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1. OSSEOINTEGRATION

2. DEFINITIONS
According to Branemark, Zarb, and Albrektsson (1985)
Osseointegration is the direct structural and functional
connection between ordered, living bone and the surface of a
load–carrying implant.

3. According to Branemark’s histologic point of view: (1985)
Osseointegration is a direct connection between a living
bone and load-carrying endosseous implant at the light
microscopic level

4. According to Glossary of Prosthodontic terms (J Prosthet
Dent 2005; 94: p58)
Osseointegration is defined as
The apparent direct attachment or connection of osseous tissue
to an inert, alloplastic material without intervening connective
tissue
The process and resultant apparent direct connection of an
exogenous material’s surface and the host bone tissues,
without intervening fibrous connective tissue present
The interface between alloplastic materials and bone.

5. According to the American Academy of Implants Dentistry
(1986)
Osseointegration is the contact established without
interposition of non-bone tissue between normal remodeled
bone and an implant entailing a sustained transfer and
distribution of load from the implant to and within the bone
tissue.

6. According to Zarb and Albrektsson (1991)
Osseointegration is a time-dependent healing process
whereby clinically asymptomatic rigid fixation of alloplastic
materials is achieved, and maintained, in bone during
functional loading.

7. BONE HEALING
An injured bone heals by Primary or Secondary
process
Primary bone healing occurs at the fracture site
with a clean break.
In this type of healing there is a well-organized
bone formation with minimal granulation tissue
formation.
Ideal in cases of Implants

8. BONE HEALING
Secondary healing occurs when a large defect or
large fracture site precludes close approximation
of the two sites.
This type of healing is prolonged due to infection
and granulation tissue formation.
This type of healing may result in fibrous tissue
formation, which is undesirable in case of
implants.

10. Bone healing around an inserted
implant
Three phases
1
st
phase – injury phase – starts immediately after insertion of
implant
2
nd
phase – granulation phase – 3-2 weeks after implantation.
Formation of new local connective tissue, new capillaries and
new supporting cells.
3
rd
phase – callus phase – 4-6 weeks after injury – evidence of
new bone formation

12. BONE REMODELING
Osseointegration requires new bone formation around
the fixture, a process resulting from remodeling within
bone tissue.
Remodeling, bone resorption, and apposition helps to
maintain blood calcium levels and does not change the
mass quantity of bone.
In spongy bone, with an abundance of osteoblasts and
osteoclasts available remodeling occurs on the surface
of bone trabeculae.

13. CONDITIONS AFFECTING BONE REPAIR AT
AN IMPLANT SITE: (CELLULAR
BACKGROUND)
In principle, bone may react in three different ways as a
response to the necrosis
1. Fibrous tissue formation may occur.
2. Dead bone may remain as sequester without repair.
3. New bone healing or Osseointegration (bone formation =
bone resorption)

14. Bone repair of the necrotic implant cortex will depend on
the presence of
1. Adequate cells
2. Adequate nutrition to these cells
3. Adequate stimulus for bone repair.

15. THEORIES ON BONE TO IMPLANT
INTERFACE
There are two basic theories regarding the bone-implant
interface.
a)Fibro-osseous integration (Linkow 1970, James 1975, and
Weiss 1986)
b) Osseointegration (supported by Branemark, Zarb, and
Albrektsson 1985)

16. FIBRO-OSSEOUS INTEGRATION
Fibro-osseous integration refers to a presence of
connective tissue between the implant and bone.
In this theory, collagen fibers functions similarly
to Sharpey’s fibers found in natural dentition.
The fibers affect bone remodeling where tension
is created under optimal loading conditions.

17. Failure of fibro-osseous theory
It was felt that the peri-implant membrane gave a cushion
effect and acted as similar to periodontal membrane in natural
dentition.
However, there was no real evidence to suggest that these
fibers functioned in the mode of periodontal ligament. Hence
when in function the forces are not transmitted through the
fibers as seen in natural dentition. Therefore, remodeling was
not expected to occur in fibrous integration.

18. THEORY OF OSSEOINTEGRATION
Meffert et al, (1987) redefined and subdivided the term
osseointegration into
“Adaptive osseointegration” and “Biointegration”.
“Adaptive osseointegration” has osseous tissue approximating
the surface of implant without apparent soft tissue interface at
the light microscopic level.
“Biointegration” is a direct biochemical bone surface
attachment confirmed at the electron microscopic level.

19.  Unlike fibro-osseous integration, osseointegration was able to
distribute vertical and slightly inclined loads more equally in
to surrounding bone.
To obtain a successful osseointegration Branemark and
coworkers proposed numerous factors. According to the
proponents the oxide layer should not be contaminated or else
inflammatory reaction follows resulting in granulation tissue
formation.

20. The temperature during drilling should be controlled by
copious irrigation, if not can inhibit alkaline calcium synthesis
there by preventing osseointegration.
 The first month after fixture insertion is the critical time
period for initial healing period. When loads are applied to the
fixture during this period primary fixation is destroyed.

