MATERIALS USED FOR DENTAL IMPLANT / dental implant courses by Indian dental academy

MATERIALS USEDMATERIALS USED
FOR DENTALFOR DENTAL
IMPLANTIMPLANT
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

Contents:
 Introduction
 History
 Physical And Mechanical Properties
 Corrosion And Biodegradation
 Classification of dental implant materials
 Metalsand alloysused :
 Ti-6Al-4V
 Cobalt-Chromium-Molybdenum based alloys
 Iron-Chromium-Nickel-based alloys

OTHER MATERIALS USED
 Ceramics and carbon
 Polymers and composites
 Surface characteristics
 Tissue interactions
 Surface energy
 Passivation and Chemical cleaning
 Sterilization
 Summary

INTRODUCTIOINTRODUCTIO
NN

The physical,mechanical,chemical and
electrical properties of the basic material
components must always be fully evaluated for any
biomaterial application,as these properties provide
key inputs into the biomechanical and biologic
analysis of function.
Therefore the desire to positively influence
tissue responses and to minimize biodegradation
often places restrictions on which materials can be
safely used within the oral and tissue environment

HistoryHistory
 Ancient Implants:
Implanted animal & Carved ivory teeth cited
in ancient Egyptian writings are the oldest
examples of primitive implantology.
Attempts to replace lost teeth with endosteal
implants have been traced to early Egyptian &
South American civilizations.
A skull from Pre-Columbian era in Peabody
museum of Harvard Univ in which an artificial
tooth carved from dark stone replaced a lower left
lateral incisor.

 The earliest dental implants were of stone & ivory in
16th
century.
 Root replacement was by allogenic tooth
transplantation which became popular in 17th
century.
 Metal implant devices of gold, lead, irridium,
tantalum, stainless steel were developed in 20th
century.
 Co-Cr, molybdenum sub-periosteal & Ti blade
implants were introduced in 1940’s.
 Non metal bio-materials such as Vitreous & pyrolytic
carbon, aluminum oxide, HA were introduced in
1970’s.

PHYSICAL AND MECHANICAL
PROPERTIES
The fatigue limit of metallic implant materials
reaches 50% of their ultimate tensile
strength.However this relationship is only
applicable to metallic and polymeric systems.
Ceramic materials are weak under shear
forces due to the combination of lack of fracture
toughness and no ductility which can lead to brittle
fracture.According to ASTM metals should have
minimum ductility of 8% to minimize brittle fracture.www.indiandentalacademy.com

CORROSION & BIODEGRADATION
Corrosion is a special concern for metallic
materials in dental implantalogy because implants
protrude into the oral cavity where electrolyte and
oxygen compositions differ from those of tissue
fluids.In addition the pH can change significantly in
areas below plaque and within the oral cavity.
Plenk and Zitter (1996) stated that galvanic
corrosion can be greater for dental implants than
for orthopedic implants
Galvanic process depends on the passivity of
oxide layers which is only a few nanometers thick
and is usually made up of oxides or hydroxides of
the metallic elements that have greatest affinity for
oxygen. www.indiandentalacademy.com

 According to Williams three types of
corrosion are most relevant to dental implants:
Stress corrosion cracking
Galvanic corrosion cracking
Fretting corrosion cracking
Even ceramic oxide materials are not fully
degradation resistant.The corrosion resistance of
synthetic polymers on the other hand depends not
only on their composition but also on their degree
of polymerization.www.indiandentalacademy.com

CLASSIFICATION
Biodynamic
Activity
Biotolerant Gold
Co-Cr alloys
Stainless Steel
Zirconium
Polyethylene
Polyamide
Polymethylmeth
acrylate
Polytetrafluoroe
thylene
Bioinert Commercially
Pure Ti
Ti alloy(Ti-6AI-
4V)
Al2O3,Zr2O3
Bioactive HA,Ca3PO4,
FA,Brushite,
Bioglass
Metals Ceramics Polymers
Chemical Composition

BIOTOLERANT:Biotolerant materials are those
that are not necessarily rejected when implanted
into the living tissue,but are surrounded by a
fibrous layer in the form of capsule.
BIOINERT:These allow close apposition of bone
on their surface,leading to contact osteogenesis.
BIOACTIVE:These materials also allow the
formation of new bone onto their surface,but ion
exchange with host tissue leads to the formation of
a chemical bond along the interface(bonding
osteogenesis).

