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Biomaterials in Implants
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra2
Contents
• Historical background
• Introduction
• Classification
• Requirements for an ideal implant material
• Bulk properties
• Surface properties
• Biomaterials
• Surface characterization and preparation of biomaterials
• Alternative surface coating techniques
• Sterilization
• Conclusion
• Bibliography
Historical background
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra4
• Tooth loss from disease has always been
a feature of mankind’s existence.
• For centuries people have attempted to
replace missing teeth using implantation.
• Greek, Egyptian civilization used
materials like jade, bone , carved ivory ,
metal and even animal teeth
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra5
• Since then many types of implant
materials were introduced but consistent
failures occured with them
• In 1952 Branemark developed a threaded
implant design made of pure titanium that
showed direct contact with bone.
• Henceforth popularity of implants reached
new heights
Introduction
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra7
• Currently the implant materials available
are diverse
• Success and longevity of implant depends
on fours B’s
– Biomaterial
– Biomechanics
– Biological tissues
– Body serviceability
• Definitive need to have a knowledge of
these biomaterials for their judicious
selection and application in implantology.
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra8
Definition
Biomaterials
• According to GPT-8
• Any substance other than a drug that can
be used for any period of time as part of a
system that treats ,augments or replaces,
any tissue ,organ or function of the body
Classification
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra10
According to composition
1. Metal and Metal alloys
– Titanium
– Titanium alloys (Ti6Al4V)
– Cobalt, Chromium, Molybdenum alloy
(Vitallium)
– Austenitic steel or Surgical steel (Iron ,
Chromium,Nickel alloy )
– Precious metals (Gold ,Platinum,Palladium)
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra11
According to composition
2. Ceramics and carbon
– Aluminium oxide
Alumina
Sapphire
– Zirconium oxide (zirconia)
– Titanium oxide (titania)
– Calcium phosphate ceramics (CPC)
• Hydroxyapatite (HA )
• Tricalcium phosphate( TCP )
– Glass ceramics
– Vitreous carbon (C), Carbon-silicon(C-Si)
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra12
According to composition
3. Polymers
– Poly methyl metha acrylate (PMMA)
– Poly tetra fluoro ethylene (PTFE)
– Poly ethylene terapthylate (Dacron )
– Dimethyl polysiloxane(Silicone rubber)
– Ultrahigh molecular weight polyethylene(UHMW
PE)
– Poly sulphone
4. Composites ( combination of polymer and other
synthetic biomaterials )
– Carbon – PTFE
– Carbon- PMMA
– Alumina- PTFE
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra13
Biological classification – according to
tissue response
1. Biotolerant – Polymers
Fibrous tissue encapsulation at implant
interface
2. Bioinert – Titanium , Ti alloy , Alumina ,
zirconia
Direct bone apposition at the implant interface
3. Bioactive- CPC ,Glass ceramics
Direct chemical bonding of implant with the
surrounding bone
Requirements for an ideal
implant material
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra15
• Any material intended for use as dental
implant must meet 2 basic criteria
– Biocompatibility with living tissue
– Biofunctionality with regard to force transfer
• Implant material should have certain ideal
physical, mechanical, chemical and
biological properties to fulfill these basic
criteria
• Implant properties can be studied under
– Bulk properties
– Surface properties
Bulk properties
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra17
Modulus of elasticity (E)
• Measure of change in dimension (strain) with
respect to stress
• Ideally a biomaterial with elastic modulus
comparable to bone (18GPa )should be selected
• This will ensure more uniform distribution of
stress at implant bone interface as under stress
both of them will deform similarly.
• Hence the relative movement at implant bone
interface is minimized.
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra18
Tensile, Compressive, Shear, Strength
• Forces exerted on implant material
consists of tensile , compressive , shear
components
• An implant material should have high
tensile, compressive, shear strength to
prevent fractures and improve functional
stability.
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra19
Yield strength and Fatigue strength
• Yield strength is magnitude of stress at
which a material shows initial permanent
deformation
• Fatigue strength is stress at which
material fractures under repeated loading
• An implant material should have high yield
strength and fatigue strength to prevent
brittle fracture under cyclic loading
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra20
Ductility
• Refers to relative ability of a material to
deform plastically under a tensile stress
before it fractures
• ADA demands a minimum ductility of 8%
for dental implant
• Required for fabrication of optimal implant
configurations
• Safeguards against brittle fractures of
implant
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra21
Hardness and Toughness
• Hardness – resistance to permanent
surface indentation or penetration
• Increase hardness decreases the
incidence of wear of implant material
• Toughness – amount of energy required
to cause fracture.
• Increased toughness prevents fracture of
the implants.
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra22
Electrical and Thermal conductivity
• Should be minimum to prevent thermal
expansion, contraction, and oral
galvanism.
Surface properties
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra24
Surface tension and surface energy
• Determines
– Wettability of implant by wetting fluid (blood)
– Cleanliness of implant surface
• Surface energy of > 40 dyne / cm
• Surface tension of 40 dyne/cm or more
• Characterstics of very clean surface
• Results in good tissue integration with
load carrying capacity
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra25
Biocompatibility
• Not total inertness
• Ability of a material to perform with an
appropriate biological response in a
specific application
• Mainly a surface phenomenon
• Most important requirement for a
biomaterial
• Depends on
– Corrosion resistance
– Cytotoxicity of corrosion products
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra26
Corrosion resistance
• Corrosion is deterioration of a metal
caused by reaction with its environment
• Following types of corrosion are seen
Stress corrosion
• Failure of a metal by cracking due to
increased stress
Fretting corrosion
• Due to micromotion or rubbing contact
within a corrosive environment
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra27
Crevice corrosion
• Occurs in narrow region eg implant screw –
bone interface
Pitting corrosion
• Occurs in surface pit
• Metal ions dissolve and combine with Cl ions
Galvanic corrosion
• Occurs between two dissimilar metal in contact
within an electrolyte resulting in current flow
between the two.
