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RECENT ADVANCES IN DENTAL IMPLANTS AND
MATERIALS-A REVIEW
1 Dr. Nikhil Bhalchandra Awale, 2 Dr. Girish Suragimath, 3 Dr. A.
Siddhartha Varma, 3Dr. Sameer A. Zope, 4 Dr. Apurva A. Pisal
1,2,3,4 Department of Periodontology
2 Professor and Head of the Department
3 Reader, 4 Senior Lecturer
1,2,3,4 School of Dental Sciences, Krishna Institute of Medical Sciences
Deemed to be University, Karad, Maharashtra, India.
Email Address: nikhil.awale01@gmail.com
drgirishsuragimath@gmail.com
siddhartha_varma@yahoo.co.in
aoldentist@gmail.com
apurvapisal@gmail.com
Abstract
Tooth loss is very a very common problem; therefore, the use of dental implants is also a common practice.
Although research on dental implant designs, materials and techniques has increased in the past few years and is
expected to expand in the future, there is still a lot of work involved in the use of better biomaterials, implant design,
surface modification and functionalization of surfaces to improve the long-term outcomes of the treatment. This
paper provides a brief history and evolution of dental implants. It also describes the types of implants that have been
developed, and the parameters that are presently used in the design of dental implants. Finally, it describes the trends
that are employed to improve dental implant surfaces, and current technologies used for the analysis and design of
the implants.
Key words: Dental implants, History, Design, Surfaces modifications, Osseointegration, advances.
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INTRODUCTION
Missing teeth is a health problem associated with functional, cosmetic and psychological morbidity. The
most common cause of tooth loss is Periodontitis but it can also result due to many disease processes or
following any dental trauma, 1 other causes include dental caries, trauma, developmental Defects and
genetic disorders. That is when dental implants play a role in providing replacement of missing teeth/tooth
and restoring the function along with esthetic support in most. Dental implants have become an
increasingly common & reliable treatment option in clinical practice as loss of teeth is very common. Tooth
loss not only impairs quality of life but also indirectly affects the wellbeing of the individual. The missing
teeth affects the day to day activities of individuals like chewing, ability to talk (speech) which results in
low self-esteem, loss of confidence, less social interactions and thus hampers the work and daily
activities.2,3 The science of dental implantology is highly dynamic. It has not only undergone numerous
modifications and improvements after it was first introduced into the field of dentistry by Dr. Branemark
but also has proven to be a boon in disguise to the society with each improvement and advancement made
in the field
HISTORY 4
The desire to replace missing teeth with something similar to the root of a tooth dates back thousands of
years and includes civilizations such as ancient Chinese, Egyptians, Greeks and Etruscans. History has
revealed a ferrous metal tooth in a skull found in Europe which dated back to the time of Christ. Also it is
well known that the Incas from Central America used pieces of sea shells to replace missing tooth. While
the Chinese tapped them into the bone underlying the missing tooth. History shows then that it has always
made sense to replace a tooth with an implant in the approximate shape of a tooth. The first prototype of the
hollow cylinder implants used today was introduced in 1906 by Greenfield and was made of an iridium-
platinum alloy. The reaction of the underlying bone toward s the metal implant and the tolerance of tissue
was given importance in the early 1930s. Strock succeeded in anchoring a Vitallium (cobalt-
chromiummolybdenum alloy screw) within bone and immediately mounting a porcelain crown to the
implant. At the same time, Muller placed the first implant, made of an iridiumplatinum alloy into the oral
cavity. From the 1950s, numerous implantologists developed implant procedures. The first step in the field
of modern implantology was taken by a physician named Per-Ingvar Branemark. He conducted
experiments in vivo using Titanium chambers by placing them within the bone, discovered the particular
connection this metal was able to develop within the recipient tissue. In 1965, Branemark proposed a
‘‘bone-anchored bridge’’ to treat edentulous mandibles. The first-hand knowledge about osseointegration
as we know today was highlighted in two publications. Branemark in his study on rabbits observed firmly
attached titanium implant. Furthermore observation after a year showed absence of inflammation in the
peri-implant area bone. Also the soft tissue was found to have formed an attachment to the metal and bone
to the titanium. Even if the osseointegration was not accepted as a clinical achievement and was regarded
as impossible by many, the Branemark system of dental implants was introduced in 1971. Nowadays, the
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most frequently used implant material is Titanium and zirconia. As a result of Branemark’s extensive
studies, Titanium has become the gold standard in implant dentistry. However, the great revolution in the
field of ceramic materials with the use of zirconium dioxide and also other are in progress.
