An brief overview on implants and its systems with modifications

 Introduction
 History
 Osseointegration
 Biomaterials of implants
 Surface modification of
implants
 Macro surface
modifications
 Micro surface
modifications
 Nano surface
modifications
 Bio active surface
coatings
 Conclusion
 References

 Implant dentistry is unique because of its ability to
achieve an ideal replacement of the lost tissues,
regardless of the atrophy, disease, or injury of the
stomatognathic system.
 This has significantly increased the acceptance of
osseointegrated supported prosthesis by the
patients.
 However, greater the destruction of the
stomatognathic system, the more challenging is the
task of rehabilitation.

 As a result of the current availability of the
advanced diagnostic tools which aid in treatment
planning, the improved implant designs, materials,
and techniques as a result of continuous research,
many challenging clinical situations can be
successfully managed with predictable success.

Egypt, Early
civilizations &
Mayans
• Carved sea shells or stones
Middle ages
• Allografs & xenografts but failed due to
infections sometimes leading to death
Early implants
• During world war II by Dr. Norman Goldberg
in association with Dr. Aron Gershkoff
produced first sub-periosteal implant.

 One of the most important developments in dental
implantology occurred in 1957, when a Swedish
orthopedic surgeon by the name of Per-Ingvar
Brånemark began studying bone healing and
regeneration and discovered that bone could grow in
proximity with the titanium (Ti), and that it could
effectively be adhered to the metal without being
rejected.
 Therefore, Brånemark called this phenomenon
‘osseointegration’, and he carried out many further
studies using both animal and human subjects.

STAGES IN OSSEOINTEGRATION WITH
DIFFERENT CELLS

MECHANISM OF OSSEOINTEGRATION:
BLOOD CLOT
CLOT TRANSFORMED BY
PHAGOCYTES (1st to 3rd
day)
PROCALLUS FORMATION
(containing immature
fibroblasts and phagocytes)
DENSE CONNECTIVE TISSUE
(differentiation of
osteoblasts and fibroblasts)
CALLUS FORMATION
FIBROCARTILAGENOUS
CALLUS
BONY CALLUS (penetration
and maturation)

OSSEOINTEGRATION
BIOMATERIALS
IMPLANT
DESIGN
BIO-
MECHANICAL
FACTORS
SURFACE
CHARACTERISTICS
HEALTH & BONE
QUALITY
SURGICAL
TECHNIQUE

 Biomaterials are those materials that are
compatible with the living tissues.
 The physical properties of the materials, their
potential to corrode in the tissue environment,
their surface configuration, tissue induction and
their potential for eliciting inflammation or
rejection response are all important factors under
this area.

 The most critical aspect of biocompatibility is
dependent on the basic bulk and surface properties
and biomaterials.
 Materials used for fabrication of dental implants
can be categorized in two different ways:
 1. Chemical basis - metals, ceramics
 2. Biological basis - biodynamic materials: bio-
tolerant, bio-inert, bio-active

Classification -1
 Ablative/Subtractive processes-
E.g.: Grit Blasting, Acid Etching, Anodisation, Laser peening
 Additive processes-
E.g.: Plasma Spraying, Electrophoretic Deposition, Sol Gel coating, Biomimetic
precipitation
Classification -2
Based on texture obtained, the implant surface can be divided as:
 Concave texture: mainly by additive treatments like hydroxyapatite coating
and titanium plasma spraying.
 Convex texture: mainly by subtractive treatment like etching and blasting.

 Cp Ti and its alloys
 Grade I
 Grade 2
 Grade 3
 Grade 4
 Grade 5 - Ti 6Al 4V alloy
Cp Ti
Dental implants
Strength of cp Ti increases with increase in
oxygen content. Grade 4 is the strongest
unalloyed Ti.

 Biocompatibility of Titanium is due to the
formation of an oxide film(TiO2) over its surface.
 Grade 5 Ti alloy is strong and highly resistant to
fatigue and corrosion.
 Vanadium release from Ti6Al4V alloy is toxic and
can cause cytotoxicity and adverse tissue
reactions.
 Research is done to replace Vanadium with other
metals like Niobium(Nb) to reduce toxicity.