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra28
Electrochemical corrosion
• In this anodic oxidation and cathodic
reduction takes place resulting in metal
deterioration as well as charge transfer via
electrons.
• All these types of corrosion and charge
transfer can be prevented by presence of
passive oxide layer on metal surface.
• The inertness of this oxide layers imparts
biocompatibility to biomaterials
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra29
Cytotoxicity of corrosion products
• Toxicity of implant materials depends on toxicity
of corrosion products which depends on
– Amount of material dissolved by corrosion per unit
time
– Amount of corroded material removed by metabolic
activity in same unit time
– Amount of corrosion particles deposited in the tissue
• Both increased corrosion resistance and
decreased toxicity of corrosion products
contribute to biocompatibility
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra30
Bone and implant surface interaction
• The implant material should have an
ability to form direct contact or interaction
with bone ( osseointergration)
• This is largely dependent on
biocompatibility and surface composition
of biomaterial ( presence of passivating
oxide layer).
Biomaterials
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra32
Titanium
• Gold standard in implant materials
• Composition of Commercially pure titanium
– Titanium 99.75%
– Iron 0.05%
– Oxygen 0.1%
– Nitrogen 0.03%
– Hydrogen 0.012%
– Carbon 0.05%
• Commercially pure titanium occurs in 4 grades ,
grade I II III IV ,according to oxygen content
(0.18% to 0.40 %) & iron content (0.20 to 0.50 wt
%)
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra33
• Consists of 2 phases α and β phase
• Ti implants are mainly manufactured
through controlled machining ( lathing ,
threading , milling )
• Configuration like cylinders ,screws and
blade forms etc are used
• Casting of titanium alloy is difficult due to
high melting points (1700°C)
• Also titanium readily absorbs nitrogen
hydrogen and oxygen from air during
casting which makes it brittle
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra34
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra35
Properties
Biocompatibility
• Titanium is one of the most biocompatible
material due to its excellent corrosion resistance
• The corrosion resistance is due to formation of
biologically inert oxide layer
Oxide layer
• Titanium spontaneously forms tenacious surface
oxide on exposure to the air or physiologic saline
• Three different oxides are
– TiO Anastase
– TiO2 Rutile
– Ti2 O3 Brookite
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra36
• TiO2 is the most stable and mostly formed
on titanium surface
• This oxide layers is self healing i.e. if
surface is scratched or abraded during
implant placement it repassivates
instantaneously
• Also Ti oxide layer inhibits low level of
charge transfer, lowest among all metals .
This is the main reason for its excellent
biocompatibility
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra37
• Good yield strength , tensile strength ,
fatigue strength .
• Modulus of elasticity (110 GPa) is half of
other alloys and 5 times greater than bone
.This helps in uniform stress distribution
• Good strength ,but less than Ti alloys.
• Ductile enough to be shaped into implant
by machining
• Low density 4.5g/cm3
, light weight
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra38
• Titanium allows bone growth directly
adjacent to oxide surface
• Inspite of excellent corrosion resistance
peri-implant accumulation and also
accumulation in lung, liver, spleen of Ti
ions is seen, however in trace amount it is
not harmful
• Increased level of titanium ions can result
in titanium metallosis.
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra39
Titanium alloys Ti6Al4V
• Consists of
- Titanium
– 6% Aluminium – alpha stabilizer
– 4% Vanadium – beta stabilizer
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra40
Properties
• Excellent corrosion resistance
• Oxide layer formed is resistant to charge
transfer thus contributing to
biocompatibility
• Modulus of elasticity is 5.6 times that of
the bone ,more uniform distribution of
stress
• Strength of titanium alloy is greater than
pure titanium – 6 times that of bone hence
thinner sections can be made
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra41
• Ductility is sufficient
• Exhibits osseointergration
Uses
• Extensively used as implant material due
to excellent biocompatibility ,strength
,osseointegration
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra42
Cobalt , Chromium , Molybdenum alloy
• Composed of same elements as vitallium
• Vitallium introduced in 1937 by Venable
Strock and Beach
• Composition
– 63% Cobalt
– 30% Chromium (CrO provides corrosion
resistance)
– 5% Molybdenum(strength)
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra43
Properties
• High mechanical strength
• Good corrosion resistance
• Low ductility
• Direct apposition of bone to implant though seen
,it is interspersed with fibrous tissue
Uses
• Limited for fabrication of custom designs
for subperiosteal frames due to ease of
castability and low cost.
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra44
Iron , Chromium, Nickel based alloy
• These are Surgical steel alloys or
Austenitic steel
• Have a long history of use as orthopedic
and dental implant devices
Composition
– Iron
– Chromium – 18% - corrosion resistance
– Nickel – 8% - stabilize austenitic steel
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra45
Properties
• High mechanical strength
• High ductility
• Pitting and crevice corrosion.
