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OSSEOINTEGRATIONOSSEOINTEGRATION

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The Amphora

Peter Apelgren

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Contents

Introduction

Historical review

Definition

Bone density classification

Biological considerations for

osseointegration

Bone implant interface

Bone remodeling

Foreign body reaction

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… Bone to implant interface

Mechanism of osseointegration

Ultrastructure in osseointegration

Destruction of osseointegration

Soft tissue implant interface

Peri-implant membrane

Disease activity in peri-implant tissue

Neuromuscular system as it relates to the implant

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….

Factors influencing osseointegration

Osseointegration vs biointegration

Success criteria for osseointegrated implants

Clinical applications of osseointegration

Future of osseointegration

Summary & Conclusion

References

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Introduction

The ideal goal of modern dentistry is to restore the

patient to normal contour, function………..

Implant dentistry is unique because of its ability to

achieve this goal regardless of the stomatognathic

system.

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…..

The primary function of an implant is to act as an

abutment for prosthetic device.

The present surge in the use of implants was

initiated by Branemark (1952)………..

Described the relationship between titanium and

bone for which they coined the term

osseointegration.

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Definition

The word osseointegration consists of “OS” the

Latin word for bone and “integration” derived

from Latin word meaning the state of being

combined into a complete whole.

Osseointegration is defined as a direct bone

anchorage to an implant body which can provide

a foundation to support a prosthesis.

“Direct structural and functional connection

between ordered, living bone and surface of a

load carrying implant”.

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American Academy of Implant Dentistry

defined it as “contact established

without interposition of non bone tissue

between normal remodeled bone and on

implant entailing a sustained transfer

and distribution of load from the

implant to and within bone tissue”.

…..

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Historical Review

The concept of osseointegration was developed and the term was

coined by Dr. Per-Ingvar Branemark,

Professor at the institute for Applied Biotechnology, University of

Goteborg, Sweden.

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Initial concept of osseointegration stemmed

from vital microscopic studies of

microcirculation in bone repair mechanisms.

Titanium chamber was surgically inserted

into the tibia of of a rabbit.

It was considered the best material for

artificial tooth root replacement.

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…..Many studies followed involving titanium

implants being placed into jaws of dogs.

Direct bone anchorage has been shown to

be very strong. A force of over 100kg was

applied to dislodge an implant.

Based on such a consequence the

foundation for Osseo integration and the

Branemark implant system was established

in 1952.

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Studies on humans were

conducted by means of an

implant optical titanium chamber

in a twin pedicle skin tube on the

inside of the left upper arm of

volunteers.

Tissue reactions were studied in

long term experiments.

All this lead to the treatment of

first edentulous patient in 1965.

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History of Branemark system categorized in three stages

Early stage (1965-1968)

Developmental stage (1968-1971)

Production stage (1971 – present)

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Bone density classification (Misch)

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Biological Considerations for Osseointegration

Bone implant interface

When compared to compact bone

spongy bone has less density and

hardness is not a stable base for

primary fixture fixation.

In the mandible the spongy bone

is more dense than maxilla.

With primary fixation in

compact bone, osseointegration

in the maxilla require a longer

healing period.

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Bone remodeling

Osseointegration requires new bone formation

around the fixture. A process resulting from

remodeling within bone tissue.

Osteoblastic and osteoclastic activity helps

maintain blood calcium without change in

quantity of bone.

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…..

To maintain a constant level of bone

remodeling there should be proper local

stimulation, crucial levels of thyroid

hormone, calcitonin and vitamin D.

Occlusion or occlusal force stimulus are

both important to optimal bone remodeling.

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Foreign body reaction

Organization or an antigen antibody

reaction occurs when a foreign body is

present in the body.

This reaction occurs in the presence of a

protein but with implant materials devoid

of proteins no antigen antibody reaction.

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…..

When titanium is used no foreign body reaction are

seen.

The implant material is an important factor for

Osseo integration to occur.

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Bone to implant interface

Two basic theories

Fibro-osseous integration by Linkow, James & Weis

Osseointegration by Branemark

Meffert divided osseointegration

Adaptive osseointegration Biointegration

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American Academy of implant dentistry defined

fibrous integration as tissue to implant contact with

healthy dense collagenous tissue between the

implant and bone.

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…..

The fibers are arranged irregularly, parallel to the

implant body, when forces are applied they are not

transmitted through the fibers.

So no bone remodeling expected in fibro-

integration.