IMPLANT DESIGN
In order to fit the current surgical concepts and also for better patient care numerous implants with
difference in shape and size have evolved. Also, research on implant has revealed that even a subtle change
in the dimensions of the implant could have an influence on the rate of success of the implant.
1) Shape (Geometry)5
In the design of the implant the shape has an important role as the surface area of the implant and the
geometry affects not only the bone-implant interaction but also decides the distribution of forces and
ultimately the implant stability. The main types of implants are cylindrical, conical, stepped, screw
shaped, and hollow cylindrical. The tapered implants are widely used as it results in lateral
compression of bone and increased stiffness of the interfacial bone, which is reported to increase the
implant primary stability.
2) Threads6-8
The implant macro-structure is represented as threaded or non-thread out of which the threaded type is
the most commonly used implant design.There are four thread shapes which are most regularly used
when a dental implant is described. These are V-shaped, square-shaped, buttress thread and reverse
buttress threads.
Thread pitch- it is measured in an axis parallel to the screw. It is the distance from the center of the
thread to the center of the next thread.
In a single-threaded screw lead is equal to pitch, however in a double threaded screw, lead is double
the pitch and in a triple-threaded screw lead is triple the pitch. An implant with double threads would
insert twice as fast the single threaded and the triple threaded would only need a third of the required
time for a single thread
3) Length5
The dimension of an implant from the platform to the apex is referred as implant length. Most common
lengths are between 8 and 16mm which correspond quite closely to normal root length.The primary
stability of the implant is directly proportional to the length of the implant and surface contact. Thus
implants with long length and large surface area are preferred so as to dissipate the occlusal forces in
order to prevent interface stress and ultimately implant success..9 Over the years, commercially
available 7mm implants (usually the shortest on a company’s lineup) reported higher failure rates
compare to 8.5mm, 10mm and 11.5mm implants.10
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4) Diameter
The diameter of an implant is the dimension from the peak of the widest thread to the same point on
the opposite side of the implant.According to the diameter, implants may be classified as mini when
diameter is ≤2.7 mm,narrow when the diameter is >2.7 mm,regular when it ranges from 3.75−5 mm;
and wide when the diameter is >5 mm.It would be ideal to choose an implant with the diameter similar
to the root of the tooth being replaced.
a. Wide implant is indicated in following criteria
i. Poor quality bone;
ii. Adequate mesio-distal and bucco-lingual width but limited ridge height
iii. Immediate implant placement (after tooth extraction).
b. Narrow implant is indicated in following criteria
i. Mandibular or maxillary incisor replacement
ii. Limited edentulous space;
iii. Limited width of ridge (to avoid ridge augmentation surgery);
iv. Good emergence profile not achievable with a wide implant body.
v. Converging adjacent tooth roots
MODIFICATIONS OF HEX DESIGNS
EXTERNAL HEX10
The external hex type is the original prosthetic connection for the dental implants Designed by Dr.
Branemark. It is the most common type of prosthetic attachment and has proven to be a stable
prosthetic attachment for all kinds of restorations.
FEATURES: External hex has 0.7mm standard hexagon.
INTERNAL HEX
An internal hex type is a fairly common attachment with a greater stability due to its longer hex. It is
also more expensive compared to the external hex and patent rights are constantly being argued in the
market. FEATURE: 7-mm-deep hex below a 0.5- mm– wide, 45° bevel that distribute intraoral forces
deeper within the implant to protect the retention screw from excess loading.
MORSE TAPER
Internal tapered attachments allow for an abutment to be friction seated into the head of the implant
fixture. It is simpler to use because there are no screws.
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FEATURE: Tapered abutment post is inserted into the non-threaded shaft of a dental implant with the
same taper.
SPLINE10
The spline has proven to be more stable than other types with respect to anti-rotation. Its main
limitation is the weak resistance to lateral force.
THE ABUTMENTS11,12
The restorations that consist of crowns or fixed prostheses (bridges), and that are supported by
implants. There are seven types of abutments available for use in single and fixed implant supported
restorations.