• Hypersensitivity to nickel has been seen
• Bone implant interface shows fibrous
encapsulation and ongoing foreign body
reactions
• Use is limited
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra46
Precious metals
• Gold , Platinum , Palladium
• They are noble metals unaffected by air ,
moisture , heat and most solvents
• Do not depend on surface oxides for their
inertness
• Low mechanical strength
• Very high ductility
• More cost per unit weight
• Do not demonstrate osseointegration
• Not used
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra47
Ceramics
• Ceramics are inorganic , non metallic materials
manufactured by compacting and sintering at
elevated temperature
• Consist of
• Bioinert ceramics –
– Aluminium oxide
– Titanium oxide
– Zirconium oxide
• Bioactive ceramics –
– Calcium phosphate ceramics – (CPC)
hydroxyapatite (HA)
tricalcium phosphate (TCP)
– Glass ceramics
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra48
Bioinert Ceramics
• These ceramics show direct bone
apposition at implant surface but do not
show chemical bonding to bone
Properties
• Bioinert ceramics are full oxides i.e. bulk
and surface thus excellent bio
compatibility
• Good mechanical strength
• Low ductility which results in brittleneSS
• Color similar to hard tissue
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra49
Uses
• Though initially thought to be suitable for
load bearing dental implants but to due
inferior mechanical properties
• Used as surface coatings over metals
– to enhance their biocompatibility
– to increase the surface area for stronger bone
to implant interface
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra50
Bioactive ceramics
Calcium phosphate ceramics
• These ceramics have evoked greatest
interest in present times
• Mainly consists of
– Hydroxyapatite( HA)
– Tricalcium phosphate( TCP)
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra51
Properties
Biocompatibility
• CPC have biochemical composition similar to
natural bone
• CPC form direct chemical bonding with
surrounding bone due to presence of free
calcium and phosphate compounds as implant
surface
• Excellent biocompatibility
• No local or systemic toxicity
• No alteration to natural mineralization process of
bone
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra52
• Lower mechanical tensile and shear
strength
• Lower fatigue strength
• Brittle, low ductility
• Exists in amorphous or crystalline form
• Exists in dense or porous form
– Macro porous - > 50 µm
– Micro porous - < 50 µm
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra53
• The pores though decrease the strength
they increase the surface area providing
additional region for tissue ingrowth
• Ideal pore size is around 150µm, same
diameter as shown by inter trabecular
spaces in bone
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra54
Solubility of CPC
• CPC show varied degree of resorption or
solubility in physiologic fluids
• The resoption depends on
Crystallinity
– High crystallinity is more resistant to
resorption
Particle size
– Large particles size requires longer time to
resorb
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra55
Porosity
– Greater the porosity, more rapid is the
resorption.
Local environment
– Resorption is more at low pH eg in case of
infection or inflammation
Purity
– presence of impurities accelerate resorption
It has been seen that HA resorb less readily
than TCP
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra56
Uses
• Due to lack of mechanical strength, not
used as load bearing implants
• Used as Bone grafts material for
augmentation of bone
• As bioactive surface coating for various
implant material to increase
– biocompatibility
– strength of tissue integration
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra57
Glass ceramics
• They are bioactive ceramics
• Bioglass or Ceravital
• Silica based glass with additions of
calcium and phosphate produced by
controlled crystallization
Properties
• High mechanical strength
• Less resistant to tensile and bending
stresses
• Extremely brittle
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra58
• They chemically bond to the bone due to
formation of calcium phosphate surface
layer
Uses
• Inferior mechanical properties – not used
as load bearing implant
• Used more often as bone graft material
• When used as coating bond between
coating and metal substrates is weak and
subject to dissolution
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra59
Carbon and carbon silicon compounds
• Vitreous Carbon and Carbon compounds (SiC)were
introduced in 1960 for use in implantology
Properties
• Inert
• Biocompatible
• Modulus of elasticity is close to that of bone
• Bone implant interface shows osseointegration
• Brittle
• Susceptible to fracture under tensile stress
Uses
• Used mainly as surface coatings for implants
materials
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra60
Polymers
• Polymeric implants were first introduced in
1930s
• However they have not found extensive
use in implant due to
• Low mechanical strength
• Lack of osseointegration
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra61
• Used currently to provide shock absorbing
qualities in load bearing metallic implants.
E.g. in IMZ system a polyoxymethylene
intra mobile element (IME) is placed
between prosthesis and implant body
which
– Ensures more uniform stress distribution
– Acts as internal shock absorber
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra62
Composites
• Combination of polymer and other
synthetic biomaterial.
• They have advantages that properties can
be altered to suit clinical application
• Have a promising future .
Surface characterization
and preparation of implants
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra64
• Interaction between host tissue and
implant primarily occurs at implant surface
• Thus characterization of implant surface to
suit clinical needs is of paramount
importance
• Surface characterization can be
accomplished by following techniques
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra65
Passivation –
• Refers to enhancement and stabilization
of oxide layer to prevent corrosion
• Performed by immersion in 40% nitric acid
• Used for Co Cr implant
Acid etching
• In this the surface is treated with nitric or
hydrofluoric acid
• Results in clean surface with roughened
texture for increased tissue adhesion
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra66
Sand blasting
• Sand particles are used to get a
roughened surface texture which
– increases the surface area
– increases the attachment strength at the
bone implant interface
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra67
Surface coatings
• Implant surface may be covered with porous
coatings which increases
• Surface area and roughness
• Attachment strength at bone implant interface
• Biocompatibility
• Several coating techniques exist .
• Plasma sprayed technique is used most
commonly
• Two types
– Plasma sprayed titanium
– Plasma sprayed hydroxyapatite
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra68
Plasma sprayed Titanium
• Described by Schroeder et al ( 1976)
• Titanium particles with mean size of 0.05
to 0.1 are heated in plasma flame
• Plasma flame consists of electric arc
through which argon gas stream passes
• A magnetic coil directs the stream of
molten titanium particles, which is then
sprayed on the titanium surface
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra69
• Thickness of coating 0.04 to 0.05 mm
• Sprayed coating exhibits round pores
that are interconnected ,pore
diameter(150-400µm)
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra70
Advantages
• Increases the surface area by 600%
• Increases attachment of implant to bone
• Increase load bearing capacity
Disadvantages
• Cracking and exfoliation of the coating due
to stresses ,sterilization and insertion.