TITANIUM AND Ti-6Al-4V
This reactive group of metals and alloys form
tenacious oxides in air or oxygenated solutions.
This passivated surface minimizes the bio-
corrosion phenomenon.
In situations where the implant would be
placed within a closely fitting receptor site in
bone,areas scratched or abraded during placement
would re-passivate in vivo.

Titanium shows relatively low modulus of
elasticity and tensile strength when compared with
most other alloys.Yet its modulus of elasticity is 5
times greater than that of the compact bone,and
this property places emphasis on the importance of
design in the proper distribution of mechanical
stress transfer.
The strength values for wrought soft and
ductile metallurgic condition are approximately 1.5
times greater than the strength of compact bone.
In most designs where the bulk dimensions
and shapes are simple strength of this magnitude is
adequate.
Sharp corners or thin sections must be
avoided for regions loaded under tension or shear
conditions.

Classification of commercially pure
titanium:
Grade I –0.18% Oxygen
Grade IV-0.4% Oxygen
Traces of other elements such as
nitrogen,carbon,hydrogen,iron and vanadium
added for stability or improvement of mechanical
and physicochemical properties.
Pure titanium is mechanically much more
ductile than Ti alloys.
The need for adjustment or bending to
provide parallel abutments for prosthetic treatment
has caused manufacturers to optimize
microstructure and residual strain conditions.www.indiandentalacademy.com

Classification of commercially pure
titanium:
Grade I –0.18% Oxygen
Grade IV-0.4% Oxygen
Traces of other elements such as
nitrogen,carbon,hydrogen,iron and vanadium
added for stability or improvement of mechanical
and physicochemical properties.
Commercially pure Ti is mechanically much

The need for adjustment or bending to
provide parallel abutments for prosthetic
treatments has caused manufacturers to optimize
microstructure and residual strain conditions.
However if an implant abutment is bent at the
time of implantation, the metal is strained locally at
the neck region and the local strain is both
cumulative and dependent on the total amount of
deformation introduced during the procedure.

COBALT CHROMIUM
MOLYBDENUM BASED ALLOY
COMPOSITION:
Cobalt
Chromium
Molybdenum
Carbon
Nickel
Manganese

IRON CHROMIUM NICKEL BASED
ALLOYS
This alloy as with Ti systems is used most often in
wrought and heat treated metallurgic conditions,which
results in a high strength and high ductility alloy.
The ramus blade,ramus frame,stabilizer fins and
some mucosal insert systems have been made from the
iron based alloy.
Because this alloy contains nickel as major
elements,use in patients allergic or hypersensitive to
nickel should be avoided.
If a stainless steel implant is modified before
surgery, procedures for repassivation to obtain oxidized
surface is recommended.

Iron based alloys have galvanic potentials and
corrosion characteristics that could result in
concerns about galvanic coupling and bio-corrosion
if interconnected with Ti,Co,Zr or C implant
biomaterials.

OTHER METALS AND ALLOYS
Tantalum,Platinum,Iridium,Gold,Palladium
and alloys of these metals.More recently devices
made from Zirconium,Hafnium and Tungsten have
been evaluated.
Gold,Platinum and Palladium are metals of
relatively low strength which places limits on
implant design. But still Gold is used because of
nobility and availability.

CERAMICS AND CARBON
Ceramics are inorganic non metallic, non
polymeric materials manufactured by compacting
and sintering at elevated temperatures.
Because of their inertness to
biodegradation,high strength, physical
characteristics such as color and minimal thermal
and electrical conductivity,and a wide range
material specific elastic properties they are in use.
However the low ductility or inherent
brittleness has resulted in limitations.Ceramics
have been used in bulk forms and more recently as
coatings on metals and alloys.www.indiandentalacademy.com