Body shape:
Cylindrical
Tapered
Cylindrical with tapered apex

 Straight, Divergent, Convergent

I. ‘V’ shaped
II. Buttress
III. Reverse buttress
IV. Square

 In a study by Ma et al. (2007), perfectly identical implants with
different thread helix (single, double and triple threaded) were
compared.
 These implants had a constant pitch of 0.8mm, although the double-
and triple threaded implants had twice and triple the thread helix of
the single-threaded implant, respectively.
 According to this FEA study, the most favourable configuration in
terms of implant stability appeared to be the single-threaded one,
followed by the double threaded.
 The triple threaded was found to be the least stable. It is suggested
that a faster insertion of implant may actually compromise the final
implant success.

 Thread depth is the distance between the
major and minor diameter of the thread.
 Thread width is the distance in the same axial
plane between the coronal most and the apical
most part, at the tip of a single thread.
 Both these designs have an effect on total
implant surface area.

 A 3D FEA using a V-shaped thread was created. Variations in
thread height and width were set with a range of 0.2–0.6mm
and 0.1–0.4mm, respectively.
 Forces of 100 and 50N were applied parallel to the long axis of
the implant and at a 45° angle.
 Results revealed that the optimal thread height ranged from
0.34 to 0.5mm and thread width between 0.18 and 0.3mm, with
thread height being more sensitive to peak stresses than
thread widths.
 In addition, maximum forces generated in cancellous bone were
significantly higher than those generated in cortical bone. Also,
45° non-axial loads had higher stress than axial loads (Kong55
et al. 2006).

 The neck of the implant is called crest module. Implant
companies lately have concentrated their research on
producing the best crest module features.
 This is because this area is where the implant meets the
soft tissue and changes from a virtually sterile
environment to an open oral cavity.
 Also, in this area the bone density is thicker (e.g.,
primary cortical bone) and therefore helpful to achieve
or maintain implant primary stability.

 Furthermore, this is also the force concentrated area
when the implant was put into function.
 If loading on a particular bone increases, the bone will
remodel to become stronger.
 If the loading on a bone decreases, the bone will become
weaker because no stimulus is present.
 Originally crest module was always smooth. The use of a
smooth neck on rough implants came from the attempt to
decrease plaque retention because the majority of the
implants coronal portion was not embedded in bone.

 When the smooth portion of the implant is placed under the
bone crest, increased shear forces are created resulting in
marginal bone loss and eventually more pocket formation
(Hanggi et al. 2005).
 Recently, the concept of microthreads in the crestal portion
has been introduced to maintain marginal bone and soft tissues
around the implants.
 Some authors attributed this bone loss to ‘disuse atrophy’
(Vaillancourt et al. 1995).
 In presence of a smooth neck, negligible forces are
transmitted to the marginal bone leading to its resorption.

 However, the presence of retentive elements at the
implant neck will dissipate some forces leading to the
maintenance of the crestal bone height accordingly to
Wolff’s law.
 In a 2D FEA, Schrotenboer et al. (2008) found
microthreaded implants increase bone stress at the
crestal portion when compared with smooth neck
implants.

 Machining (lathing, milling, threading) is not really a
surface treatment method, but on the other hand it can
be used to produce specific surface topographies and
surface compositions.
 Machined implant surfaces are generally characterized
by more grooves and valleys oriented along the machining
direction with the surface layers plastically deformed.
 The first generation of osseointegrated implants had a
relatively smooth machined surface.

 It is disadvantageous in the aspect that osteoblastic
cells are rugophillic—that is they are prone to grow along
the grooves existing in the surface.
 Hence a long waiting time between the surgery and
implant loading is necessary.
 Branemark’s protocol dictates 3-6 months healing or
waiting time prior to loading.
 Depending on the machining parameters, the mean
arithmetic roughness (Ra) values may range from 0.3 to
0.6μm when measured by optical or stylus prolifometry.

 Acid-etching of titanium dental implant, by immersing
it in strong acids (e.g., nitric acid, hydrochloric acid,
hydrofluoric acid, sulfuric acid, and their mixtures)
for a given period of time, creates a micro-roughness
of 0.5–3 μm.
 The surface is pitted by removal of grains and grain
boundaries of the implant surface, as certain phases
and impurities are more sensitive to the etching. It
also cleans the implant surface, e.g., removes deposits.