I. CUSTOM-MADE ABUTMENTS
As per the requirement they may be made with or without a metal machined interface ring on
a wax or plastic pattern.Universal castable long abutments (UCLA) plastic patterns are an
example of these types of abutments
II. PRE-MACHINED (PREFABRICATED/READY-MADE)MODIFIABLE METAL
ABUTMENTS
They are prefabricated abutments that are adjustable and modifiable intra- and extra-orally
III. PRE-MACHINED (PRE-FABRICATED/READY-MADE), NON-MODIFIABLE
METAL ABUTMENTS
They are pre-fabricated abutments that cannot be modified or altered.
IV. ALL-CERAMIC ABUTMENTS
They are made entirely of ceramic that are densely sintered high-purity alumina (Al2O3)
ceramic
V. CAD/CAM MILLED ABUTMENTS
They are made from a block of titanium or ceramic and are customized according to the need.
VI. ANGULATED ABUTMENTS
The angulated abutments facilitates paralleling non-aligned dental implants where Inclination
range from 10-350 degree
VII. MULTI-UNIT ABUTMENT
In situations with greater dis-angulation, the angulated abutment is used which is one piece.
IMPLANT SURFACE CHARACTERISTICS
The surface properties of materials are regarded as decisive for the tissue response in association with
materials. There are three different properties as follows:
I) Mechanical properties.
The mechanical techniques induce the shaping of material surfaces by physical forces.
II) Topographic properties13
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The surface topography refers to the orientation of the surface irregularities and the degree of
roughness of the surface.
A. Based on the surface roughness14 (Wennerberg and coworkers)
1. Smooth surfaces: (Sa value < 0.5 μm)
(E.g. polished abutment surface).
2. Minimally rough surfaces: (Sa = 0.5-1.0 μm)
(E.g. turned implants).
3. Moderately rough surfaces: (Sa = 1.0-2.0 μm)
(E.g. most commonly used types).
4. Rough surfaces: (Sa > 2.0 μm).
(E.g. plasma sprayed surfaces)
B. Based on texture obtained
1. Concave texture: mainly by additive treatments like hydroxyapatite coating and titanium plasma
spraying.
2. Convex texture: treatment which is subtractive like blasting and etching.
C. Based on the orientation of surface irregularities.15
1. Isotropic surfaces: irrespective of the measuring direction the topography remains the same.
2. Anisotropic surfaces: as the name suggests it has difference in the roughness and have clear
directionality.
D. Based on morphological properties
1. Physicochemical: modification of surface energy, surface charge and surface composition to
improve the bone implant interface.
2. Morphological:alteration of surface morphology and roughness to influence cell and tissue
response to implants.
3. Biochemical:increased biochemical interaction of implant with bone
1) MACHINING16
The surface of the implant is untreated because at first the implant after being manufactured is subjected to
cleaning, decontamination, passivation followed by sterilization without any post sterilization finishing.
The implants that are machined are found to have more number of grooves and valleys making scope for
bone interlocking due to mechanical resistance.
2) TITANIUM PLASMA SPRAYING (TPS)17
In this method the powdered form of substances like titanium or calcium phosphate are projected onto the
roughened surfaces following heating at very high temperatures. This formsa coating on the surface of the
implant. The coating is of30 μ m to 50 μ m thickness. This procedure not only imparts a rough surface to
the implant but also increases the surface area.
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The increase in the surface area is upto 6 times. A 30μm thick film is formed on the surface of the implant
when the titanium particles are projected on to the surface wherein they undergo condensation followed by
fusion.
3) GRIT-BLASTING17
In this method the alterations in the surface are made by projecting hard particles of alumina and TiO2
at very high velocities thus imparting roughness to the surface. The degree of roughness is not only
dependent on the size of the particles, pressure of projection, time of blasting but the distance of the
implant surface from the source of particle. Hard ceramic or metallic particles are preferred for grid
blasting of titanium surfaces to be roughened. This method allows for improved adhesion thus
allowing for proper and timely proliferation and differentiation of osteoblasts. The only limitation of
this procedure being the residual particles being left out on the implant surfaces following the blasting.
