent metallic transfer.
During storage, sterilization and surgical set up no other
type of metal should contact the implant surface.

PHYSICAL AND MECHANICAL PROPERTIESPHYSICAL AND MECHANICAL PROPERTIES
The macroscopic distribution of mechanical stress
and strain is predominantly controlled by the shape
and form of the implant.
The microscopic distribution is controlled by the
Basic properties of biomaterials as -Surface
chemistry, Microtopography, Modulus of elasticity
and Surface attachment to the adjacent tissue.

The dental implant are less affected by alternating
stresses than implants of cardiovascular and
locomotive systems because of lower number of
loading cycles and considerable smaller size of
implants.
But in cases with Para functional habits the longevity
is detrimental.

The forces exerted on implant consists of compressive
tensile and shear. As for the most of the materials
compressive force is greater than others.
Basic problem lies due to the difference in mechanical
strength and deformability of the material and the
recipient bone.

The metals can be modified to achieve the required
properties by work hardening or alloying.
The ability of the implant to bear the stress decreases
as the number of loading cycles increases. Higher the
applied load higher the mechanical stress greater the
possibility of exceeding the fatigue limit of the
material.
Many materials are biocompatible but cannot be used
as an implant because of their low ultimate strength.

MODULUS OF ELASTICITYMODULUS OF ELASTICITY
It representsIt represents elastic responseelastic response of an implant to theof an implant to the
mechanical stress.mechanical stress.
The forces applied on the implant leads to stresses withinThe forces applied on the implant leads to stresses within
the bone.the bone.
When the applied forces are equal to stresses it acquiresWhen the applied forces are equal to stresses it acquires
thethe state of static equilibriumstate of static equilibrium..

When the forces increase, it leads to deformation.When the forces increase, it leads to deformation.
The physiologic importance of modulus of elasticityThe physiologic importance of modulus of elasticity
of biomaterial is related to the modulus of elasticityof biomaterial is related to the modulus of elasticity
of the bone.of the bone.
The degree of relative movement at the interfaceThe degree of relative movement at the interface
determines the health or pathologic state of interface.determines the health or pathologic state of interface.

The modulus of elasticity ofThe modulus of elasticity of titanium is very near totitanium is very near to
bone compared to any other materialbone compared to any other material used.used.
It is almostIt is almost 6 times more stiff than dense cortical bone.6 times more stiff than dense cortical bone.
The carbon implants has compatible stiffness with boneThe carbon implants has compatible stiffness with bone
but fail to have adequate strengthbut fail to have adequate strength to withstandto withstand
physiologic load leading to microcracks and finally thephysiologic load leading to microcracks and finally the
failure of implant.failure of implant.

On the other hand theOn the other hand the aluminum oxidealuminum oxide
ceramic implant has high ultimate strengthceramic implant has high ultimate strength
but thebut the stiffness is 33 times greater than thestiffness is 33 times greater than the
stiffness of the bonestiffness of the bone which results in apparentwhich results in apparent
stress shielding of interfacial bone.stress shielding of interfacial bone.

The modulus of elasticity in subperiosteal implants not
as important a consideration. The envelopment of the
implant in the outer layer of periosteum during healing
provides a stable biomechanical situation.

For bilateral/total subperiosteal implant may cause
excessive relative movement due to its rigidity. So
cutting these at the midline or providing individual
abutment can increase flexibility.
For unilateral subperiosteal implant the negative effect
of relative movement of metal is minimal.

Materials Science & Engineering Dept.
Research Experience for Undergraduates

Most of the materials used for implants are constructedMost of the materials used for implants are constructed
from metals and their alloys. These includesfrom metals and their alloys. These includes TitaniumTitanium,,
Tantalum, Aluminum, Vanadium, Cobalt, Chromium,Tantalum, Aluminum, Vanadium, Cobalt, Chromium,
Nickel and MolybdenumNickel and Molybdenum. These are selected on the basis. These are selected on the basis
of their over all strength. Less frequently used areof their over all strength. Less frequently used are
precious metals asprecious metals as GoldGold andand Platinum.Platinum.