ALUMINA,TITANIUM & ZIRCONIUM
OXIDES
High ceramics from aluminum,titanium and
zirconium oxides have been used for root
form,endosteal plate form and pin type dental
implants.
The compressive,tensile and bending
strength exceed the strength of the compact bone
by 3-5 times.These properties combined with high
moduli of elasticity and especially with fatigue and
fracture strength have resulted in specialized
design requirements.
The Al, Ti and Zr oxide ceramics have a clear
white,cream or light gray color which is beneficial
for applications in anterior root form devices.www.indiandentalacademy.com

In early studies of dental and orthopedic
devices in laboratory animals and humans ceramics
have exhibited direct interphases with bone similar
to an Osseo integrated condition with Ti.
One series of root form and plate form
devices used during the 1970s resulted in intra oral
fractures after several years of function.The
fractures were initiated by fatigue cycling where
biomechanical stresses were along regions of
localized bending and tensile loading.

BIOACTIVE AND BIODEGRADABLE
CERAMICS BASED ON CALCIUM
PHOSPHATE
The CaPO4 ceramics used in dental
reconstructive surgery include a wide range of
implant types and thereby a wide range of clinical
implications .
The laboratory and clinical results for CaPO4
particulates were most promising and led to
expansions for implant application.
In general these classes of bio-ceramics have
lower strength,hardness and modulus of elasticity
than the more chemically inert forms previously
discussed .
Calcium aluminates,sodium lithium inert
glasses with CaPO4 and glass ceramics provide a
wide range of properties and have found extendedwww.indiandentalacademy.com

BIOACTIVE CERAMIC
PROPERTIES
 Physical properties are specific to surface area or
form of the product,porosity and
crystallinity.Chemical properties are related to CaPO4
ratio,composition and elemental impurities such as
carbonate ionic substitution in atomic structure forms
can exist with exposure to water.this has caused some
confusion in the literature,in that some CaPO4
ceramics have been steam autoclaved for sterilization
purposes before surgical implantation.
Steam or water autoclaving can significantly change
the basic structure and properties of CaPO4 ceramics
& thereby provide an unknown biomaterial condition
at the time of implantation.

Forms,Microstructure & Mechanical
Properties.
 Hydroxyapatite provided in a non-porous form as
a spherical or angular shaped particles, is an
example of crystalline, high purity HA
biomaterial.
 These particles can have relatively high
compressive strength up to 500mPa,with tensile
strength in the range of 50-70mPa.
 Ceramics are brittle materials and exhibit high
compressive strength compared with tensile
strength.However,less resistance to tensile and
shear stresses limit their application as dental
implants because of mechanical constraints of
implant form & volume.www.indiandentalacademy.com

 Non-resorbable, bio inert ceramics exhibiting
satisfactory load bearing capacity are limited to
dense mono and poly crystalline Al, Zr & Ti oxide
ceramics.
 These same mechanical characteristics exist for
the solid portions of several porous HA
particulates and blocks.
 The macroporous or microporous particulates
have an increased surface area/unit vol. This
provides more surface area for solution and
cell ,mediated resorption under static conditions
and a significant reduction in compressive &
tensile strength.

 The porous materials also provide additional regions
for tissue in growth & integration & thereby
minimization of interfacial motion and dynamic
interfacial breakdown.
 Bulk form implant designs made from CaPO4
ceramics,which were shown to be contraindicated
for some implant designs because of poor
mechanical performance, have found a wide range of
indications as coatings of stronger implant materials.
 These coatings for the most part are applied by
Plasma spraying, have average thickness between
50 & 70micrometers are mixtures of crystalline and
amorphous phases and have a variable micro
structure compared with the solid portions of the
particulate forms of HA and Ca3PO4www.indiandentalacademy.com

Density, Conductivity & Solubility
 Bioactive ceramics are especially interesting for
implant dentistry because the inorganic portion of
the recipient bone is likely to grow next to a more a
chemically similar material.
 Under the bioactive categorization:CaPO4 materials
such as TCP, HA, CaCO3 ,Ca2SO4 & ceramics are
included.
 Their limitations have been associated wit material
forms that have lower strength.
 Dissolution characteristics of bioactive ceramics
have been determined for both particulates and
coatings.
 In general, solubility is greater for TCP than for
HA.The solubility profiles depends on the
environment.