4) ACID-ETCHING18,19
This method employs the technique of immersing the metallic implant into an acidic solution (HCl or
HF) thus increasing the thickness of the oxide layer and ultimately producing roughness due to
emergence of micropits onto the surface. The micropits range in size from 0.5 – 2 μm. The factors
which have an effect on this technique include the procedure time, temperature at which the procedure
was conducted and last but not the least the concentration of the acid used. The implant thus obtained
is found to have better and rapid ossteointegration as a result of improved homogeneous roughness,
improved cell adhesion and increased surface area. The implants which have been acid etched are
found to have better implant stability quotient as compared to the machined screws using a polymer to
simulate bone.
Modification techniques to enhance osseointegration
Dual acid-etched technique-
In this technique the implants are immersed in a mixture of two acids which are heated above 100 °C.
The acids produce micro rough surface. Commonly used acids include concentrated HCl and H2SO4
Sandblasted and acid etched surface (SLA)-
This technique is combination of two techniques which is sandblasting and acid etching. In
sandblasting the dental implants are sandblasted with large grits 250-500 μm. This makes the surface
rough. Now this is followed by acid etching using concentrated HCl and H2SO4. Following this the
surface is not only micro textured but also cleaned.
5) ANODIZATION20
This technique employs use of electrochemical energy wherein the implant is immersed in an
electrolyte solution and current is passed through the solution. The result is generation of micropores
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of various diameters along with increase in the oxide layer. The advantage of this technique being the
strong reinforcement of bone response as compared to the machined surfaces
Method for titanium implants anodisation
a) Acid (Sulphuric acid)
b) Non-acid electrolytes like
i. Sodium phosphate and Isopropyl phosphate in Ethylene glycol
ii. Ammonium pentaborate
iii. Calcium acetate and Calcium Glycerophosphate.
The oxides usually grow at the rate of 1.5 – 3 nm/V (also called as growth constant) in the various
electrolytes.
Bio-coat - (Color anodization)
Titanium is immersed into an electrolyte and connected as an anode leading to the formation of an
oxide film at the surface.
Bio-dize - (Alkaline grey anodization)
Similar to the Bio coat however the specific electrolyte allows the formation of thicker TiO2
layers in the range of micrometers.
Bio-bright - (Electropolishing)
Titanium is immersed into an electrolyte and is connected as an anode leading to the dissolution of
the titanium material
Innosurf - Modification of the Bio bright process. The removed layer of titanium is in the
range of 5 to 30 micrometers.
6) LASER TREATMENT21-23
Since its inception it has gained popularity in the dental field. The dental lasers are used for the
purpose of cleaning and sterilizing the implant. The underlying mechanism of decontamination being
physical property of laser along with its interaction with the tissue as aresult of scaterring, reflection,
absorption as well as elevation of temperature. The process involves use high intensity (5-15 GW/cm2)
nanosecond pulses (10-30 ns) of a laser beam striking a protective layer of paint on the metallic
surface. This creates a shock which transverses the implant and as it does so it improves the strength of
the implant and thus fatigue life and decreasing the chances of corrosion cracking. Numerous types of
lasers are available viz. argon ion, ruby, CO2, Nd:YAG, and excimer lasers. Of these the most preferred
being Nd:YAG laser.
7) RESORBABLE BLAST MEDIA (RBM)
Resorbable blast media (RBM) surface is formed by blasting the implant surface by only a
biocompatible material, Calcium phosphate ceramic that is fully resorbable, permitting its removal
after manufacturing resulting in a pure, clean textured titanium surface. The roughening process does
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not involve acid-etching. Hence, the RBM implant surface is free from acid-etching residues. It is also
not susceptible to titanium grain boundary degradation that can occur from aggressive acid etching
procedures.It produces a surface roughness of 20 to 25 μm. Life Core RBM implant is one such
implant.
8) ELECTROPHORETIC DEPOSITION (EPD)
EPD is a process in which colloidal particles, such as HA 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 major disadvantage of EPD is the need for post deposition heat treatment to densify the
coating.
9) OTHER CHEMICAL TREATMENTS
SOLVENT CLEANING
Removes oils, greases and fatty surface contaminants remaining after manufacturing process.
Organic solvents (aliphatic hydrocarbons, alcohols, ketones or chlorinated hydrocarbons),
surface active detergents and alkaline cleaning solutions.