The evolution of titanium (Ti) applications
to medical and dental implants has
dramatically increased in the past few years
because of titanium’s excellent
biocompatibility corrosion resistance and
desirable physical and mechanical
properties.
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Titanium has become a material of great
interest in prosthodontics in recent years. A
growing trend involves the use of titanium
as an economical and biocompatible
replacement for existing alloys.

The physical and mechanical properties of pure Ti
and Ti alloys can be greatly varied with the
addition of small traces of other elements such as
oxygen, iron, and nitrogen.
Commercially pure titanium, is available in four
different grades

ASTM I to 1V - based on the incorporation
of small amounts of oxygen, nitrogen,
hydrogen, iron, and carbon during purification
procedure.
ASTM committee on materials for surgical
implants recognizes four grades of
commercially pure titanium and two titanium
alloys.

The two alloys are Ti-6Al-4V and Ti-6A1-4V
extra low interstitial (ELI).
Commercially pure titanium is also referred to
as unalloyed titanium. All six of these
materials are commercially available as dental
implants.

Ti-6A1-4V
Several alloys of titanium are used in
dentistry. Of these alloys, Ti 6Al-4V is the
most widely used.
At room temperature, Ti-6A1-4V is a two-
phase α+β alloy.
At approximately 975°C, an allotropic phase
transformation takes place, transforming the
microstructure to a single phase BCC β-alloy.

Thermal treatments dictate the relative
amounts of the α and β phases and the phase
morphologies and yield a variety of
microstructures and a range of mechanical
properties.

PRODUCTION MACHINING AND AUTOCLAVING

Mechanical PropertiesMechanical Properties
The modulus of elasticity of CpTi - 104 MpaThe modulus of elasticity of CpTi - 104 Mpa
Ti alloyTi alloy -113 Mpa.-113 Mpa.
The yield strength of CpTi - 860 MpaThe yield strength of CpTi - 860 Mpa
Ti alloyTi alloy – 745 Mpa.– 745 Mpa.
The strength ofThe strength of Ti alloyTi alloy is 2-4 times CpTi.is 2-4 times CpTi.
The modulus of elasticity is increased from 104 Mpa toThe modulus of elasticity is increased from 104 Mpa to
113 Mpa113 Mpa.. www.indiandentalacademy.comwww.indiandentalacademy.com

Compared to Bone - modulus of elasticity ofCompared to Bone - modulus of elasticity of
CpTi is 5 times and Ti alloy is 5-6 times.CpTi is 5 times and Ti alloy is 5-6 times.
Compared to Co-Cr-Mo these are twice strongCompared to Co-Cr-Mo these are twice strong
and ½ the elastic modulusand ½ the elastic modulus
Has poor shear strength and wear resistance soHas poor shear strength and wear resistance so
unsuitable for holding bone screws.unsuitable for holding bone screws.

OXIDE COATINGSOXIDE COATINGS
The Biocompatibility of the Ti and Ti alloy is attributed toThe Biocompatibility of the Ti and Ti alloy is attributed to
the ability of formation of passive tenacious surface oxide.the ability of formation of passive tenacious surface oxide.
Minimum of 85 to 95% of pure titanium is required toMinimum of 85 to 95% of pure titanium is required to
maintain passivity.maintain passivity.
The pure titanium theoretically may form several oxides asThe pure titanium theoretically may form several oxides as
TiO, Ti OTiO, Ti O2,2,TiTi22OO3.3.
The oxides form spontaneously on exposure to Ti to air.The oxides form spontaneously on exposure to Ti to air.

Within a millisecond 10Within a millisecond 10Å thick oxide layer will beÅ thick oxide layer will be
formed. In a minute the layer will become 100Å thick.formed. In a minute the layer will become 100Å thick.
The repair of the oxide layer is instantaneous if anyThe repair of the oxide layer is instantaneous if any
damage occurs during insertion of Implant.damage occurs during insertion of Implant.
Rate of dissolution is extremely low compared to anyRate of dissolution is extremely low compared to any
implant metals.implant metals.