• Metallic particles found in perimplant
tissue
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra71
Plasma sprayed hydroxyapatite
• Herman 1988
• Crystalline HA powder is heated to a
temperature of 12000 to 16000 °C in a plasma
flame formed by a electric arc through which an
argon gas stream passes .
• HA particle size is approximately 0.04mm
• The particles melt and are sprayed on to the
substrate ,they fall as drops and solidify
• Round interconnected pores are formed
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra72
• Coating bonds to substrate by mechanical
interlocking
• Coating of 0.05 mm is formed
• There is a lot of controversy regarding the ideal
coating thickness
• Studies have shown that:
• Fracture occurred in coatings more than 0.1mm
in thickness
• Whereas bioresorption was unacceptably rapid
with coatings less than 0.03mm in diameter
• Ideal coating thickness of 0.05 mm is
recommended
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra73
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra74
Advantages
• Permits direct chemical bonding of the
bone to implant surface
• Increases surface area
• Stronger bone to implant interface
• Increases corrosion resistance and
biocompatibility
• Decreases healing period of implants
• Bone adjacent to coated implant is better
organized and mineralized ,thus increased
load bearing capacity
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra75
Disadvantages
• Studies have shown that coatings exhibit several
drawbacks:
• Coatings have shown to undergo gradual
resorption over time and subsequent
replacement with bone (creeping substitution)
• Studies have shown that this resorption results
in decreased % of bone implant contact area
over time
• Due to resorption of the coating ,biocompatibility
of exposed and altered core substrate becomes
questionable
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra76
• Bond strength between coating and the
substrate seems to be inadequate to resist
shear stresses
• Due to this weak bond ,coating is
susceptible to removal or fracture during
– sterilization
– insertion in dense bone
• Due to roughened surface, coating often
shows adherence of microorganisms on
their surface
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra77
Indications
• HA coated implants can be used in
• D3 and D4 bone which show poor bone density
and structure as they
– Increase bone contact levels
– Forms stronger bone implant interface
– Increases survival rates
• Fresh extraction sites as they promote
– Faster healing
– Greater initial stability
• Newly grafted sites where implants are to be
placed eg sinus lifts
Alternative surface coating
techniques
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra79
Electrophoretic deposition
• Mineral ions that need to be coated on the
implant surface are dissolved in the
electrolytic bath
• Current flows through electrolyte leading
to formation of surface coating
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra80
Sol gel deposition ( Dip Coating )
• Coating is applied on substrate by dipping
into a solution HA powder and ethanol in
dip coating apparatus and finally sintering
it
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra81
Hot isostatic pressing
• In this the HA powder is mixed with water
and sprayed on the substrate
• It is then hot pressed at 850°C
• The coating produced is dense having
increased shear strength
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra82
Pulsed laser deposition
• Alternative procedure to obtain HA coating
• Nd YAG laser beam is used to spray HA
on the preheated substrate in a vacuum
chamber
• HA coating of greater crystallinity is
obtained that shows decreased resorption
Sterilization
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra84
• Today in most cases manufacturers guarantees
precleaned and presterilized implants ,ready to
be inserted
• In case the implants needs to be resterilized
conventional sterilization techniques are not
satisfactory
• Steam sterilization
– should not be used as it results in contamination of
surfaces with organic substances
• Dry heat sterilization
– Also leaves organic and inorganic surface residues
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra85
Radio frequency glow discharge technique
(RFGDT) or Plasma cleaning
• Most frequently used methods
• In this, material to be cleaned is
bombarded by high energetic ions formed
in gas plasma in a vacuum chamber
• Removes both organic and inorganic
contaminants
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra86
UV light sterilization
– Recently UV light sterilization is also being used
– It cleans the surface and also increase the surface
energy
Gamma radiation
• Method used to sterilize pre packaged dental
implants.
• Radiation dose exceeding 2.5 megavolts is
given
• Components remain protected, clean and sterile
until packaging is opened, within sterile field of
surgical procedure
Conclusion
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra88
• A wide range of biomaterials are currently
in use
• Appropriate selection of biomaterials
directly influences, clinical success and
longevity of implants
• Thus the clinician needs to have adequate
knowledge of the various biomaterials and
their properties for their judicious selection
and application in his clinical practice
Bibliography
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra90
1. Carl E Misch: Contemporary Implant Dentistry
2. Georg Watzek : Endosseous Implant – Scientific And
Clinical Aspects
3. Ralph V Mckinney Jr : Endosseous Dental Implant
4. Babbush : Dental Implants – Principles And Practice
5. Charles M Weiss : Principles And Practice Of Implant
Dentistry
6. Branemark ,Zarb,Albrektsson : Tissue Integration In
Clinical Dentistry
7. Block Kant : Endosseous Implant For Maxillofacial
Reconstruction
8. Philip Worthington, Brien R Long, William E Lavelle :
Osseointegration In Dentistry
9. Phillips : Science Of Dental Materials ,eleventh edition
10. Craig And Powers : Restorative Dental Materials
8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra91
11. Journal of prosthetic dentistry ,49;832-837,1983
12. Journal of prosthetic dentistry,54;410-414,1985
13. International Journal of Prosthodontics,11;391-
401,1998
14. International Journal of Prosthodontics 6;106-117,1993
15. Journal of prosthetic dentistry,49;843 , 1983
16. Journal of clinical periodontology,18;474-481,1991
17. Dental materials,6;106-117,1993
18. Journal of oral maxillofacial surgery,58;1372-
1379,2000
19. Journal of oral maxillofacial surgery,57;1096-1109

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Biomaterials in implants

  • 2. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra2 Contents • Historical background • Introduction • Classification • Requirements for an ideal implant material • Bulk properties • Surface properties • Biomaterials • Surface characterization and preparation of biomaterials • Alternative surface coating techniques • Sterilization • Conclusion • Bibliography
  • 4. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra4 • Tooth loss from disease has always been a feature of mankind’s existence. • For centuries people have attempted to replace missing teeth using implantation. • Greek, Egyptian civilization used materials like jade, bone , carved ivory , metal and even animal teeth
  • 5. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra5 • Since then many types of implant materials were introduced but consistent failures occured with them • In 1952 Branemark developed a threaded implant design made of pure titanium that showed direct contact with bone. • Henceforth popularity of implants reached new heights
  • 7. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra7 • Currently the implant materials available are diverse • Success and longevity of implant depends on fours B’s – Biomaterial – Biomechanics – Biological tissues – Body serviceability • Definitive need to have a knowledge of these biomaterials for their judicious selection and application in implantology.
