Osseointegration Flashcards
6 Key Factors For Successful Implant Osseointegration
- Biocompatibility of the Implant material
- Macroscopic and microscopic nature of the implant surface
- The status of the implant bed in both a health (non-infected)
and a morphologic (bone quality) context - The surgical technique
- The undisturbed healing phase
- The subsequent prosthetic design and long term loading phase
CP (Commercially Pure) Titanium and Titanium Alloys
(5)
- Low weight high strength/weight ratio
- Low modulus of elasticity,
- Excellent corrosion resistance
- Excellent biocompatibility
- Easy shaping and finishing.
The most frequently used alloy and composition
(titanium.6 aluminum-4 vanadium) :
- 90% titanium,
- 6% aluminum (decreases the specific weight and improves the elastic
modulus)
- 4% vanadium (decreases thermal conductivity and increases the
hardness).
TITANIUM OXYDE LAYER:
tenacious oxides in air or oxygenated
solutions - Promotes adhesion of osteogenic cells
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How about Zirconia?
In vivo, Prospective, RCT
- Early colonization on zirconium oxide VS titanium alloy
abutments - 22 Pts , 2 implants per Pt
- Bacteria Sampling, PD, BOP
- Bacterial counts of 7 bacterial species 2 weeks and 3 months
following abutment connection. - No differences in any parameter
Surface topography influences
osteoblasts morphology
Smooth
Minimally Rough
Moderately Rough
Rough
(Sa<0.5μm)
(Sa 0.5-1 μm)
(Sa 1-2μm) ** ideal
(Sa>2 μm)
Smooth and minimally rough surfaces showed
Moderately rough surfaces showed
less strong bone responses than rougher surfaces.
stronger bone responses than rough in some studies.
Surface topography influences
bone response at the micrometre level.
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LIMITATIONS
varying quality of surface evaluations : a surface termed ‘rough’ in one study was not uncommonly referred to as ‘smooth’ in another; many
investigators falsely assumed that surface preparation per se identified the roughness of the implant; and many other studies used only
qualitative techniques such as SEM.
Furthermore, filtering techniques differed or only height parameters (Sa, Ra) were reported.
Surface Modifications
(3)
- Changing the surface topography using
PHYSICAL AND/OR CHEMICAL methods; - Transforming surface properties by COATING
with a highly biocompatible material (e.g.
calcium phosphate and functional peptide) - COMBINATION
Surface Modifications
Which 2 do we use at UMKC most often?
- Machined
- Plasma-spray or Titanium spray
- Sandblasted
- Sandblasted and acid-etched
- RBM (Resorbable Blast Media, with Calcium Phosphate)
- Zirconia ceramic
- Hydroxyapatite Coatings
- Lasers
- Nano-structured surfaces
ACID ETCH
PLASMA SPRAY
A greater surface roughness
increases the potential for
biomechanical interlocking
Rougher implants surfaces have an higher percentage
of
bone implant contact and also an higher torque
removal than machined surfaces.
Bone Biology- Chemical Composition
Inorganic (65-70%)
Organic (30-35%)
Inorganic (65-70%)
Crystalline salts (primarily, hydroxyapatite)
Organic (30-35%)
- Type I collagen (90-95%)
- Non-collagenous proteins
- Proteoglycans
- Growth factors
3 Davis’ basic concepts
First, bone matrix is synthesized by only one cell: the osteoblast.
Second, as a result of the polarized synthetic (meaning the
synthesis of bone matrix) activity of osteoblasts, bone
grows only by apposition.
Third, bone matrix mineralizes and has no inherent capacity
to “grow.”
Distance Osteogenesis
- de novo bone formation occurs on the surfaces of old
bone in the peri-implant site. - The bone surfaces provide a population of osteogenic
cells that lay down a new matrix that encroaches on the
implant. - New bone is not forming on the implant, but the latter
does become surrounded by bone. - Results in bone approximating the implant
Contact Osteogenesis
No bone is present on the surface of the implant upon
implantation
New bone forms first on the implant surface Implant surface
has to become colonized by bone cells before bone matrix
formation can begin
Bone is formed for the first time at the appropriate site by
differentiating osteogenic cells.
surface.
* Results in bone apposition to the implant surface
Temporal sequence of healing
-THE ANIMAL MODEL
AIM: Temporal sequence of healing of osseointegration
Dog Model - Histology from 2h to 12 weeks after installation
Events leading to : Formation of osseointegration encompassed
coagulum, granulation tissue, development of a provisional matrix, woven bone, parallel-fibered bone and eventually lamellar bone.
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Osseointegration : Early Events
2 HOURS AFTER IMPLANT INSTALLATION
- Threads are in contact with bone - Mechanical anchorage
- Primary mechanical Stability
- The void between the pitch and the body of the implant: a well
defined wound chamber - Blood clot characterized by : erythrocytes, neutrophils and
monocytes/macrophages in a network of fibrin + leukocytes
engaged in the wound cleaning process - Blood cloth replaced with primitive granulation tissue 4 days
after : this tissue contained mesenchymal cells, matrix
components and newly formed vascular structures (i.e evidence
of angiogenesis) - Provisional CT matrix had been established
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Osseointegration : Early Events
4 DAYS
ROUGH : In the proximal region an early granulation
tissue has formed, whilst in the region close to the
device, large numbers of erythrocytes remain
MACHINED: In the area close to the parent bone the
clot has been penetrated by vascular structures
surrounded by fibroblast-like cells, whereas in the area
close to the surface of the device, large numbers of
erythrocytes, polymorphonuclear leukocytes and
macrophages remain.