Cobalt Chromium Molybdenum AlloyCobalt Chromium Molybdenum Alloy
High modulus (stiffness) and Low ductility.High modulus (stiffness) and Low ductility.
Outstanding resistance to corrosionOutstanding resistance to corrosion
Excellent biocompatibilityExcellent biocompatibility
Commonly used for fabrication of custom designCommonly used for fabrication of custom design
(e.g. : subperiosteal frames) by casting.(e.g. : subperiosteal frames) by casting.

Composition:Composition:
63% cobalt 30% Chromium – for passivation63% cobalt 30% Chromium – for passivation
5 % Molybdenum – Strength5 % Molybdenum – Strength
Traces of carbon , magnesium, and nickelTraces of carbon , magnesium, and nickel
Precautions:Precautions:
Proper fabrication techniques should be usedProper fabrication techniques should be used
Poor ductility so bending can be avoided so cannot bePoor ductility so bending can be avoided so cannot be
used form blade for implants.used form blade for implants.

IRON - CHROMIUM - NICKEL BASED ALLOYSIRON - CHROMIUM - NICKEL BASED ALLOYS
Surface is passivated to increase biocorrosion resistance.Surface is passivated to increase biocorrosion resistance.
High strength and ductility.High strength and ductility.
Used in wrought and heat treated condition.Used in wrought and heat treated condition.
Composition (Surgical austentite steel)Composition (Surgical austentite steel)
18% chromium - for corrosion resistance.18% chromium - for corrosion resistance.
8% nickel - to stabilize austentic structure.8% nickel - to stabilize austentic structure.
0.5% carbon - as hardener.0.5% carbon - as hardener.

PrecautionsPrecautions
Contraindicated in patients sensitive to nickel.Contraindicated in patients sensitive to nickel.
Most susceptible toMost susceptible to crevice and pitting corrosioncrevice and pitting corrosion, so care, so care
to be taken to preserve passivated surface.to be taken to preserve passivated surface.
Has galvanic potential, so avoid contact with dissimilarHas galvanic potential, so avoid contact with dissimilar
metal.metal.

Other Metals and AlloysOther Metals and Alloys
Gold, Platinum, Iridium and alloys of these metals are beingGold, Platinum, Iridium and alloys of these metals are being
used.used.
Have low strength that limits the implant design.Have low strength that limits the implant design.
High cost and High density.High cost and High density.
Due to its nobility and availability gold is continued to beDue to its nobility and availability gold is continued to be
used as surgical Implant materials.used as surgical Implant materials.

Ceramics and Carbon as implant MaterialsCeramics and Carbon as implant Materials
CERAMICSCERAMICS
These areThese are non organic,non organic, non metallic,non metallic, non polymericnon polymeric
materials manufactured by compacting and sintering atmaterials manufactured by compacting and sintering at
elevated temperatures.elevated temperatures.

These are bio compatible high strength insulators.These are bio compatible high strength insulators.
Have low ductility and inherent brittleness are theirHave low ductility and inherent brittleness are their
limitations.limitations.
Classified into :Classified into :
Bio activeBio active -Ca-Ca33(PO(PO44), Hydroxyapatite), Hydroxyapatite
Bio non-reactiveBio non-reactive - Oxides of Aluminum, Titanium,- Oxides of Aluminum, Titanium,
ZirconiumZirconium

ALUMINUM, TITANIUM, ZIRCONIUM OXIDESALUMINUM, TITANIUM, ZIRCONIUM OXIDES

Used for Endosteal root form, plateUsed for Endosteal root form, plate
form implantsform implants

Have clear white cream or light greyHave clear white cream or light grey
color so used for anterior root formcolor so used for anterior root form

Minimal biodegradationMinimal biodegradation

High modulus of elasticityHigh modulus of elasticity

Low fracture resistanceLow fracture resistance

Exhibit direct interface with boneExhibit direct interface with bone
THE TÜBINGEN IMPLANT OF ALUMINUM OXIDE HAS
SPECIFIC MICRO-IRREGULARITIES ON THE SURFACE,
CLAIMED TO ALLOW BONE INGROWTH.