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Ichida & Caputo (1986) used photo-elastic

analysis to study the stress concentration along

the implant threads and sharp edges when a

connective tissue like structure was included in

the analysis.

Even stress distribution was seen when there

was direct contact with a bone like structure.

They concluded that implants with fibro-

osseous integration had a tendency of

increased mobility.

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A direct bone implant interface occurs when an

implant is allowed to heal in bone undisturbed.

Main factors affecting osseointegration include

Implant oxide layer contamination.

Poor temperature control during drilling.

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……

A minimum of 3 month healing in mandible and 6

months in maxilla is necessary before load is

applied.

If osseointegration does not occur or a fibrous

connective tissue forms around the implant

organization process continues.

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Biological process of implant osseointegration

The healing process of implant

system is similar to primary

bone healing.

Titanium dental implants show

three stages of healing.

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…..

OSTEOPHYLLIC STAGE

When a implant is placed into the cancellous marrow

space blood is initially present between implant and

bone.

Only a small amount of bone is in contact with the

implant surface; the rest is exposed to extracellular

fluids.

Generalized inflammatory response to the surgical

insult.

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…..

By the end of first week, inflammatory cells are

responding to foreign antigens.

Vascular ingrowth from the surrounding vital tissues

begins by third day.

A mature vascular network forms by 3 weeks.

Ossification also begins during the first week and the

initial response observed in the migration of osteoblasts

from the trabacular bone which can be due to the

release of BMP’s.

The osteophyllic phase lasts about 1 month.

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OSTEOCONDUCTIVE PHASE

Once they reach the implant, the bone cells spread

along the metal surface laying down osteoid.

Initially this is an immature connective tissue

matrix and bone deposited is a thin layer of woven

bone called foot plate.

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…..

Fibro-cartilaginous callus is eventually

remodeled into bone callus.

This process occurs during the next 3 months

Four months after implant placement the

maximum surface area is covered by bone.

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OSTEOADAPTIVE PHASE

The final phase begins approximately 4 months after

implant placement.

Once loaded implants do not gain or loose bone contact but

the foot plates thicken in response and some reorientation of

the vascular pattern may be seen.

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…..

Grafted bone integrates to a higher degree than the

natural host bone to the implant.

To achieve optimal results an osseointegration period

of 4 months is recommended for implants in graft

bone and 4 to 8 months for implant placed in normal

bone.

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Ultrastructure in osseointegration

Osseointegrated fixtures

under occlusal loads are

surrounded by cortical and

spongy bone.

The cortical bone to fixture

surface interface has

canaliculi participating in

electrolyte transportation

near oxide layer.

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Osseointegration in spongy bone occurs as

bone trabaculae approaches the fixture and

come into intimate contact with oxide layer.

Ground substance forms and fills spaces

between bone trabeculae this fuses with

oxide layer.

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Destruction of Osseointegration

The main contributing factor to bone resorption are

local inflammation from plaque and trauma from

occlusion

Direct action of plaque products induces formation of

osteoclasts.

Plaque products at directly on bone destroying it

through a non cellular mechanism.

Stimulate gingival cells, which release mediators for

osteoclast formation.

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Plaque causes gingival cells to release agents which act as

cofactors in bone resorption and which destroy bone by

direct chemical action without osteoclasts.

Bone resorption can be caused by premature loading.

12 months following fixture insertion vertical bone loss is observed due to traumatic surgical procedure. Vertical bone loss approximately 1 to 1.5 mm in first year

Marginal bone loss is 0.05 to 0.1 mm in first year

These measurements can be used a reference and in a bone loss condition should be evaluated to minimize failure.

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Peri-implant membrane

With the osseointegrated implant

the abutment to fixture junction

corresponds to cementoenamel

junction present in natural

dentition.

Peri-implant membrane is similar

to that present in natural

dentition, consisting of peri-

implant free gingiva.

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….

The sulcular epithelium forms the peri-

implant gingival crevice and junctional

epithelium attaches to the abutment forming

a cuff.

With a tight cuff and filamentous attachment

a membrane is sealed tightly and

functionally to the abutment surface.

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Disease activity in peri-implant tissue

The fibrous connective tissue capsule

formed around an implant generally has low

differentiating capabilities such that it also

has less resistance against bacterial bi-

products and does not respond well to

occlusal stimulation.

An osseointegrated implant has periosteum

directly covering the neck of the fixture.

Which may act as a barrier against

inflammation.