ALKALINE ETCHING
A 1 μm thick gel of sodium titanate can be obtained when titanium with high degree of open
porosity and irregular topography is obtained when it is treated with 4-5 ML sodium
hydroxide at 600°C for 24 hours. Boiling alkali solution (0.2 ML sodium hydroxide, 1400°C
for 5 hours) produce a high density of Nano scale pits on the titanium.
PASSIVATION TREATMENTS
For obtaining a uniformly oxidized surface to improve corrosion resistance. Immersion of
titanium for a minimum of 30 minutes in 20-40 volume percentage solution of nitric acid at
room temperature. It is important to neutralize the implant after passivation. This can be
achieved by thoroughly rinsing and drying the implant.
10) . VACUUM TREATMENT
Glow-discharge treatment (cold plasma treatment): this method employs the use oflow-
pressure electrical discharge onto the surface of the implant. Two types of treatment options
available are plasma deposition method and plasma surface modification.
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In Plasma deposition – in this method a glow discharge is used to deposit the coating
material from a separate solid target (sputter deposition) and/or by reactions in the gas phase
(reactive sputtering or plasma polymerization).
In Plasma surface modification – in this method the exposure of sample surface to a glow
discharge id done so as to obtain a specific modification of the properties of surface.
In Ion implantation method – in this method the surface of the implant is bombarded with
high energy ions of approximately 100 KcV to 1 McV range. Here the ions penetrate the
surface of implant to typical depths of approximately 0.1-1μm.
III) PHYSIOCHEMICAL PROPERTIES.
Refer to factors such as surface energy¸ surface charge and surface composition. A surface with a high
energy has affinity for adsorption. In other words, an oral implant with high surface energy may show
stronger Osseo integration.
There are two broad types of chemical alterations:
A) ADDITION OF ORGANIC PHASES (GROWTH FACTORS)24
A number of growth factors has been tested for their effects on bone formation and implant
osseointegration.25,26
a) BONE MORPHOGENETIC PROTEINS (BMPs)27-30
Bone morphogenetic proteins (BMPs), members of the transforming growth factor
(TGF)-superfamily, are well known to be osteo- and chondro-inductive. BMPs are widely
used as an additive for bone graft material; its addition contributes for bone to implant
contact (BIC).In various studies the usage of BMP reported to improve and enhance
osteogenesis process, osteoblasts activity, chondroblast activity and osseointegration after
dental implantation. The applications of BMPs on Ti surface can improve the
osseointegration of dental implants and shorten the time period for implant integration.
b) PLATELET-DERIVED GROWTH FACTORS (PDGFS)
Platelet-derived growth factor as the name suggests are derived from platelets and are
found to have a role in the growth and development of not only bone cells but also tissue
of mesenchymal origin like the periodontal ligament31.
It not only plays an important role in vascular growth but also in healing of soft tissue
and this is achieved by promoting angiogenesis.32
c) TGF-8 (TRANSFORMING GROWTH FACTOR-BETA)
Transforming growth factor –beta plays a pivotal role in regulation of not only growth
but differentiation of tissue of bone origin, connective tissue. It also regulates the
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immunological system. Due to all these factors study by Lind et al on dogs found it to be
enhancing the mechanical fixation implants in bone along with enhancing ingrowth.
d) FIBROBLAST GROWTH FACTORS (FGFS)
The mesodermal and neuroectodermal origin tissue are regulated by fibroblast growth
factors. At present it consists of 7 members. They are found to have osteogenic as well as
angiogenic properties. Thus making them candidates for future prospects.
e) INSULIN GROWTH FACTORS (IGFS)
These are polypeptides which are synthesized by various tissues including the bone
tissue. They have been attributed in the growth of collagen tissue and may be beneficial
in increasing the bone mass when incorporated with the dental implant
B) ADDITION OF INORGANIC PHASES (HYDROXYAPATITE)33-38
Varying percentage of crystalline Hydroxyapatite, amorphous calcium phosphate and ßtricalcium
phosphate (ß-TCP) form the part of coatings. Numerous studies have evaluated the crystalline
nature of the implant coatings. The range of percentage was wide about 30% to 66%.