Solvent cleaning:
 It is mainly aimed at cleaning the surface of the implant from
oils, greases and fatty surface contaminants remaining after
manufacturing process by using organic solvents, surface active
detergents and alkaline cleaning solutions.
 This process does not have any effect on the surface of the
implant.
 Solvent selection is based on the type of material and
contamination to be cleaned.

Alkaline etching:
 It is a simple technique to modify titanium surfaces.
 Treatment of titanium in 4-5 M sodium hydroxide at
600°C for 24 hours has been shown to produce sodium
titanate gel of 1 μm thick, with an irregular topography
and a high degree of open porosity.
 Composition and structure of this layer can be further
modified by proper heat treatment.
 When the alkali treatment is preceded by etching in
hydrochloric acid/sulfuric acid, porosity of the final
surface is found to increase.

 Passivation treatments are used for obtaining a uniformly
oxidized surface to improve corrosion resistance.
 It is often the last step in the surface preparation of the
implants.
 Immersion of titanium for a minimum of 30 minutes in 20-
40 vol% solution of nitric acid at room temperature is the
most commonly employed method.
 After passivation, surface of the implant should be
neutralized, thoroughly rinsed and dried.
 Nitric acid passivation has no major influence on the overall
surface topography of titanium surfaces.

 These broadly consist of anodic and cathodic
treatments.
 Anodic oxidation is the chief anodic technique.
 Electrophoretic and cathodic HA depositions are the
cathodic techniques.
Anodic oxidation/Anodization:
 The anodic oxidation of titanium is categorized by solid
state diffusion in the oxide or by dissolution deposition
in the electrolyte.

At Ti/Ti oxide interface:
Ti → Ti2+ + 2e－
At Ti oxide/electrolyte interface:
2H2O → 2O2 + 4H+
(oxygen ions react with titanium to
form oxide)
2H2O → O2 (gas) + 4H+ + 4e－
(oxygen gas evolves)
At both interfaces:
Ti2+ + 2O2－ → TiO2 + 2e－

 The titanium and oxygen ions formed in these redox
reactions are driven through the oxide by the
externally applied electric field, leading to growth of
the oxide.
 The oxides usually grow at the rate of 1.5 – 3 nm/V
(also called as growth constant) in the various
electrolytes.
 BIOCOAT (colour anodization)
 By this process titanium is immersed into an
electrolyte and connected as an anode leading to the
formation of an oxide film at the surface.

 The oxide film acts as an interferential filter leading to
beautiful colours varying in the same sequence as the
rainbow when the voltage is increased.
BIODIZE (alkaline grey anodization)
 This process is similar to the Biocoat however the
specific electrolyte allows the formation of thicker
TiO2 layers in the range of micrometers.
 This process has originally been developed for
aerospace applications.

BIOBRIGHT (electropolishing)
 In this process titanium is immersed into an electrolyte
and is connected as an anode leading to the dissolution of
the titanium material.
 However, due to the explosive nature of percholate (used
as electrolyte), the process did not find large-scale
industrial applications.
 Innosurf is a modification of the Biobright process which
eliminates the use of perchlorate and hence also the
danger of explosion. The removed layer of titanium is in
the range of 5 to 30 micrometers.

ELECTROPHORESIS:
 Electrophoretic deposition (EPD) of HA represents an
important technological process because of its simplicity
and low cost of the process.
 Advantages also include ability to coat with uniform
thickness, wide range of thicknesses, ability to coat
complex shapes, and ease of chemical composition
control.
 These coatings have strong adhesion to the substrate
and are mainly composed of pure phases without any
metastable or mixed phases.

Mechanism:
 There are two steps involved in electrophoretic deposition.
 The first step involves the migration of particles (which
acquire positive charge) under the influence of an electric field
applied to a stable colloidal suspension.
 The second step involves the deposition on the metallic
substrate.
 Driving force of the deposition process is the applied electric
field.
 Depending on the mode and sequence of voltage applied, the
electrophoretic deposition can be carried out at
 i) constant voltage or
 ii) dynamic voltage.