 The larger the particle size, the longer the
material will remain at the site.
 The porosity of the product also impacts the
resorption rate.
 The porous or the holes are regions where blood
components and organic materials can reside
when placed within the bone and represent the
regions where living material existed before the
exploration and processing of implant material.
 The greater the porosity, the more rapid the
resorption of the graft material.www.indiandentalacademy.com

 The hard & soft tissues of the body are more able
to degrade the components & resorb the
amorphous forms of grafting materials.
 Thus, crystalline forms of HA are found to be
very stable over a long term under normal
conditions, whereas, amorphous structures are
more likely to exhibit resorption and
susceptibility to enzymes or cell mediated
breakdown.
 The pH in the region in which the bone
substitutes are placed also affects the rate of
resorption. As the pH decreases the
components of living bone primarily the CaPO4
resorb by solution mediated activity.
 Since CaPO4 is a non conductor of heat, it can
be used as a coating for implants when mixture
of conductive materials are included in the
overall prosthetic reconstruction.www.indiandentalacademy.com

Carbon & Carbon Silicon Compounds
 Carbon compounds are often classified under
ceramics because of their chemical inertness &
absence of ductility,however they are
conductors of heat & electricity.
 Ceramic & carbonatic substances continue to be
used as coatings on metallic & ceramic
materials.
 Advantages:
 Tissue attachment
 Opportunities for the attachment of active bio-
molecules/synthetic compounds.
Disadvantage:
Lack of mechanical strength propertieswww.indiandentalacademy.com

Polymers & Composites
 Advantages of Fiber reinforced polymers:
 Can be designed to match tissue properties
 Can be anisotropic wrt mechanical
characteristics
 Can be coated for attachment to tissues &
 Can be fabricated at relatively low costwww.indiandentalacademy.com

Structural Biomaterial Polymers
 In general, polymers have low strength & elastic
moduli and higher elongations to fracture
compared with other classes of biomaterials
 They are thermal & electrical insulators.
 They are relatively resistant to bio degradation
 Polymers have been fabricated in porous and
solid forms for tissue attachment, replacement,
augmentation & as coatings for force transfer to
soft & hard tissue region

 Cold flow characteristics,creep & fatigue
strengths are relatively low for some classes of
polymers.
ex: SR
PMMA
 In contrast some are extremely tough and
fatigue cycle resistant.
ex:PP
UHMW-PE
PTFE
 The indications for PTFE have grown
exponentially in the last decade because of the
development of membranes for guided tissue
regeneration technique.www.indiandentalacademy.com

 Most of the inert polymers have been combined
with particulate or fibers of carbon, Aluminum
oxide, HA & glass ceramics.
 In some cases, bio degradable polymers such as
Poly Vinyl Alcohol,Poly Lactides or
Glycolides,Cyanoacralates or other Hydra table
forms have been combined with bio degradable
CaPO4 particulate or fibers.
 These are intended as structural scaffolds,
plates, screws or other such applications.
COMPOSITES

Surface characteristics
 The biomaterial characteristics can be
separated into 2 categories associated either
with
 Surface
 Bulk properties
 In general, the biomaterial surface chemistry,
topography & type of tissue integration can be
correlated with shorter & longer term in vivo
host responses.
 The host environment has been shown to directly
influence the biomaterial to tissue inter facial
zone specific to the local biochemical &
biomechanical circumstances of healing and
long term clinical aspects of load bearing
function. www.indiandentalacademy.com

Surface Characterization & Tissue
Interaction-Metal & Alloy Surfaces
 There is a formation of thin oxide due to a
reaction with oxygen or other mechanisms such
as oxygen or metal ions diffusion from and to the
metallic surface, especially for Ti.
 This thin layer of amorphous oxide will rapidly
reform if removed mechanically.
 Surface properties are due to this oxide layer
and differ fundamentally from metallic substrate.
 Therefore the oxidation parameters such as
temperature, type & concentration of oxidizing
elements & eventual contaminants- all influence
the physical & chemical properties of the final
implant product.