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Although the abutment to junctional epithelium

attachment is not strong, a connective tissue band

is tightly attached to the abutment surface and acts

as resistant barrier.

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The neuromuscular system as it relates to the osseointegrated

implantA fixture site does not have periodontal ligament but

has nerve endings located near the fixture, sensing

pain and temperature.

Patients with osseointegrated implants have a high

threshold and low sensitivity for discriminating

thickness.

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…..

As the periodontal ligament is lost the

fixture remains with reduce amount of

receptors.

Impulses from the fixture sites are

transmitted through motor nucleus of

trigeminal nerve.

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Osseointegration Vs Biointegration

dePutter et al in 1985 observed that there are two

ways of implant anchorage

Mechanical and Bioactive

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Mechanical retention

metallic substrate system such as titanium

or titanium alloy.

The retention is based on undercut forms

such as vents, slots, dimples, screws etc.,

Direct contact between the dioxide layer on

the titanium and bone with no chemical

bonding.

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Bioactive retention

Bioactivity

characteristic of an implant material that allows attachment to

living tissues, whereas a non bioactive material would form a

loosely adherent layer of fibrous tissue at the implant interface

Bioactive retention is achieved with

bioactive materials such as hydroxyapatite

(HA), which bond directly to bone

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Plasma spraying & ion sputter coating

Two techniques used to coat metallic implants with HA.

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Plasma spraying

Involves heating the HA by a plasma flame

at a temperature of approximately 15,000° C

to 20,000°C.

The HA is then propelled onto the implant

body in an inert environment like argon, to a

thickness of 50 to 100 μm.

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Ion-sputter coating

Process by which a thin, dense layer of HA can be

coated onto an implant substrate.

Directing an ion beam at a solid-phase HA block,

Vaporising it to create a plasma and then

recondensing this plasma on the implant.

Bone formation and maturation occurs at a faster

rate in the initial phases on HA coated implants

than on non-coated implants

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Advantages of increased surface roughness of Cp Ti implant

Increased surface area of the implant adjacent to

bone.

Improved cell attachment to the implant surface.

Increased bone present at the implant surface.

Increased biomechanical interactions of the implant

with bone.

Promoted inflammation of the periimplant area.

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Clinical advantages of TPS or HA coatings

Increased surface area

Increased roughness for initial stability

Stronger bone-to- implant interface

Additional advantages of HA over TPS include the

following

Faster healing bone interface

Increased gap healing between bone and HA

Stronger interface than TPS

Less corrosion of metal

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Disadvantages of Coatings

Flaking, cracking, or scaling upon insertion

Increased plaque retention when placed above the

bone.

Increased bacteria adhesion and acts as a nidus for

infection

Complications of treating the failing implants

Increased cost

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Factors influencing Osseointegration

Biomaterial for dental implant

Surface composition and structure

Implant design

Heat

Contamination

Primary stability or initial stability

Bone quality

Epithelial down growth

Loading

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1.Biomaterial for dental implant

Implants must not induce a host immune

response Titanium and certain calcium-

phosphate ceramics are biocompatible

and do not stimulate a foreign body

rejection reaction.

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2. Surface composition and

structure

It is thought that cp Ti owes its ability to form an

osseointegrated interface to the tough and relatively inert

oxide layer, which forms very rapidly on its surface.

This surface has been described as osseoconductive, that

is, conducive to bone formation

Other substrates also have this property and may also

stimulate bone formation, a property known as

osseoinduction

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3. Implant Design

The vast majority of commercially available

implants claiming osseointegration status

are cylindrical in shape.

Their design may be threaded or else lack

similar microscopic retentive/stabilization

aspects

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4. Heat

Heating of bone to a temperature in

excess of 47°C during implant surgery can

result in cell death and denaturation of

collagen.

As a result, osseointegration may not

occur, instead the implant becomes

surrounded by a fibrous capsule and the

shear strength of the implant-host

interface is significantly reduced.

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5. Contamination

Contamination of the implant site by organic and inorganic

debris can prejudice the achievement of osseointegration.

Material such as necrotic tissue, bacteria, chemical reagents

and debris from drills can all be harmful in this respect.

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6. Primary stability or Initial stability

It is known that where an implant fits tightly into its

osteotomy site then osseointegration is more likely to

occur.

This is often referred to as primary stability, and where

an implant body has this attribute when first placed

failure is less probable.