1. Electrophoresis at constant voltage
 HA suspensions in polyvinyl alcohol and N,Ndimethyl
formamide were used and coatings were obtained on
titanium by applying voltages in the range of 10-200V.
2. Dynamic voltage electrophoresis
 Using dynamically applied voltage a method was
developed to produce a gradient structure, in which the
part of the layer attached to the substrate is dense,
while the outer layer is porous.

3. Electrochemical cathodic deposition
 In this method, calcium phosphate coatings are formed on
the titanium cathode from a bath containing dissolved
calcium and phosphorus compounds.
 This process is characterized as a procedure performed
using the ambient temperature that results in good
conformability to the shape of the component.
 These coatings also exhibit a control over crystallinity
under milder conditions and shorter reaction times.
Furthermore, a film thickness of less than 1μm can be
achieved.

Laser Peening:
 A recently developed method; claiming no contact, no
media and contamination free.
 High intensity (5-15 GW/cm2) nanosecond pulses (10-
30ns) of laser light beam (3-5mm width) striking the
ablative layers generate short-lived plasma which causes a
shock wave to travel into the implant.
 The shock wave induces compressive residual stress that
penetrates beneath the surface and strengthens the
implant, resulting in improvements in fatigue life and
retarding in stress corrosion cracking occurrence.

Plasma Spraying
 Plasma-spraying is commercially the most frequently
used method for deposition of calcium phosphate
coatings, such as HA, onto implant materials to
improve their bioactivity.
 The thickness of hydroxyapatite coatings produced
by plasma-spray varies from 100 to 300 μm

Sputter Deposition
 Sputtering is a process whereby atoms or molecules of a
material are ejected in a vacuum chamber by
bombardment of high-energy ions.
 There are several sputter techniques and a common
drawback inherent in all these methods is that the
deposition rate is very low and the process itself is very
slow
 The deposition rate is improved by using a magnetically
enhanced variant of diode sputtering, known as radio
frequency magnetron sputtering.

Electrophoretic Deposition:
 Electrophoretic deposition is a process in which colloidal
particles such as hydroxyapatite nano-precipitates which
are suspended in a liquid medium migrate under the
influence of an electric field and are deposited onto a
counter charged electrode.
 The coating is simply formed by pressure exerted by the
potential difference between the electrodes. The
operational parameters of EPD can be changed to alter
HA surface coating morphology and composition.

 Advantages
 low cost, simple methodology, capable of producing coatings of
variable thicknesses, high deposition rate, formation of highly
crystalline deposits with low residual stresses, ability to coat
irregularly shaped or porous objects such as threaded implants
due to its high throwing power.
 Disadvantages
 Need for post deposition heat treatment to increase the density
of the coating. Conventional feed stocks require temperatures of
at least 1200˚C to be densified.
 Temperatures above 1250˚C affect the oxide layer and
mechanical properties of stainless steel or Ti alloy, as well as
decompose HA affecting the interfacial strength between metal
and coating.

Sol- Gel Coated Implants:
 The sol-gel method represents a simple and low cost procedure
to deposit thin coatings with homogenous chemical composition
onto substrates with large dimensions and complex design.
 The sol-gel and electrophoresis methods are capable of
improving chemical homogeneity in the resulting HA coating to
a significant extent, when compared to conventional methods
such as solid state reactions, wet precipitation and
hydrothermal synthesis.
 These methods are also simple and less expensive than the
plasma spraying method that is widely used for biomedical
applications.

 During surgery, blood vessels are injured and thus,
dental implant surfaces interact with blood components.
 Various plasma proteins get adsorbed on the material
surface within a minute.
 Platelets from blood interact also with the implant
surface.
 Plasma proteins modify the surface while activated
platelets are responsible for thrombus formation and
blood clotting.
 Plasma contains dissolved substances such as glucose,
amino acids, cholesterols, hormones, urea, and various
ions.