 The surgical implant is primarily amorphous in
atomic structure if formed in normal
temperature, air or tissue fluid environments and
is very adherent & thin in thickness (<20nm)
 In contrast, if unalloyed Ti substrates are
processed at elevated temperatures, the oxide
forms a crystalline atomic structure & can be 10-
100 time thicker.
 Low temperatures thermal oxides are relatively
homogenous & dense.
 The role of alloying elements in Ti alloys & how
these elemental compositions may influence
oxide properties & host tissue compatibility—is
dependent on the amount of ions available to the
tissues & relative rates of ion transfers

Tissue Interactions
 Oxide modifications during in vivo exposure has been
shown to result in increased Ti oxide layer thickness
of up to 200nm.
 The highest growth area corresponded to a bone
marrow site while the lowest growth was associated
with Ti, in contact with cortical regions of bone.
 Increased levels of Ca & Phosphorous were found in
oxide surface layers and seemed to indicate an
active exchange of ions at the interface.
 The surface bio interaction process maybe slow or
activated by local reactions and may cause ion
release and oxide alteration of the substrate
 Especially high rates of ion release were observed in
EDTA & sodium citrate solutions & varied as a
function of the corroding media.

Integration with Titanium
 Although Ti is known to exhibit better corrosion
resistance, independent of the surface preparation,in
vivo & in vitro, studies have shown that Ti may interact
with recipient living tissues over several years.
 Bundy (1993) exposed implant alloys simultaneously to
tensile stress & corrosive environments. In vivo,
stainless & Ti alloy demonstrated cracks when loaded
to yield stress & re-implanted under lab conditions for 8
weeks. Crack like features were also seen in stainless
steel & TI alloys loaded to or beyond the yield stress &
subsequently electrochemically polarized for 38 weeks
in the in-vitro part of the study
None of the samples actually failed by
completely cracking but the author presumed that it
would have occurred with a longer exposure time as
previously suggested.www.indiandentalacademy.com

 Lemons (1977) studied single staged solid
implants modified by bending or cutting &
showed that damage could increase corrosion.
 Cohen & Burdairon (1978) showed that
odontogenic fluoride gels which create an acidic
environment can lead to the degradation of the
Ti oxide layer & possibly inhibit the Osseo-
integration process.www.indiandentalacademy.com

Cobalt & Iron Alloys
 The alloys of Co & Fe exhibit oxides of chromium under
normal implant surface finishing conditions after acid or
electro-chemical passivation.
 These chromium oxides as with Ti alloys result in
significant reduction in chemical activity &
environmental iron transfer.
 In general, if stainless steel implant surfaces are
mechanically altered during implantation or if the
construct induces an interface that is subjected to
biomechanical fretting, the iron alloy will biodegrade.
 However, in the absence of surface damage, the
chromium oxide on stainless steel biomaterials have
shown excellent resistance to breakdown & multiple
examples of tissue & host compatibility have been
shown for implants removed after long term
implantation.

Ceramics
 Aluminum oxide ceramics have been extensively
investigated related to surface properties and
how those properties relate to bone and soft
tissue integration.
 Ceramic coatings have been shown to enhance
the corrosion resistance & biocompatibility of
metal implants,in particular, surgical stainless
steel, ni-cr, co-cr alloys.
 However, studies in orthopedics cautioned that
the Al2O3 may cause demineralization
phenomenon caused by a high local
concentration of substrate ions in the presence
of metallic bone disease.

Hydroxy Apatite
 In addition to bulk, aluminum oxide biomaterials,
CaPO4 based ceramic or ceramic like coatings
have been added to Ti & Co alloy substrates to
enhance tissue integration.
 These coatings for the most part are applied by
plasma spraying small size particles of
crystalline HA ceramic powders.
 Surface roughening by particulate blasting can
be achieved by different media.
 Sandblasting provides irregular, rough surface
of 10microns.