21. MECHANISM OF OSSEOINTEGRATION
(BONE TISSUE RESPONSE)
MECHANISM OF INTEGRATION: (Davies - 1998)
MECHANISM OF INTEGRATION: (Osborn and Newesley –
1980)

22. MECHANISM OF INTEGRATION: (Osborn
and Newesley – 1980)
The terms “Distance and Contact osteogenesis” were first
described by Osborn and Newesley in 1980 and it refers to
the relationship between forming bone and the surface of an
implanted material.
 Distance osteogenesis:
- New bone is formed on the surface of implant in the
peri-implant site
- The existent bone surfaces provide a population of
osteogenic cells that lay down new matrix, which as
osteogenesis continues, encroaches on the implant itself

23. Thus, an essential observation here is that new bone is not
forming on the implant itself, but rather that the implant
becomes surrounded by bone.
In these circumstances, the implant surface will always be
partially obscured from bone by intervening cells and general
connective tissue extra-cellular matrix which makes bone
bonding impossible to achieve

24. Contact osteogenesis
In contact osteogenesis, new bone forms first on the implant
surface
The implant surface must become colonized by a population
of osteogenic cells before initiation of bone matrix formation.
This occurs at remodeling sites where an old bone surface is
populated with osteogenic cells before new bone can be laid
down. These osteogenic cells migrate to the implant surface.

25. MECHANISM OF INTEGRATION: (Davies -
1998)

Davies divided the contact osteogenesis into two distinct early
phases of osteogenic cell migration
 Osteoconduction
 De novo bone formation

26. Osteoconduction:
The term “Osteoconduction” refers to the migration of
differentiating osteogenic cells to the proposed site.
These cells are derived at bone remodeling sites from
undifferentiated peri-vascular connective tissue cells.
A more complex environment characterizes the peri-implant
healing site since this will be occupied transiently by blood.
Migration of the connective tissue cells will occur through the
fibrin that forms during clot resolution
Fibrin, the reaction product of thrombin and fibrinogen
released into the healing site can be expected to adhere to
almost all surfaces. It is via this that the osteogenic cells get
migrated.

27. De novo bone formation
Prerequisite of de novo bone formation - Recruitment of potentially
osteogenic cells to the site of future matrix formation. Differentiating
osteogenic cells, which reach the implant surface initially, secrete a
collagen-free organic matrix that provides nucleation sites for calcium
phosphate mineralization
Two noncollagenous bone proteins Osteopontin and bone Sialoprotein has
been identified in this initial organic phase, but no collagen.
Calcium phosphate crystal growth follows nucleation, and concomitant
with crystal growth at the developing interface, there will be initiation of
collagen fiber assembly

28. Finally, calcification of the collagen compartment will
occur both in association with individual collagen fibers or
in the interfiber compartment. Thus, in this process of de
novo bone formation, the collagen compartment of bone
will be separated from the underlying substratum by a
collagen-free calcified tissue layer containing non-
collagenous bone proteins.

29. STAGES OF OSSEOINTEGRATION
According to Misch there are two stages in osseointegration,
each stage been again divided into two substages. They are:
Surface modeling
Stage 1: Woven callus (0-6 weeks)
Stage 2: Lamellar compaction (6-18 weeks)
Remodeling, Maturation
Stage 3: Interface remodeling (6-18 weeks)
Stage 4: Compacta maturation (18-54 weeks)

30. STAGE 1: (Woven callus)
This stage undergoes from 0-6 weeks of implantation.
Woven bone is formed at implant site. It is often considered as
a primitive type of bone tissue and characterized by
- a random felt-like orientation of collagen fibrils, - numerous
irregularly shaped osteosites and
- relatively low mineral density
It grows by forming a scaffold of rod and plates and thus is
able to spread out in to the surrounding tissue at a relatively
rapid rate.

31. It starts growing from the surrounding bone
towards the implant except in narrow gaps, where
it is simultaneously deposited upon the implant
surface.
Woven bone formation clearly dominates the
scene within the first four to six weeks after
surgery.

32. STAGE 2: (Lamellar compaction)
Starts from 6th week of implantation and continues till 18th
week.
The woven callus matures as it is replaced by lamellar bone.
This stage helps in achieving sufficient strength for loading.

33. STAGE 3: (Interface remodeling)
This stage begins at the same time when woven callus is completing
lamellar compaction.
 The callus starts to resorb, and remodeling of devitalized interface begins.
The interface remodeling helps in establishing a viable interface between
the implant and original bone.
Remodeling of non-vital interface is achieved by cutting/filling cones
emanating from the endosteal surface.

34. STAGE 4: (Compacta maturation)
 18th week of implantation and continues till the 54th week.
Compacta matures by series of modeling and remodeling
processes. The callus volume is decreased and interface
remodeling continues.

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