  • 8. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra8 Definition Biomaterials • According to GPT-8 • Any substance other than a drug that can be used for any period of time as part of a system that treats ,augments or replaces, any tissue ,organ or function of the body
  • 10. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra10 According to composition 1. Metal and Metal alloys – Titanium – Titanium alloys (Ti6Al4V) – Cobalt, Chromium, Molybdenum alloy (Vitallium) – Austenitic steel or Surgical steel (Iron , Chromium,Nickel alloy ) – Precious metals (Gold ,Platinum,Palladium)
  • 11. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra11 According to composition 2. Ceramics and carbon – Aluminium oxide Alumina Sapphire – Zirconium oxide (zirconia) – Titanium oxide (titania) – Calcium phosphate ceramics (CPC) • Hydroxyapatite (HA ) • Tricalcium phosphate( TCP ) – Glass ceramics – Vitreous carbon (C), Carbon-silicon(C-Si)
  • 12. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra12 According to composition 3. Polymers – Poly methyl metha acrylate (PMMA) – Poly tetra fluoro ethylene (PTFE) – Poly ethylene terapthylate (Dacron ) – Dimethyl polysiloxane(Silicone rubber) – Ultrahigh molecular weight polyethylene(UHMW PE) – Poly sulphone 4. Composites ( combination of polymer and other synthetic biomaterials ) – Carbon – PTFE – Carbon- PMMA – Alumina- PTFE
  • 13. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra13 Biological classification – according to tissue response 1. Biotolerant – Polymers Fibrous tissue encapsulation at implant interface 2. Bioinert – Titanium , Ti alloy , Alumina , zirconia Direct bone apposition at the implant interface 3. Bioactive- CPC ,Glass ceramics Direct chemical bonding of implant with the surrounding bone
  • 14. Requirements for an ideal implant material
  • 15. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra15 • Any material intended for use as dental implant must meet 2 basic criteria – Biocompatibility with living tissue – Biofunctionality with regard to force transfer • Implant material should have certain ideal physical, mechanical, chemical and biological properties to fulfill these basic criteria • Implant properties can be studied under – Bulk properties – Surface properties
  • 17. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra17 Modulus of elasticity (E) • Measure of change in dimension (strain) with respect to stress • Ideally a biomaterial with elastic modulus comparable to bone (18GPa )should be selected • This will ensure more uniform distribution of stress at implant bone interface as under stress both of them will deform similarly. • Hence the relative movement at implant bone interface is minimized.
  • 18. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra18 Tensile, Compressive, Shear, Strength • Forces exerted on implant material consists of tensile , compressive , shear components • An implant material should have high tensile, compressive, shear strength to prevent fractures and improve functional stability.
  • 19. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra19 Yield strength and Fatigue strength • Yield strength is magnitude of stress at which a material shows initial permanent deformation • Fatigue strength is stress at which material fractures under repeated loading • An implant material should have high yield strength and fatigue strength to prevent brittle fracture under cyclic loading
  • 20. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra20 Ductility • Refers to relative ability of a material to deform plastically under a tensile stress before it fractures • ADA demands a minimum ductility of 8% for dental implant • Required for fabrication of optimal implant configurations • Safeguards against brittle fractures of implant
  • 21. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra21 Hardness and Toughness • Hardness – resistance to permanent surface indentation or penetration • Increase hardness decreases the incidence of wear of implant material • Toughness – amount of energy required to cause fracture. • Increased toughness prevents fracture of the implants.
  • 22. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra22 Electrical and Thermal conductivity • Should be minimum to prevent thermal expansion, contraction, and oral galvanism.
  • 24. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra24 Surface tension and surface energy • Determines – Wettability of implant by wetting fluid (blood) – Cleanliness of implant surface • Surface energy of > 40 dyne / cm • Surface tension of 40 dyne/cm or more • Characterstics of very clean surface • Results in good tissue integration with load carrying capacity
  • 25. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra25 Biocompatibility • Not total inertness • Ability of a material to perform with an appropriate biological response in a specific application • Mainly a surface phenomenon • Most important requirement for a biomaterial • Depends on – Corrosion resistance – Cytotoxicity of corrosion products
  • 26. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra26 Corrosion resistance • Corrosion is deterioration of a metal caused by reaction with its environment • Following types of corrosion are seen Stress corrosion • Failure of a metal by cracking due to increased stress Fretting corrosion • Due to micromotion or rubbing contact within a corrosive environment
  • 27. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra27 Crevice corrosion • Occurs in narrow region eg implant screw – bone interface Pitting corrosion • Occurs in surface pit • Metal ions dissolve and combine with Cl ions Galvanic corrosion • Occurs between two dissimilar metal in contact within an electrolyte resulting in current flow between the two.