ADVANCES IN SURFACE TREAMENTS OF DENTAL IMPLANTS.
i. BIOMIMETIC CAP COATINGS
The alloys of titanium, alumina and ultra-high molecular weight polyethylene of substrates have
been used in making the biomimetic cap coatings. In this technique a thin layer is formed on the
surface of the implant by mimicking the process of mineralization of bone or tooth. Recent
advances include fluoride phosphate substitution on the titanium dioxide surface, leading to
localized calcium apatite deposition.39
A better cell response of dental implants can be achieved by the use of higher ratio of calcium and
phosphorus along with the addition of silver nanoparticles into the oxide.40
ii. ALBUMIN
Numerous studies have documented that the adsorption of bovine serum albumin (BSA) on
titanium powder has beneficial effect on the release of calcium nd phosphorus from the
coating of the implant. It displays its effect by having not only osteoconductive but also
osteoinductive property.41
iii. BISPHOSPHONATES (BPs) 42,43
In osteoporosis the bisphosphonates like alendronate, pamidronate have shown promising
results. Similar property of reduced bone turnover can be harnessed for better implant
survival.
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iv. ANTIBIOTICS
As in the case of orthopaedic surgeries perioperative antibiotics have documented in
decreased rate of infections. So also in the case of dental implants the antibiotic may be
injected close to the site of implantation. Furthermore co precipitation with biomimetic Ca-P
coating can provide an opportunity to load higher amount of antibiotics.44 Addition of zinc
and fluoride ions have shown to have improved efficacy in preventing infections.45
v. AMELOGENIN46
The amelogenin proteins form an important component of development of extracellular
matrix and thus the enamel. Incorporation into the implant will augment the implant success
rate.
vi. FLUORIDE
The calcification of bone is influenced by fluoride. Studies have revealed the osteopromoting
capacity of fluoride.Bone density and calcification of the bone have improved if fluoride is
available during remodeling process of the bone when incorporated with dental implant.The
rate of osteintegration and firm anchorage of the bone can be achieved with addition of
fluoride. (Roccuzzo and Wilson Jr., 2009).
vii. TETRACYCLINE47
Tetracycline is known for its antimicrobial property. Also recent studies have highlighted its
collagenase inhibiting property leading to increased cell proliferation and bone healing
viii. DISCRETE CRYSTALLINE DEPOSITION (DCD)
In this process the calcium phosphate particles of size 20-100nm are deposited on the surface
of implant. The implants are pre dual acid etched followed by deposition of calcium
phosphate onto the implant surface by sol-gel process named Discrete Crystalline Deposition
(DCD). Ultimately the incidence of infection is markedly reduces as there is reduced bacterial
adhesion. (Smeets et al., 2016).
ix. PHOTO FUNCTIONALIZATION
In this the dental implant is subjected to treatment with ultraviolet light.This treatment brings
about a change in the titanium oxide resulting in enhanced osseointegration, and slows down
age related degradations.
x. EXTRACELLULAR MATRIX PROTEIN COATING
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The extracellular matrix provides crucial guidance for osteoprogenitor cells that migrate to the
implant via interaction of integrins on the cell surface and RGD motifs of fibronectin. Upon
the release of BMP, these cells differentiate into osteoblasts. Studies done on use of
extracellular matrix protein coating have shown to have a positive impact on peri-implant
bone formation.
xi. PEPTIDE COATING
The peptides are biomolecules composed of short sequences of amino acids. Their unique
property facilitates osseointegration as well as inhibit bacterial overgrowth.
xii. BIOACTIVE GLASS COATINGS
The silica-based bioactive glasses have the property of are slowly resorbing synthetic
osteoconductive materials. They form a strong chemical bond with the underlying bone.
Studies by few authors have found implants with bioactive glass coating to have greater
osseointegration as compared to non-coated implants..48.
IV) ADVANCES IN DENTAL IMPLANT MATERIALS
I. TITANIUM IMPLANTS
Since its introduction in 1789 by Wilhelm Gregor titanium has been widely used in
implants. This can be attributed to its property of biocompatibility, ability to form stable
oxide layer. The limiting factor being aesthic concern due to the dark gray appearance of
the metal making way for a tooth colour implant like zirconia 49
II. POLY-ETHER-ETHER-KETONE (PEEK)49
PEEK is a high performance semi-crystalline thermoplastic polymer. The advantage
include very good strength and stiffness with an outstanding thermal and chemical
resistance—e.g., against oils and acids. Also the colourless and elastic modules
nature makes it resemblance to bone.However the limiting factor being disturbed
oseointegration.