DISADVANTAGESDISADVANTAGES
Exposure to steam sterilization results in measurableExposure to steam sterilization results in measurable
decrease in strength of some ceramics. So dry heatdecrease in strength of some ceramics. So dry heat
sterilization is recommended.sterilization is recommended.
Scratches or notches may induce fracture initiatingScratches or notches may induce fracture initiating
sites.sites.
Although initial testing showed adequate mechanicalAlthough initial testing showed adequate mechanical
strengths, long term clinical results clearlystrengths, long term clinical results clearly
demonstrate a functional design and material relateddemonstrate a functional design and material related
limitations.limitations.

BIOACTIVE AND BIODEGRADABLE CERAMICSBIOACTIVE AND BIODEGRADABLE CERAMICS
Calcium Phosphate CeramicsCalcium Phosphate Ceramics
The compositions was relatively similar to bone CaThe compositions was relatively similar to bone Ca55(PO(PO44))33OHOH
Color similar to bone.Color similar to bone.
Shows good bonding with bone so it can be used whenShows good bonding with bone so it can be used when
structural support is required under high magnitude loading.structural support is required under high magnitude loading.

Mixtures with collagen, active organicMixtures with collagen, active organic
compounds as bone morphogenetic proteinscompounds as bone morphogenetic proteins
and with drugs have increased the range of itsand with drugs have increased the range of its
applications.applications.
It is used as a coating over the metallic implants.It is used as a coating over the metallic implants.
Modulus of elasticity is very near to bone.Modulus of elasticity is very near to bone.

Low mechanical tensile and shear strengths underLow mechanical tensile and shear strengths under
fatigue loading.fatigue loading.
Low attachment strength on some substrates.Low attachment strength on some substrates.
Variable solubility depending on the product andVariable solubility depending on the product and
their clinical applications.their clinical applications.

HYDROXYAPATITEHYDROXYAPATITE
When the calcium and phosphorus in the ratio of 1.5When the calcium and phosphorus in the ratio of 1.5
to 1.7 are sintered in water containing atmosphereto 1.7 are sintered in water containing atmosphere
at 1200at 1200ººC to 1300C to 1300ººC a crystallographic endC a crystallographic end
product will be obtained that isproduct will be obtained that is HydroxyapatiteHydroxyapatite..
This hasThis has osseoconductive effectosseoconductive effect when comes inwhen comes in
contact with bone.contact with bone.

Hydroxyapatite is non porous with angular orHydroxyapatite is non porous with angular or
spherical shape particles that are examples ofspherical shape particles that are examples of
crystalline high purecrystalline high pure HydroxyapatiteHydroxyapatite..
Their compressive strength is 500 Mpa and tensileTheir compressive strength is 500 Mpa and tensile
strength is 50-70 Mpa.strength is 50-70 Mpa.

PROPERTIES OF BIOACTIVE CERAMICSPROPERTIES OF BIOACTIVE CERAMICS
Dense polycrystalline ceramics with small crystallites haveDense polycrystalline ceramics with small crystallites have
higher mechanical strengthhigher mechanical strength..
These ceramics are widely used as coatings on metallicThese ceramics are widely used as coatings on metallic
implant substratesimplant substrates..

Calcium phosphate ceramics have become a routine useCalcium phosphate ceramics have become a routine use
byby plasma spray techniqueplasma spray technique..
This techniqueThis technique increases the surface areaincreases the surface area which in turnwhich in turn
increases theincreases the osseointegrationosseointegration..

Density, Conductivity and SolubilityDensity, Conductivity and Solubility
Density of the material increases as the percentage ofDensity of the material increases as the percentage of
crystallinity increases.crystallinity increases.
As the density / crystallinity increases the solubilityAs the density / crystallinity increases the solubility
decreases.decreases.
The solubility also depends on the surface area.The solubility also depends on the surface area.