  • 28. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra28 Electrochemical corrosion • In this anodic oxidation and cathodic reduction takes place resulting in metal deterioration as well as charge transfer via electrons. • All these types of corrosion and charge transfer can be prevented by presence of passive oxide layer on metal surface. • The inertness of this oxide layers imparts biocompatibility to biomaterials
  • 29. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra29 Cytotoxicity of corrosion products • Toxicity of implant materials depends on toxicity of corrosion products which depends on – Amount of material dissolved by corrosion per unit time – Amount of corroded material removed by metabolic activity in same unit time – Amount of corrosion particles deposited in the tissue • Both increased corrosion resistance and decreased toxicity of corrosion products contribute to biocompatibility
  • 30. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra30 Bone and implant surface interaction • The implant material should have an ability to form direct contact or interaction with bone ( osseointergration) • This is largely dependent on biocompatibility and surface composition of biomaterial ( presence of passivating oxide layer).
  • 32. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra32 Titanium • Gold standard in implant materials • Composition of Commercially pure titanium – Titanium 99.75% – Iron 0.05% – Oxygen 0.1% – Nitrogen 0.03% – Hydrogen 0.012% – Carbon 0.05% • Commercially pure titanium occurs in 4 grades , grade I II III IV ,according to oxygen content (0.18% to 0.40 %) & iron content (0.20 to 0.50 wt %)
  • 33. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra33 • Consists of 2 phases α and β phase • Ti implants are mainly manufactured through controlled machining ( lathing , threading , milling ) • Configuration like cylinders ,screws and blade forms etc are used • Casting of titanium alloy is difficult due to high melting points (1700°C) • Also titanium readily absorbs nitrogen hydrogen and oxygen from air during casting which makes it brittle
  • 34. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra34
  • 35. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra35 Properties Biocompatibility • Titanium is one of the most biocompatible material due to its excellent corrosion resistance • The corrosion resistance is due to formation of biologically inert oxide layer Oxide layer • Titanium spontaneously forms tenacious surface oxide on exposure to the air or physiologic saline • Three different oxides are – TiO Anastase – TiO2 Rutile – Ti2 O3 Brookite
  • 36. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra36 • TiO2 is the most stable and mostly formed on titanium surface • This oxide layers is self healing i.e. if surface is scratched or abraded during implant placement it repassivates instantaneously • Also Ti oxide layer inhibits low level of charge transfer, lowest among all metals . This is the main reason for its excellent biocompatibility
  • 37. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra37 • Good yield strength , tensile strength , fatigue strength . • Modulus of elasticity (110 GPa) is half of other alloys and 5 times greater than bone .This helps in uniform stress distribution • Good strength ,but less than Ti alloys. • Ductile enough to be shaped into implant by machining • Low density 4.5g/cm3 , light weight
  • 38. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra38 • Titanium allows bone growth directly adjacent to oxide surface • Inspite of excellent corrosion resistance peri-implant accumulation and also accumulation in lung, liver, spleen of Ti ions is seen, however in trace amount it is not harmful • Increased level of titanium ions can result in titanium metallosis.
  • 39. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra39 Titanium alloys Ti6Al4V • Consists of - Titanium – 6% Aluminium – alpha stabilizer – 4% Vanadium – beta stabilizer
  • 40. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra40 Properties • Excellent corrosion resistance • Oxide layer formed is resistant to charge transfer thus contributing to biocompatibility • Modulus of elasticity is 5.6 times that of the bone ,more uniform distribution of stress • Strength of titanium alloy is greater than pure titanium – 6 times that of bone hence thinner sections can be made
  • 41. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra41 • Ductility is sufficient • Exhibits osseointergration Uses • Extensively used as implant material due to excellent biocompatibility ,strength ,osseointegration
  • 42. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra42 Cobalt , Chromium , Molybdenum alloy • Composed of same elements as vitallium • Vitallium introduced in 1937 by Venable Strock and Beach • Composition – 63% Cobalt – 30% Chromium (CrO provides corrosion resistance) – 5% Molybdenum(strength)
  • 43. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra43 Properties • High mechanical strength • Good corrosion resistance • Low ductility • Direct apposition of bone to implant though seen ,it is interspersed with fibrous tissue Uses • Limited for fabrication of custom designs for subperiosteal frames due to ease of castability and low cost.