III. ZIRCONIA IMPLANTS50
The name of the metal zirconium originates from the Arabic ‘‘zargun’’ (golden in
color), which in turn comes from the two Persian words Zar (gold) and Gun (color).
In 1975, Garvie et al. propose a model to rationalize the good mechanical properties
of Zirconia, by virtue of which it has been called ‘’ceramic steel’’Zirconia proved to
be a superior material of choice as it was inert along with minimum ion release had
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higher fracture resilience and higher flexural strength. Due to its property of better
osseointegration, minimal plaque accululation and better maintenance of soft tissues
and last but not the least aesthetic appeal has made it use widespread in implants.
ZIRCONIA TOUGHENED ALUMINA (ZTA) AND ALUMINA
TOUGHENED ZIRCONIA (AZT)51
These are another class of bioceramics in use for dental implants.. They are called either
Zirconia toughened Alumina (ZTA) when Alumina is the main component (70–95 %), or
Alumina Toughened Zirconia (ATZ), when Zirconia is the main component.The
advantages includes characteristics of Alumina (high hardness, high stiffness) with the
mentioned properties of Zirconia, i.e., the high strength and high toughness, with
improvement of slow crack growth resistance.
POWDER INJECTION MOLDING (PIM)
An alternative to classical machining for preparing Zirconia and other ceramics is the
Powder injection molding (PIM), also called ceramic injection molding (CIM). It is a
combination of injection molding and powder technology mixing, injection molding,
debinding, and sintering. Various methods are available and depend on the pressure used
for molding and injection.51
IV. TANTALUM IMPLANTS52-54
Tantalum with its success in orthopaedic implants has entered into the arena of
dental implants. Its property of being corrosive resistant and better osseointegration
has led to emergence of its use in the implants.
.
PRODUCTION OF POROUS TANTALUM TRABECULAR METAL (PTTM)
The porous tantalum trabecular metal as the name suggests has high volumetric
porosity, high frictional characteristics and low modulus elasticity.
ADVANTAGES OF PTTM-ENHANCED TITANIUM DENTAL IMPLANTS
1) Due to the presence of open-cell dodecahedron repeat structure angiogenesis takes
place resulting in better implant anchorage.
2) Tantalum layer of PTTM, when oxidized, is highly unreactive, and therefore,
biocompatible in the body.
3).Tantalum does not exhibit toxicity to surrounding cells, nor does it inhibit local
cell growth, i.e. osseous in growth of surrounding bone
V. TRANSITIONAL IMPLANTS
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Their diameter ranges from 1.8 to 2.8 mm and length ranges from 7 to 14 mm.
Transitional implant are fabricated with pure titanium in a single body with treated
surface. They play an important role by absorbing the masticatory stress thus aidind
in the healing phase.
COMMERCIALLY AVAILABLE TRANSITIONAL IMPLANT SYSTEM
- Immediate Provisional Implant System –IPI (Nobel Biocare) - Modular
Transitional Implant System -MTI (Dentatus)
-TRN/ TRI Implants (Hi Tec implants)
VI. ONE-PIECE IMPLANTS55
Abutment and implant body are in one piece and not separate.They are commercially
available in 3 mm diameter and 12, 15, and 18 mm length.
(a) Maximum strength – It is one-piece, titanium alloy construction provides
maximum strength, while its 3.0 mm diameter allows placement in areas of
limited tooth-to-tooth spacing.
(b) Minimal surgery – Because one-piece implants are placed using a single-stage
protocol, the soft tissue experiences less trauma than typical two-stage protocols
with maximum esthetics.
VII. TAPERED IMPLANTS & GROOVY IMPLANTS
These implants offer in one body geometry, parallel walled with a diminishing thread
depth toward the apical of the implant and secondary groove underneath each thread
to enhance the initial stability. Cutting flutes incorporated at the apex of the implant
give this implant design self-tapping capability.Dehiscence and fenestration is
reduced.
VIII. SHORT LENGTH IMPLANTS
In patients with reduced alveolar height short implants are preferred as to avoid more
invasive surgical procedure and thus overall hospitalization and cost of treatmemt.