The amorphous products are more solubleThe amorphous products are more soluble
because they have less organized atomicbecause they have less organized atomic
structure.structure.
These are susceptible to enzyme or cell mediatedThese are susceptible to enzyme or cell mediated
breakdown in the same way that of livingbreakdown in the same way that of living
bone.bone.
These are non conductors of heat and electricity.These are non conductors of heat and electricity.

The Ceramic implant surface responds to the localThe Ceramic implant surface responds to the local
pH changes by releasing Na, Ca, P and Si ions inpH changes by releasing Na, Ca, P and Si ions in
exchange for Hexchange for H22 ions.ions.
Si reacts with OSi reacts with O22 to formto form Silica gel. As the. As the
concentration of phosphorus and calciumconcentration of phosphorus and calcium
increases at the surface they combine to formincreases at the surface they combine to form
calcium phosphate rich layer and the collagencalcium phosphate rich layer and the collagen
fibers become incorporated into it.fibers become incorporated into it.
TISSUE RESPONSETISSUE RESPONSE

This way the functional integration with bone occursThis way the functional integration with bone occurs
with the help of natural bone cementing substancewith the help of natural bone cementing substance
so the bond formed is strong.so the bond formed is strong.

CARBON AND CARBON SILICON COMPOUNDSCARBON AND CARBON SILICON COMPOUNDS
Extensive applications forExtensive applications for
cardiovascular devicescardiovascular devices..
Excellent BiocompatibilityExcellent Biocompatibility
profiles andprofiles and Moduli ofModuli of
elasticity close to that ofelasticity close to that of
bone.bone.

ADVANTAGES
Tissue attachment.Tissue attachment.
Thermal and electrical insulation.Thermal and electrical insulation.
Color control.Color control.
Provides opportunities for attachment of activeProvides opportunities for attachment of active
biomolecules.biomolecules.

LIMITATIONSLIMITATIONS
Poor Mechanical strength.Poor Mechanical strength.
Time dependent changes in the physical characteristics.Time dependent changes in the physical characteristics.
Biodegradation could adversely affect Stability.Biodegradation could adversely affect Stability.
Minimal resistance to scratching or scraping.Minimal resistance to scratching or scraping.

POLYMERS AND COMPOSITESPOLYMERS AND COMPOSITES
These can be designed to match tissue properties and canThese can be designed to match tissue properties and can
be fabricated at relatively low cost.be fabricated at relatively low cost.
These include polytetraflouroethylene (These include polytetraflouroethylene (PTFEPTFE),),
polyethyleneterephthalate (polyethyleneterephthalate (PETPET),),
polymethylmethacrylate (polymethylmethacrylate (PMMAPMMA), polypropylene (), polypropylene (PPPP),),
polysulfone (polysulfone (PSFPSF), silicon rubber (), silicon rubber (SRSR))

PROPERTIESPROPERTIES
Polymers have low strengths and elastic moduliPolymers have low strengths and elastic moduli
and higher elongation to fracture comparedand higher elongation to fracture compared
with other class of biomaterials.with other class of biomaterials.
Relatively resistant to biodegradation comparedRelatively resistant to biodegradation compared
to bone.to bone.

Most uses have been forMost uses have been for internal force distributioninternal force distribution
connectorsconnectors intended to better simulate biomechanicalintended to better simulate biomechanical
conditions for normal tooth functions.conditions for normal tooth functions.
Some are porous where as others are constituted as solidSome are porous where as others are constituted as solid
structural forms.structural forms.

Sensitive to sterilization and handling techniques.Sensitive to sterilization and handling techniques.
Display Electrostatic surface properties.Display Electrostatic surface properties.
Tend to gather dust or other particulate if exposed to semiTend to gather dust or other particulate if exposed to semi
clean oral environments.clean oral environments.
Cleaning the contaminated porous polymers is not possibleCleaning the contaminated porous polymers is not possible
without a laboratory environment.without a laboratory environment.
So the talc on the gloves or contact with towel or gauzeSo the talc on the gloves or contact with towel or gauze
pad or any such contamination must be avoided.pad or any such contamination must be avoided.