  • 44. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra44 Iron , Chromium, Nickel based alloy • These are Surgical steel alloys or Austenitic steel • Have a long history of use as orthopedic and dental implant devices Composition – Iron – Chromium – 18% - corrosion resistance – Nickel – 8% - stabilize austenitic steel
  • 45. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra45 Properties • High mechanical strength • High ductility • Pitting and crevice corrosion. • Hypersensitivity to nickel has been seen • Bone implant interface shows fibrous encapsulation and ongoing foreign body reactions • Use is limited
  • 46. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra46 Precious metals • Gold , Platinum , Palladium • They are noble metals unaffected by air , moisture , heat and most solvents • Do not depend on surface oxides for their inertness • Low mechanical strength • Very high ductility • More cost per unit weight • Do not demonstrate osseointegration • Not used
  • 47. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra47 Ceramics • Ceramics are inorganic , non metallic materials manufactured by compacting and sintering at elevated temperature • Consist of • Bioinert ceramics – – Aluminium oxide – Titanium oxide – Zirconium oxide • Bioactive ceramics – – Calcium phosphate ceramics – (CPC) hydroxyapatite (HA) tricalcium phosphate (TCP) – Glass ceramics
  • 48. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra48 Bioinert Ceramics • These ceramics show direct bone apposition at implant surface but do not show chemical bonding to bone Properties • Bioinert ceramics are full oxides i.e. bulk and surface thus excellent bio compatibility • Good mechanical strength • Low ductility which results in brittleneSS • Color similar to hard tissue
  • 49. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra49 Uses • Though initially thought to be suitable for load bearing dental implants but to due inferior mechanical properties • Used as surface coatings over metals – to enhance their biocompatibility – to increase the surface area for stronger bone to implant interface
  • 50. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra50 Bioactive ceramics Calcium phosphate ceramics • These ceramics have evoked greatest interest in present times • Mainly consists of – Hydroxyapatite( HA) – Tricalcium phosphate( TCP)
  • 51. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra51 Properties Biocompatibility • CPC have biochemical composition similar to natural bone • CPC form direct chemical bonding with surrounding bone due to presence of free calcium and phosphate compounds as implant surface • Excellent biocompatibility • No local or systemic toxicity • No alteration to natural mineralization process of bone
  • 52. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra52 • Lower mechanical tensile and shear strength • Lower fatigue strength • Brittle, low ductility • Exists in amorphous or crystalline form • Exists in dense or porous form – Macro porous - > 50 µm – Micro porous - < 50 µm
  • 53. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra53 • The pores though decrease the strength they increase the surface area providing additional region for tissue ingrowth • Ideal pore size is around 150µm, same diameter as shown by inter trabecular spaces in bone
  • 54. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra54 Solubility of CPC • CPC show varied degree of resorption or solubility in physiologic fluids • The resoption depends on Crystallinity – High crystallinity is more resistant to resorption Particle size – Large particles size requires longer time to resorb
  • 55. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra55 Porosity – Greater the porosity, more rapid is the resorption. Local environment – Resorption is more at low pH eg in case of infection or inflammation Purity – presence of impurities accelerate resorption It has been seen that HA resorb less readily than TCP
  • 56. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra56 Uses • Due to lack of mechanical strength, not used as load bearing implants • Used as Bone grafts material for augmentation of bone • As bioactive surface coating for various implant material to increase – biocompatibility – strength of tissue integration
  • 57. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra57 Glass ceramics • They are bioactive ceramics • Bioglass or Ceravital • Silica based glass with additions of calcium and phosphate produced by controlled crystallization Properties • High mechanical strength • Less resistant to tensile and bending stresses • Extremely brittle
  • 58. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra58 • They chemically bond to the bone due to formation of calcium phosphate surface layer Uses • Inferior mechanical properties – not used as load bearing implant • Used more often as bone graft material • When used as coating bond between coating and metal substrates is weak and subject to dissolution
  • 59. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra59 Carbon and carbon silicon compounds • Vitreous Carbon and Carbon compounds (SiC)were introduced in 1960 for use in implantology Properties • Inert • Biocompatible • Modulus of elasticity is close to that of bone • Bone implant interface shows osseointegration • Brittle • Susceptible to fracture under tensile stress Uses • Used mainly as surface coatings for implants materials
  • 60. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra60 Polymers • Polymeric implants were first introduced in 1930s • However they have not found extensive use in implant due to • Low mechanical strength • Lack of osseointegration
  • 61. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra61 • Used currently to provide shock absorbing qualities in load bearing metallic implants. E.g. in IMZ system a polyoxymethylene intra mobile element (IME) is placed between prosthesis and implant body which – Ensures more uniform stress distribution – Acts as internal shock absorber
  • 62. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra62 Composites • Combination of polymer and other synthetic biomaterial. • They have advantages that properties can be altered to suit clinical application • Have a promising future .