This property is related to the quality of fit of the

implant, its shape, and bone morphology and density.

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7. Bone quality

It is a function of bone density, anatomy and volume, and

has been described using a number of indices.

The classifications of Lekholm & Zarb and of Cawood &

Howell are widely used to describe bone quality and

quantity.

The former relates to the thickness and density of cortical

and Cancellous bone,

and the latter to the amount of bone resorption.

Bone volume does not by itself influence osseointegration,

but is an important determinant of implant placement

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8. Epithelial down growth Early implant designs were often associated with down

growth of oral epithelium, which eventually exteriorized

the device.

When the newer generation of cp Ti devices was

introduced great care was taken to prevent this by

initially covering the implant body with oral mucosa

while osseointegration occurred.

The implant body was then exposed and a superstructure

added, since it was known that the osseointegrated

interface was resistant to epithelial down growth.

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9. Loading schemes Delayed loading: The prosthesis is attached at the

second procedure after a conventional healing

period of 3 to 6 months 8, 23.

Early loading: The prosthesis is attached during a

second procedure, earlier than the conventional

healing period of 3 to 6 months. Time of loading

should be stated in days to weeks 8, 23.

Immediate / Direct loading: The prosthesis is

attached to the implants the same day the implants

are placed.

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Success criteria for Osseo integrated Implants

Durability

Bone loss

Gingival health

Pocket depth

Effect of adjacent teeth

Functions

Esthetics

Presence of infection

Intrusion on the mandibular canal

Patient emotional and psychological attitude

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Revised criteria for implant success

Individual unattached implant is immobile when

tested clinically.

No evidence of peri implant radiolucency is present as

assessed on an undistorted radiograph.

Mean vertical bone loss is less than 0.2 mm after 1st

year of service.

No persistent pain, discomfort or infection.

A success rate of 85% at the end of a 5-year

observation period and 80% at the end of a 10-year

period are minimum levels of success.

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Clinical applications of osseointegration

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…..

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Delicate touch

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Futuristic concepts of Osseointegration

OSSEOPERCEPTION

The interaction between

the osseointegrated

fixture bone tissue,

receptor systems and

nervous system has to be

studied.

“Owing to the nature of osseointegration it is not easy to dissect the system of anchorage from the clinical level down to the molecular level or even the real interface which is still

largely a mystery”

- Branemark

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Summary

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Mechanism of Osseointegration

Blood clot (between fixture & bone)

Clot transformed by phagocytic cell (1st to 3rd day)

Procallus formation (containing fibroblasts & phagocytes)

Procallus becomes dense connective tissue (Differentiation of osteoblasts & fibroblasts)

Callus (Osteoblasts on the fixture)

Fibro cartilagenous callus (between fixture & bone)

Bone callus (Penetrates & matures)

Prosthesis attached to the fixtures stimulating bone remodeling

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It is because of the attention to training, research & clinical studies that osseointegration has now become an accepted part of the treatment regime in many countries

world wide and no longer regarded as the last resort when all else has failed but often as a treatment of choice

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References

Hobo, Ichida, Garcia “Osseointegration and occlusal

rehabilitation” Quintessence Publishing.

Jan Lindhe “Clinical periodontology and implant

dentistry” 4th edition, Blackwell Publishing.

Elaine McClarence “Branemark and the development of

osseointegration” Quintessence publication

Carl E. Misch “Implant dentistry” 2nd edition, Mosby.

Hubertus Spiekermann “Color atlas of dental medicine

implantology” Theime Publishers.

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…..

Charles M.Weis “Principles and practice of implant

dentistry” Mosby.

Charles Babbush “Dental implants the art and

science” W.B. Saunders.

Per Ingvar Branemark “Osseointegration and its

experimental background” JPD 1983 Vol. 50, 399-410.

Hanson, Alberktson “Structural aspects of the

interface between tissue and titanium implants” JPD

1983 vol. 50, 108-113.

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….

T. Alberktson “Osseointegrated dental implants” DCNA Vol.

30, Jan 1986, 151-189.

Richard Palmer “Introduction to dental implants” BDJ, Vol.

187, 1999, 127-132.

Geroge A. Zarb “Osseointegrated dental implants:

Preliminary report on a replication study”. JPD 1983, Vol

50, 271-276.

Bergman “Evaluation of the results of treatment with

osseointegrated implants by the Swedish National Board of

Health and Welfare”. JPD 1983, vol. 50, 114-116.

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Thank you