TYPES OF SURFACE ROUGHNESS
1) Macrosurface Roughness.
SURFACE TOPOGRAPHY
Screw
Hollow basket
Core vent
2) Microsurface Roughness.
Abraded
TiO2
Al203
Acid Etched
HCl
H2SO4
Coating
TPS
HA
Surface topography relates to the degree of roughness of
the surface and the orientation of surface irregularities.

ADVANTAGES OF INCREASED SURFACE ROUGHNESS
1) Increased surface areas of the implant adjacent to bone.
2) Improved cell attachment to the bone.
3) Increased bone present at implant surface.
4) Increased biomechanical interaction of the implant with
bone.

THREADS
Threads are used to maximize initial contact, initial
stability, increase implant surface area and also favor the
dissipation of interfacial stress.
1) Thread depth
2) Thread thickness
3) Thread Pitch
4) Thread face angle
5) Thread Helix angle

Wennerberg and co-workers
Smooth - to describe abutments,
Minimally rough (0.5 to 1 µm),
Intermediately rough (1 to 2 µm), and
Rough (2 to 3 µm) be used (apart from porous
surfaces for implanted surfaces).
SURFACE TOPOGRAPHY

Literature reports, based on the average
surface roughness surfaces with ≤ 1 µm are
considered smooth, and those with > 1 µm
are described as rough.

Blasting with particles of various diameters is
one of the frequently used method of surface alteration.
In this approach, the implant surface is
bombarded with particles of aluminum oxide (Al2O3)
or titanium oxide (TiO2), and by abrasion, a rough
surface is produced with irregular pits and depressions.
BLASTING

Roughness depends on
particle size, time of blasting,
pressure, and distance from the
source of particles to the implant
surface.
Blasting a smooth Ti surface
with Al2 O3 particles of 25 µm, 75
µm, or 250 µm produces surfaces
with roughness values of 1.16 to
1.20, 1.43, and 1.94 to 2.20,
respectively.
SAND BLASTED IMPLANT
SAND BLASTED AND ACID
ETCHED IMPLANT

Laser Induced Surface Roughening
Eximer laser – “Used to create roughness”
Regularly oriented surface roughness configuration compared
to TPS coating and sandblasting
SEM x 300
SEM x 300SEM x 70

Chemical etching is another process by which
surface roughness can be increased.
The metallic implant is immersed into an acidic
solution, which erodes its surface, creating pits of
specific dimensions and shape.
Concentration of the acidic solution, time, and
temperature are factors determining the result of
chemical attack and microstructure of the surface.
CHEMICAL ETCHING

IRREGULAR SURFACE MORPHOLOGIES
Sandblasted specimen Specimen acid etched for 1 min.
Specimen acid etched for 5 mins. Specimen acid etched for 10 mins.

Recently, a new surface was introduced that was sandblasted
with large grit and acid-etched (SLA, Straumann).
This surface is produced by a large grit (250 to 500 µm)
blasting process, followed by etching with hydrochloric-sulfuric
acid.
The average ra for the acid-etched surface is 1.3 µm, and the
sandblasted and acid-etched surface, ra=2.0 µm.
SANDBLASTED AND ACID ETCHED (SLA)

Sand blasting Acid etch
The objective
Sand blasting – surface roughness
(substractive method)
Acid etching – cleaning
Wennerberg et.al. 1996: superior bone fixation and bone adaptation

SEM 1000X SEM 7000X
Lima YG et al (2000), Orsini Z et al (2000).
Acid etching with NaOH, Aqueous Nitric acid, hydrofluoric acid.
Decrease in contact angle by 100
- better cell attachment.
Increase in osseointegration by removal of aluminium particles
(cleaning).