  • 64. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra64 • Interaction between host tissue and implant primarily occurs at implant surface • Thus characterization of implant surface to suit clinical needs is of paramount importance • Surface characterization can be accomplished by following techniques
  • 65. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra65 Passivation – • Refers to enhancement and stabilization of oxide layer to prevent corrosion • Performed by immersion in 40% nitric acid • Used for Co Cr implant Acid etching • In this the surface is treated with nitric or hydrofluoric acid • Results in clean surface with roughened texture for increased tissue adhesion
  • 66. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra66 Sand blasting • Sand particles are used to get a roughened surface texture which – increases the surface area – increases the attachment strength at the bone implant interface
  • 67. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra67 Surface coatings • Implant surface may be covered with porous coatings which increases • Surface area and roughness • Attachment strength at bone implant interface • Biocompatibility • Several coating techniques exist . • Plasma sprayed technique is used most commonly • Two types – Plasma sprayed titanium – Plasma sprayed hydroxyapatite
  • 68. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra68 Plasma sprayed Titanium • Described by Schroeder et al ( 1976) • Titanium particles with mean size of 0.05 to 0.1 are heated in plasma flame • Plasma flame consists of electric arc through which argon gas stream passes • A magnetic coil directs the stream of molten titanium particles, which is then sprayed on the titanium surface
  • 69. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra69 • Thickness of coating 0.04 to 0.05 mm • Sprayed coating exhibits round pores that are interconnected ,pore diameter(150-400µm)
  • 70. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra70 Advantages • Increases the surface area by 600% • Increases attachment of implant to bone • Increase load bearing capacity Disadvantages • Cracking and exfoliation of the coating due to stresses ,sterilization and insertion. • Metallic particles found in perimplant tissue
  • 71. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra71 Plasma sprayed hydroxyapatite • Herman 1988 • Crystalline HA powder is heated to a temperature of 12000 to 16000 °C in a plasma flame formed by a electric arc through which an argon gas stream passes . • HA particle size is approximately 0.04mm • The particles melt and are sprayed on to the substrate ,they fall as drops and solidify • Round interconnected pores are formed
  • 72. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra72 • Coating bonds to substrate by mechanical interlocking • Coating of 0.05 mm is formed • There is a lot of controversy regarding the ideal coating thickness • Studies have shown that: • Fracture occurred in coatings more than 0.1mm in thickness • Whereas bioresorption was unacceptably rapid with coatings less than 0.03mm in diameter • Ideal coating thickness of 0.05 mm is recommended
  • 73. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra73
  • 74. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra74 Advantages • Permits direct chemical bonding of the bone to implant surface • Increases surface area • Stronger bone to implant interface • Increases corrosion resistance and biocompatibility • Decreases healing period of implants • Bone adjacent to coated implant is better organized and mineralized ,thus increased load bearing capacity
  • 75. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra75 Disadvantages • Studies have shown that coatings exhibit several drawbacks: • Coatings have shown to undergo gradual resorption over time and subsequent replacement with bone (creeping substitution) • Studies have shown that this resorption results in decreased % of bone implant contact area over time • Due to resorption of the coating ,biocompatibility of exposed and altered core substrate becomes questionable
  • 76. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra76 • Bond strength between coating and the substrate seems to be inadequate to resist shear stresses • Due to this weak bond ,coating is susceptible to removal or fracture during – sterilization – insertion in dense bone • Due to roughened surface, coating often shows adherence of microorganisms on their surface
  • 77. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra77 Indications • HA coated implants can be used in • D3 and D4 bone which show poor bone density and structure as they – Increase bone contact levels – Forms stronger bone implant interface – Increases survival rates • Fresh extraction sites as they promote – Faster healing – Greater initial stability • Newly grafted sites where implants are to be placed eg sinus lifts
  • 79. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra79 Electrophoretic deposition • Mineral ions that need to be coated on the implant surface are dissolved in the electrolytic bath • Current flows through electrolyte leading to formation of surface coating
  • 80. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra80 Sol gel deposition ( Dip Coating ) • Coating is applied on substrate by dipping into a solution HA powder and ethanol in dip coating apparatus and finally sintering it
  • 81. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra81 Hot isostatic pressing • In this the HA powder is mixed with water and sprayed on the substrate • It is then hot pressed at 850°C • The coating produced is dense having increased shear strength
  • 82. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra82 Pulsed laser deposition • Alternative procedure to obtain HA coating • Nd YAG laser beam is used to spray HA on the preheated substrate in a vacuum chamber • HA coating of greater crystallinity is obtained that shows decreased resorption
  • 84. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra84 • Today in most cases manufacturers guarantees precleaned and presterilized implants ,ready to be inserted • In case the implants needs to be resterilized conventional sterilization techniques are not satisfactory • Steam sterilization – should not be used as it results in contamination of surfaces with organic substances • Dry heat sterilization – Also leaves organic and inorganic surface residues
  • 85. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra85 Radio frequency glow discharge technique (RFGDT) or Plasma cleaning • Most frequently used methods • In this, material to be cleaned is bombarded by high energetic ions formed in gas plasma in a vacuum chamber • Removes both organic and inorganic contaminants
  • 86. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra86 UV light sterilization – Recently UV light sterilization is also being used – It cleans the surface and also increase the surface energy Gamma radiation • Method used to sterilize pre packaged dental implants. • Radiation dose exceeding 2.5 megavolts is given • Components remain protected, clean and sterile until packaging is opened, within sterile field of surgical procedure
  • 88. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra88 • A wide range of biomaterials are currently in use • Appropriate selection of biomaterials directly influences, clinical success and longevity of implants • Thus the clinician needs to have adequate knowledge of the various biomaterials and their properties for their judicious selection and application in his clinical practice
  • 90. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra90 1. Carl E Misch: Contemporary Implant Dentistry 2. Georg Watzek : Endosseous Implant – Scientific And Clinical Aspects 3. Ralph V Mckinney Jr : Endosseous Dental Implant 4. Babbush : Dental Implants – Principles And Practice 5. Charles M Weiss : Principles And Practice Of Implant Dentistry 6. Branemark ,Zarb,Albrektsson : Tissue Integration In Clinical Dentistry 7. Block Kant : Endosseous Implant For Maxillofacial Reconstruction 8. Philip Worthington, Brien R Long, William E Lavelle : Osseointegration In Dentistry 9. Phillips : Science Of Dental Materials ,eleventh edition 10. Craig And Powers : Restorative Dental Materials
  • 91. 8th August 2006 Biomaterials in Implants - Dr Shilpi Gilra91 11. Journal of prosthetic dentistry ,49;832-837,1983 12. Journal of prosthetic dentistry,54;410-414,1985 13. International Journal of Prosthodontics,11;391- 401,1998 14. International Journal of Prosthodontics 6;106-117,1993 15. Journal of prosthetic dentistry,49;843 , 1983 16. Journal of clinical periodontology,18;474-481,1991 17. Dental materials,6;106-117,1993 18. Journal of oral maxillofacial surgery,58;1372- 1379,2000 19. Journal of oral maxillofacial surgery,57;1096-1109