.
IX. MINI IMPLANTS56
As the name suggests these are ultra-small sized titanium screws of diameter 1.8 mm
wide. These are used in cases wherin acceptable and satisfactory function cannot be
achieved with conventional prosthesis. For example, in patients with flabbyridges,
atrophic ridges or in cases with poor availability of residual bone where there is
denture instability or lack of retention, commonly seen in edentulous mandible.
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X. PTERYGOID IMPLANTS
Pterygoid implants have the advantage of allowing anchorage in the posterior
atrophied maxilla, eliminating the need of sinus lifts or bone grafts. In addition
posterior cantilever can be eliminated and axial loading is improved. These implants
can be placed in two different locations such as pterygoid process or in a most
anterior position, the pterygomaxillary process.However, the implant length and
angulations vary between these two locations. Shorter implants are generally placed
in the pterygomaxillary region with angulations of 10–20 to simulate the proper
angulations of the third molar. On the other hand, the longer implants are anchored
to the pterygoid plate of sphenoid bone.
XI. ZYGOMATIC IMPLANTS
In situations like unsuitable condition in posterior maxilla for implant insertion
specific implants like zygomaticus fixture were developed as asolution. There are 8
different lengths, ranging from 30 to 52.5 mm and 45o angulated head to compensate
for the angulation between the zygoma and the maxilla.
XII. LIGAPLANT57
This technology is nothing but combination of the PDL cells with implant
biomaterial. Currently research are going on in making this implant a noble one.
Ligaplants has certain properties like:
1. PDL cells act as a soft, richly vascular, and cellular connective tissue which
permits forces elicited during masticatory function and other contact movements to
be distributed to the alveolar process via alveolar bone proper.
2. It act as a, shock absorber giving the tooth some movement in the socket.
3. It provides Proprioception.
FUTURE TRENDS
Future developments of biomaterial surfaces will include more and more sophisticated and multi (bio)
functional surfaces. (Ratner 1996, Sackmann 1966). The latter include the following aspects: 58
1. An almost revolutionary development is ongoing with regard to the possibilities for building up the
micro-architecture of surfaces. This will be exploited to optimize the 3-D surface architecture, with the
intention of functionally matching different biological entities such as proteins, cell processes and whole
cells. This matching aims at recognition at both the molecular and cell size levels.
2. The micro-architectural functionality mentioned will be combined with corresponding chemical patterns
working in synergy with the micro architecture.
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3. Controlled surface porosity will provide new functions, influencing cell surface interaction, transport of
nutrients, and signal substances, release of functional additives, etc.
4. Programmed dissolution of multilayered surfaces provides new opportunities to optimize the bio material
surface for different periods of the healing phase. Such time programming of the surface can be used to
expose different micro-architectures, different chemical patterns and different porosities at different times.
It also provides opportunity of time-programmed release of different inorganic and organic stimuli, like
growth hormones.
5. By the use of soft, visco-elastic over layers, the mechanical properties of surfaces at the macro and micro
scale can be optimized for the interface. Such over layers may involve bio membranes arid hydrogels.
6. Enhancement of bone-titanium integration profile with UV-photo functionalized titanium- Photo
functionalization describes an ultraviolet light treatment of dental implants taking place immediately before
their placement.
CONCLUSION
Dental Implants are used to support single and multiple unit restorations in the upper and lower jaws. It has
the provision of being placed in the healed bone or the socket of the missing tooth. Also the structure of the
implants makes it possible to place it in a bone irrespective of the height i.e it can be placed in a bone with
less height as well as less width. The implant can be placed with flap or flapless technique. A thorough
understanding of the maxillofacial anatomy is recommended so that bi-cortical engagement is achieved.
The research and development going on these implants have made them a viable option for restoring
atrophied jaws as they don’t require extensive augmentation and allow for immediate loading. They can
also be placed with a flapless technique and can be combined with any implant. Despite of the data
available on their success in treating a variety of cases these implants have gained little trust among
conventional implantologists, it seems further Research and development and more concrete data on
clinical cases are required to prove their efficacy as a replacement to conventional implants.
Hence, truthful efforts to achieve this goal along with a thorough training of the dental professionals to
perform as a team and long-term periodic maintenance by the patients surely will make dental implants the
propitious future of dentistry.
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