Porous sintered surfaces are produced when spherical
powders of metallic or ceramic material becomes a coherent mass
with the metallic core of the implant body.
Lack of sharp edges is what distinguishes these from rough
surfaces.
Porous surfaces are characterized by pore size, pore shape,
pore volume, and pore depth, which are affected by the size of
spherical particles and the temperature and pressure conditions of the
sintering chamber.
POROUS

POROUS SURFACE: ADVANTAGES
1. A secure, 3-D interlocking interface with bone.
2. Predictable and minimal crestal bone remodelling.
3. Greater surgical options with shorter implant lengths.
4. Shorter initial healing times
5. Porous coating implants provide the space, volume for
cell migration and attachment, thus support contact
osteogenesis.

SURFACE OF A POROUS TITANIUM
ALLOY IMPLANT
FIBROBLASTS CULTURED FOR 24
HOURS ON THE SURFACE OF A
POROUS TITANIUM ALLOY
IMPLANT.

TITANIUM PLASMA SPRAY

Titanium Plasma Sprayed Coating (TPS)
Steinemann(1988)
Tetsch(1991)-----6-10
times increase surface
area.
Roughness Depth profile of about 15µm

SURFACE OF A TITANIUM PLASMA-SPRAYED IMPLANT. (SEM,
MAGNIFICATION 5,000 X).

HYDROXYAPATITE COATINGS
HA coated implant bioactive
surface structure – more rapid
osseous healing comparison
with smooth surface implant.
↓
Increased initial stability
Can be Indicated
- Type IV bone .
- Fresh extraction sites.
- Newly grafted sites.
SEM 100X
Hydroxyapatite [Hydroxyapatite [CaCa1010((POPO44))6OH6OH]]22 coating was brought to the dentalcoating was brought to the dental
profession byprofession by DeGrootDeGroot

ADVANTAGES OF HA-COATINGS
1. HA coating can lower the corrosion rate of the same substrate
alloys.
2. HA coatings has been credited with enabling to obtain improved
bone to implant attachment compared with machined surface.
3. The bone adjacent to the implant has been reported to be better
organized than with other implant materials and with a higher
degree of mineralization.

CERAMIC AND CERAMIC COATED IMPLANTS
Ceramic materials are used to coat metallic
implants to produce an ionic ceramic surface, which is
thermodynamically stable and hydrophilic, thereby
producing a high strength attachment to bone and
surrounding tissues.
These ceramic can either be plasma sprayed or
coated on to the metal implant to produce bio-active
surface.

Aluminum oxide (Al2O3) is
used as the gold standard for
ceramic implants because of its
inertness with no evidence of ion
release or immune reaction in
vivo.
Zirconia (ZrO2) has also
demonstrated a high
degree of inertness.
THE TÜBINGEN IMPLANT OF ALUMINUM OXIDE HAS
SPECIFIC MICRO-IRREGULARITIES ON THE SURFACE,
CLAIMED TO ALLOW BONE INGROWTH.

OTHER SURFACE MODIFICATIONS
Surface modification methods include controlled
chemical reactions with nitrogen or other elements or surface
ion implantation procedures.

 The reaction of nitrogen with titanium alloys at
elevated temperatures results in titanium nitride
compounds being formed along the surface.
 Electrochemically, the titanium nitrides are similar to
the oxides (TiO2), and no adverse electrochemical
behavior has been noted if the nitride is lost
regionally.
 The titanium substrate reoxidizes when the surface
layer of nitride is removed.

Doped surfaces that contain various types of bone growth factors or
other bone-stimulating agents that may prove advantageous in
compromised bone beds. However, at present clinical documentation
of the efficacy of such surfaces is lacking.
DOPED SURFACES

Physical characteristic:
Physical characteristic refers to the factors such as surface
energy and charge.
Hypothesis : A surface with high energy →high affinity
for adsorption → show stronger osseointegration.
Baier RE (1986) – Glow discharge (plasma cleaning)
results in high surface energy as well as the implant
sterilization, being conductive to tissue integration.

Charge affects the hydrophilic and hydrophobic
characteristic of the surface.
A hydrophilic / easily wettable implant surface :
Increases a initial phase of wound healing.
Increase surface energy would disappear immediately
after implant placement.