 All of these blood substances interact with implant
surface thus modifying their chemical properties like
charge or hydrophobicity.
 Blood interactions with implants lead to protein adsorption,
which is dependent on the surface properties of the material
and occurs through a complex series of adsorption and
displacement steps known as the Vroman effect.
 A hydrophilic surface is better for blood coagulation than a
hydrophobic surface.
 Consequently, dental implants manufacturers have developed
high hydrophilic and rough implant surfaces which in turn
exhibited better osseointegration than conventional ones.

 Adsorption of proteins such as fibronectin, vitronectin
on surface of dental implants could promote cell
adhesion by cell-binding RGD domain (arg–gly–asp).
 This RGD sequence interacts with integrin present on
the cell membrane.
 Interactions between cell membrane integrins and
proteins coated onto implant surface play a key role in
adhesion of many cells types.

Organic nanoscale self-assembled monolayers (SAM)
 This technique involves adsorption and self-assembly of
single layers of molecules on a substrate.
 Molecular self-assembly of alkane phosphate SAMs on
metal oxides like TiO2 and Al2O3 have been reported.
 The hydrophilicity of these alkane phosphate SAMs can
be modified with a hydroxy-terminated end group.

 An in-vivo study was performed with titanium surface
with three coatings: self-assembled monolayer of
phosphonate molecules (SAMP), RGD peptide, and HA.
 Histological analysis showed abundant new bone
formation around all of the three groups, though higher
enhanced formation was apparent in the SAMP group.
 Such studies showed that SAMs could be used to control
the physicochemical properties (e.g., wettability) and
biochemical composition of titanium surface to influence
the response of host tissue.

Hydrogels on Titanium:
 A hydrogel is a network of polymer chains that swell in
aqueous solution.
 It is composed of long polymer chains connected by
cross-links.
 The cross-links may be biodegradable or non-
biodegradable and are formed by ionic interactions
between polyelectrolyte chains.
 Cross-linking of polymer molecules or polymerization can
be achieved by photo-polymerization, changes in
temperature, radiation, self-assembly, or cross-linking
enzymes.

 These key characteristics along with the ease of in-situ
fabrication have made hydrogels a biomaterial of choice in
in-vitro studies for analyzing cell–biomaterial interactions
and in biomedical applications.
 They are used as carrier scaffolds for guided bone
regeneration (GBR) using osteogenic growth factors.
 Although many polymer hydrogels have been studied,
polyethylene glycol hydrogel (PEG) is one of the most widely
investigated systems. PEG hydrogel can be fabricated into
three-dimensional microstructures to study the response
of cells for their applications in tissue engineering.

Titanium Nanotubes:
 Successful chemical synthesis of titanium dioxide (TiO2)
nanotubes by anodization technique was reported.
 A completely different growth morphology leading to
self-organized and ordered nanotubular,
 nanoporous structures of TiO2 has been obtained when
electrolytes containing fluoride ions and suitable
anodization conditions were used.
 These nanotube-like pores possess higher surface energy
and wettability compared to un-anodized titanium.

 Furthermore, it has been suggested that TiO2 with a 3-D
nanoporous structure may enhance hydroxyapatite
formability when compared to dense TiO2.
 When the anodized titanium substrates were placed in
simulated body fluid (SBF), bone-like apatite layer was
formed on TiO2.
 These studies indicate that nanotubular, nanoporous
TiO2 structures can simulate the environment where
bone formation/remodeling occur.

(A) acidic fluoride or HF electrolytes (B) glycerol/fluoride electrolytes, (C)
ethylene glycol/fluoride electrolytes. (D) Tubes grown by a different
approach: rapid breakdown anodization (RBA)

1. Bio-active glass coating:
 Originally introduced by Hench (1971), silica-based
bioactive glasses are slowly resorbing synthetic
osteoconductive materials which are able to form strong
chemical bond with bone.
 Several experimental studies have shown that titanium
implants coated with bioactive glass (BAG) were
integrated into host bone without a connective tissue
capsule and significantly greater osseointegration and
high removal torque in comparison to the control
uncoated titanium implants.

 Also significantly higher bone-implant contact was
observed for BAG coated titanium implants than those in
both the uncoated and HA coated titanium implants after
4, 12, and 24 weeks of healing (Xie et al., 2010).
2. Hydroxyapatite (HA) coating:
 HA has a porous structure and naturally forms a rough
surface, which is ideal for osseointegration. Hence, no
roughening treatment, such as sandblasting, is necessary
for HA.