 Ti implants maybe etched with a solution of Nitric
acid and Hydrochloric acid.
 The acids very rapidly attack metals other than
Ti & these processes are electrochemical in
nature.
 Proponents of this technique argue that implants
treated by sandblasting and acid-etch provide
superior radiographic bone densities along
implant inter phases compared with TPS

Titanium Plasma Spray
 Porous or rough Ti surfaces have been
fabricated by a plasma spraying a powder form
of molten droplets at high temperatures.
 At temperatures of 15000 deg centigrade an
argon plasma is associated with a nozzle to
provide very high velocity 600m/s partially
molten particles of Ti powder projected onto a
metal or an alloy substrate.
 Schroeder et al in animal experiments and
histologic studies, concluded that the rough and
porous surfaces showed a 3D interconnected
configuration likely to achieve bone-implant
attachment for stable anchorage.

Hydroxy Apatite Coating
 HA coating by plasma spray was brought to the
dental profession by DeGroot.
 Key et al showed with SEM & Spectrographic
analysis that plasma sprayed HA coating could
be crystalline and could offer chemical &
mechanical properties compatible with dental
implant applications.
 Cook et al measured the HA coating thickness
after retrieval from specimens inserted in
animals for 32weeks & showed a consistent
thickness of 50microns which is in the range of
advocated for manufacturing.

Other Surface Modifications
 Methods include controlled clinical reactions
with nitrogen or other elements or surface ion
implantation procedures.
 The reaction of Nitrogen with Ti alloys at
elevated temperatures results in Ti-Nitride
compounds being formed along the surface.
 Most Ti-Nitride surfaces are Gold in color & this
process has been extensively used for
enhancing the surface properties of industrial &
surgical instruments.

 Electrochemically the Ti-Nitrides are similar to
the oxides and no adverse electrochemical
behavior has been noted if the Nitride is lost
regionally.
 The Ti substrate re-oxidizes when the surface
layer of nitride is removed.
 Nitrogen implantation & carbon doped layer
deposition have been recommended to improve
the physical properties of stainless steel without
affecting its bio compatibility.

Surface Energy
 Measurements of surface property, values of an
implant’s ability to integrate within bone include
contact angle with fluids, local PH and surface
topography.
 An intrinsically high surface energy is said to be
most desirable. High surface energy implants
showed a 3fold increase in fibroblast adhesion
and higher surface energy surfaces such as
metals, alloys & ceramics are best suited to
achieve cell adhesion.
 Surface tension values of 40 dyne/cm & higher
are characteristic of very clean surfaces and
excellent biologic integration conditions.

 The shift in contact angle is related to
contamination of the surface by hydrophobic
contaminants & decreases the surface tension
parameters.
 A spontaneously deposited host dependent
conditioning film is pre-requisite to the adhesion
of any biologic element
 It is suggested that the wetting of the surface by
blood at the time of placement can be a good
indication of the high surface energy of the
implant.

Passivation & Chemical Cleaning
 The ASTM specifications for final surface
treatment of surgical Ti implants require pickling
and descaling with molten alkaline base salts.
 This is often followed by treatment with a
solution of nitric or hydroflouric acid to decrease
& eliminate contaminants such as iron.

Sterilization
 Manipulation with bare fingers, powdered
gloves, tap water can contaminate implant
surfaces.
 Today, most of the implants are available in pre-
sterilized form.
 Proteinaceous deposits & their action as films
can be best eliminated by RFGDT
 UV light sterilization after further evaluation may
be good alternative.
 Adequate sterilization of clean, pre-packed
dental implants & related surgical components
had resulted in an ever expanding use of Gamma
Radiation procedures.

Summary & Conclusion
 Dental Implantology in the 1960’s was judged to
be rather disorganized. Treatments provided
were said to be often not as successful as in
other specialty procedures like Orthopedic &
Cardiovascular Surgeries.
 This discipline evolved in 1970’s. The basis for
this was the successful use of synthetic bio
materials.
 Hence, the synthetic biomaterials have evolved
& are now constituted, fabricated & provided to
health care professionals as mechanically &
chemically clean devices that have high
predictability of success when used
appropriately within surgical disciplines.

References:
 Carl E Misch: Implant dentistry ( 2nd
edition)

THANK YOU

MATERIALS USED FOR DENTAL IMPLANT / dental implant courses by Indian dental academy

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MATERIALS USED FOR DENTAL IMPLANT / dental implant courses by Indian dental academy