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Osseointegration : Bone Modeling -
at 1 week
- Provisional CT in the wound chambers rich in vascular structures and mesenchymal cells.
- A relatively small number of inflammatory cells was still present.
- A cell-rich immature bone (i.e. woven bone) was seen in the provisional CT that surrounded the blood vessels.
- Woven bone formation occurred in the center of the chamber as well as in discrete locations that apparently were in direct contact with the surface of the titanium device : “Contact Osteogenesis”
- Contact osteogenesis was not observed on polished implant surfaces at this stage
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Osseointegration : Bone Modeling -
at 2 weeks
- Woven bone formation was more pronounced in all compartment
- Woven bone were noticed in the bone marrow regions ‘apical’ of the implant. This osteogenesis took place at a distance from the implant surface and hence was termed ‘distant osteogenesis’.
- In many regions woven bone was bridging to the surface of the implant.
- At this time point of healing, most of the implant surface was occupied by newly formed bone, which formed a continuous coat on the implant surface (i.e. ‘osteocoating’).
- Osteoclast formation noticed on the pristine bone surfaces, resulting in bone resorption adjacent to the implant surface, especially in areas of pressure of the implant to the bony bed (i.e. pitches of the threads).
- After 2 weeks of healing: Mechanical stability replaced by Biological bonding and stability.
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Osseointegration : Bone Modeling -
at 4 weeks
- Continuous cell-rich ‘osteocoating’ covered most of the titanium wall of the chamber.
- The central portion of the chamber was filled with a primary spongiosa, rich in vascular structures and contains a multitude of mesenchymal cells.
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Osseointegration : Bone reModeling -
From 6 to 12 weeks
- Most of the wound chambers were now filled with mineralized bone.
- Bone tissue consisted of primary and secondary osteons
- Mature bone tissue contact with the implant surface to a very high extent.
- Bone marrow containing blood vessels, adipocytes and mesenchymal cells was observed to surround the trabeculae of mineralized bone.
- The bone trabeculae had become reinforced by lamellar or parallel-fiber bone deposition, thus providing a structure to cope with the bearing of load.
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Temporal sequence of healing
-THE HUMAN MODEL
- Healing period of 6 weeks (7, 16, 27, 31)
- Implants manufactured by the Institut Straumann AG (Basel,
Switzerland), with either a hydrophobic SLA” or a chemically
modified hydrophilic SLActive”
Loading
* The original Branemark’s protocol recommended strict adherence to surgical and prosthodonrc
technique:
- “Non-disturbed” healing period of 3-6 months
- Ater this healing period, an abutment and suprastructure
prosthesis are fabricated and auached to an implant fixture.
Today clinicians have 3 loading oprons:
Immediate loading – prosthesis connected to the implant fixture within the first 48hrs.
Early loading – prosthesis is connected to the implant fixture ater the first 48hrs but prior to 3 months.
Delayed loading – prosthesis connected to the implant fixture ater the iniral 3 months.
Immediate Loading vs Conventional Loading
CONCLUSIONS:
Immediate loading may impose a greater risk for implant failure when compared to conventional loading, although
the survival rates were high for both groups.
Is bone matrix organization influenced by loading?
IL and NL implants showed
the same degree of osseointegration. The bone matrix around IL implants had a higher
quantity of transverse collagen fibers and presented a higher level of mineralization.
Dental implants placed in function change the
microstructure of the bone increasing the content of
collagen fibers transversally oriented when compared to the residual alveolar bone after tooth
extraction. The orientation of collagen fibers was strictly dependent on the shape of the implant.
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Results at 4 weeks
Submerged Implant
- The peri-implant bone was very
trabecular - Many marrow spaces were
present. Only few 100-200 μm
bone trabeculae were found
directly on the implant surface in
the middle and apical portions of
the implant.
BIC 54.7 ± 4.2 %
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Results at 4 weeks
IL Implant
- Compact, cortical, lamellar bone was
present around the implant. Dense
CT, with only a few inflammatory
cells, was observed at the level of the
shoulder of the implant and of the
peri-implant coronal portion. - Some newly-formed bone trabeculae
were present, on the implant surface,
in the coronal area. - Wide osteocyte lacunae were present
in these trabeculae. - Newly-formed, strongly stained bone
surrounded the pre-existing cortical
bone.
BIC 65.6 ± 3.9 %
Bone Healing after different site preparation
techniques
Osteotomy can be prepared using sequential drilling, blunt osteotome,
or piezosurgery:
- Sequential drilling —> free osseous debris and microfractured walls —> additional biological
energy to repair + resorbed delaying bone modeling contact to the implant. - Similarly, blunt osteotome technique leaves loose osseous particles.
- Piezosurgery leaves a cleaner cavity for implant placement, with very few osseous debris.
he insertion torque can be defined as the measurement of the
ideally=
resistance that the
implant encounters during its advancement in the apical direction by means of a
rotating movement on its axis
> 35 ncm
Piezosurgery was more beneficial to use for
implant site preparation.
INSERTION TORQUE
Is there an optimal insertion torque for osseointegration to occur
around unloaded implants?
CONCLUSION:
no significant differences were observed in the way bone
heals around implants placed at high vs. low inser>on torque.