 HA coating has two major advantages.-
 Faster osseointegration leads to earlier stabilization of
the implant in surrounding bone. Thus, healing time is
reduced, and the final crown or bridge can be placed
earlier on the implant.
 Stronger bonding between implant and bone extends the
functional life of the prosthesis. These benefits can
greatly improve the success rate of dental implantation,
especially in patients with poor bone qualities.

3. Calcium-Phosphate coating:
 Accelerates bone formation around the implant and produces
effective osseointegration.
 However, the longevity of the coating for an optimal bone
apposition on to the implant remains controversial.
4. Titanium Nitride Coatings:
 Commercially available treatment is known as Plasma nitriding
or PVD coating with TiN.
 Titanium nitride has high surface hardness and mechanical
strength.
 Titanium nitriding is an effective way to increase corrosion
resistance and surface hardness of the exposed implant
surfaces (abutment part or mucosa penetration part).

5. Fluoride Treatment:
 Titanium is very reactive to fluoride ions, forming soluble
TiF4.
 The chemical treatment of titanium in fluoride solutions
enhances the osseointegration of dental implants.
 It has been shown that this chemical surface treatment
enhances osteoblastic differentiation in comparison with
control samples.
 Fluoridated rough implants also withstood greater push-
out forces and showed a significantly higher removal
torque than the control implants.

6. Biologically Active Drugs:
 Bisphosphonates
 Simvastatin
 Antibiotic Coating
 Gentamycin
 Tetracycline-HCl

The surface roughness values produced in each type
of surface modification technique-

 Implant material- Grade 4 cp Ti
Cold worked cp Ti (high strength)
• Body shape - Tapered
• Threads -Buttress/ V shaped
• Surface - Ti Unite surface
(Anodization)

 Implant material- Grade 5 Ti
alloy (Ti6Al4V)
• Body shape - Tapered/ cylindrical
• Threads - square/ buttress
• Surface - Resorbable blast
textured HA coated

• Threads - Buttress
Bioprofile threads
(3 different thread designs)

• Surface - Nanopore surface (cacium
oxidized nano surface with 11% Ca
deposits)

• Body shape - Tapered/ cyindrical
• Threads - ‘V’ shaped, corkscrew thread
• Surface - SA surface
HA surface
RBM surface

 Implant material- Grade 23 Ti/
 Ti6Al4VaELI
Higher purity version of Grade 5
Outer layer is pure TiO2 layer.
• Body shape - Tapered/ cylindrical
• Threads - buttress/ ‘V’ shaped
Dual thread design

Micro rings at neck
• Surface - sand blasted , acid etched

 Implant material- Grade 5 Ti alloy
• Body shape - cylindrical / Tapered
• Threads - ‘V’ shaped
• Surface - SLA surface
TPS/HA coated

 Implant material- Grade 23 Ti/
Ti6Al4VaELI
• Threads - ‘V’ shaped / square
Dual threads

-‘Wing’ threads in Saturn implants
used in immediate extraction cases
• Surface- Sand blasted, acid etched

• Threads - Magic threads (reverse
triangle thread)
‘S’ shaped neck for bioseal
RBM surface

Osseofix surface (RBM)

 Implant material- Grade 5 Ti alloy
Triple thread design
• Surface - Wet shot blasting, acid
etched
RBM surface

 Which implant system to choose?
 The decision maker is “YOU”.
Along with all the considerations
mentioned, an analysis of the success
rate studies , feasibility, availability,
prosthetic range, etc should be
looked in before selecting an implant
system

1. Contemporary Implant Dentistry-carl E. Misch
2. Dental Implants, The Art And Science-charles A.
Babbush
3. Practical Implant Dentistry- Arun K. Garg
4. The Branemark System Of Oral Reconstruction-
Richard A.
5. Prosthodontic Treatment For Edentulous Patients –
Complete Dentures & Implant Supported Prosthesis –
Zarb – Bolender.
6. Dental Implant Prosthetics – Carl E . Misch

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