Osseointegration in clinical dentistry – Branemark, Zarb,
Albrektsson
Osseointegration and occlusal rehabilitation – Sumiya
Hobo
Contemporary Implant Dentistry – Carl E.Misch
Endosseous implants for Maxillofacial reconstruction –
Block and Kent
Implants in Dentistry –Block and Kent
Dental and Maxillofacial Implantology – John. A.
Hobkrik, Roger Watson

Principles and practice of implant dentistry -Principles and practice of implant dentistry -Charles MCharles M
Weiss, Adam Weiss.Weiss, Adam Weiss.
Atlas of Oral implantology -Atlas of Oral implantology - A Norman CraninA Norman Cranin..
Sciences of dental materials -Sciences of dental materials - AnusaviceAnusavice..
TheThe BRANEMARK systemBRANEMARK system of oral reconstruction - Aof oral reconstruction - A
clinical atlas.clinical atlas.

Endosseous Implant : Scientific and Clinical Aspects –Endosseous Implant : Scientific and Clinical Aspects –
George WatzakGeorge Watzak
Osseointegration in craniofacial reconstruction-Osseointegration in craniofacial reconstruction-
T.T. AlbrektsssonAlbrektssson..
Osseointegration in dentistry : an introduction : PhilipOsseointegration in dentistry : an introduction : Philip
Worthington,Worthington, Brein. RBrein. R.. LangLang,, W.E.W.E. LavelleLavelle..

Dental Clinics Of North America 1986 ; 30 (1) 25-47.Dental Clinics Of North America 1986 ; 30 (1) 25-47.
Dental Clinics Of North America 1992 ; 36, 1-17.Dental Clinics Of North America 1992 ; 36, 1-17.
Implant Materials, Designs.Implant Materials, Designs.
and Surface Topographies :Their effect on Osseointegration.and Surface Topographies :Their effect on Osseointegration.
A Literature ReviewA Literature Review
Nikitas Sykaras et.al.Nikitas Sykaras et.al.
IJOMI 2000 (15) 675-690.IJOMI 2000 (15) 675-690.

Schroeder et alSchroeder et al.,(1981).The reactions of bone,.,(1981).The reactions of bone,
connective tissue, and epithelium to endostealconnective tissue, and epithelium to endosteal
implants with titanium-sprayed surfaces.implants with titanium-sprayed surfaces. Journal ofJournal of
Maxillofacial Surgery 9,15-25.Maxillofacial Surgery 9,15-25.
Zarb & SymingtonZarb & Symington (1983).Osseointegrated dental(1983).Osseointegrated dental
implants: preliminary report on a replication study.implants: preliminary report on a replication study.
Journal of prosthetic dentistry 50,271-279.Journal of prosthetic dentistry 50,271-279.
Albrektsson et alAlbrektsson et al.,(1986).The long-term efficacy of.,(1986).The long-term efficacy of
currently used dental implants: a review andcurrently used dental implants: a review and
proposed criteria for success.proposed criteria for success. International journalInternational journal
of Oral and Maxillofacial Implantsof Oral and Maxillofacial Implants 1,11-25.1,11-25.

Johansson & AlbrektssonJohansson & Albrektsson. (1987) Integration of screw implants. (1987) Integration of screw implants
in the rabbit. A 1- year follow-up of removal of titaniumin the rabbit. A 1- year follow-up of removal of titanium
implants.implants. International journal of 0ral and MaxillofacialInternational journal of 0ral and Maxillofacial
ImplantsImplants 2,69-75.2,69-75.
Albrektsson & SennerbyAlbrektsson & Sennerby.(1991) State of the art in Oral.(1991) State of the art in Oral
implants.implants. Journal of clinical periodontologyJournal of clinical periodontology 18,474-481.18,474-481.
Wennerberg & AlbrektssonWennerberg & Albrektsson.(1993) Design and Surface.(1993) Design and Surface
Characteristics of 13 commercially available oral implantCharacteristics of 13 commercially available oral implant
systems.systems. International Journal of Oral and MaxillofacialInternational Journal of Oral and Maxillofacial
ImplantsImplants 8,622-238,622-23

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