osseointegration Flashcards
6 Key Factors For Successful Implantn Osseointegration
1. Biocompatibility?
2. implant surface?
3. The status of the implant bed?
4. technique?
5. healing?
6. design/loading?
- 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
properties of Ti making it good for implants
- Low weight high strength/weight ratio
- Low modulus of elasticity,
- Excellent corrosion resistance
- Excellent biocompatibility
- Easy shaping and finishing.
Most frequent Ti alloy
properties of parts
The most frequently used alloy (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).
Ti oxide layer
made with tenacious oxides in air or oxygenated solutions: this will promote adhesion of osteogenic cells
what other material may be used for implants
zirconia, similar to Ti but not a substitute
surface topography of implants can influence what?
osteoblast morphology and bone response at the micrometre level.
what type of surface has the best incorporation of osteoblasts
moderately rough (Sa-1 to 2 micrometers)
moderately rough surfaces have highest values for?
Histomorphometry: bone-to-implant contact
* Removal torque analyses
* pushout/pullout tests
surface modifications
- 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
Potential Surface Modifications
- Machined- smoothed
- Plasma-spray or Titanium spray- increase irregularities (SA)
- Sandblasted- SA
- Sandblasted and acid-etched-SA
- RBM (Resorbable Blast Media, with Calcium Phosphate)
- Zirconia ceramic
- Hydroxyapatite Coatings
- Lasers
- Nano-structured surfaces
Mechanical Considerations
A greater surface roughness increases the potential for biomechanical interlocking
Rougher implants surfaces have an higher percentage of bone implant contact and also a higher torque removal than machined surfaces.
Bone Biology- Chemical Composition
Inorganic (65-70%)
-Crystalline salts (primarily, hydroxyapatite)
Organic (30-35%)
- Type I collagen (90-95%)
- Non-collagenous proteins
- Proteoglycans
- Growth factors
cells of bone/ lineages
preosteoblasts>osteoblasts>osteocytes
monocytes> macro> osteoclasts
where are osteocytes? can they comm?
lacunae, possess dendrites for communication
osteoblast bone deposition
produce non mineralized osteoid that then mineralizes to newly formed bone and will then form mature bone
3 Davis’ basic concepts of bone
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
would occur with smooth implants, bone froms towards the implant from socket walls
* 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
with our rough surfaces, progenitor cells will colonize and form bone around implant
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.
Results in bone apposition to the implant surface
contact vs distant osteogenesis
with contact: bone forms at surface and can occur more rapidly
2 HOURS AFTER IMPLANT INSTALLATION HISTO
* Threads are in contact with?
* Primary what Stability?
* The void between the pitch and the body of the implant?
* Blood clot characterized by?
* Blood cloth replaced with? when? contains?
* Provisional CT matrix?
- 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
4 DAYS implant histo of rough surface
ROUGH : In the proximal region an early granulation tissue has formed, whilst in the region close to the device, large numbers of erythrocytes remain
4 days histo with machined surface
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, PMN and macrophages remain.
Osseointegration : Bone Modeling -
at 1 week
* Provisional CT?
* inflammatory cells was present?
* what surrounded the blood vessels?
* Woven bone formation?
* what was not observed on polished implant surfaces at this stage?
- 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
Osseointegration : Bone Modeling -
at 2 weeks
* Woven bone formation?
* Apical Woven bone?
* In many regions woven bone was?
* At this time point of healing, most of the implant surface was occupied by?
* Osteoclast formation?
* After 2 weeks of healing: Mechanical stability replaced by?
- 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.
Osseointegration : Bone Modeling -
at 4 weeks
* ‘osteocoating’?
* The central portion of the chamber was filled with?
- 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.
Osseointegration : Bone reModeling -
From 6 to 12 weeks
Most of the wound chambers were now filled with?
* Bone tissue consisted of?
* Mature bone tissue contact with the implant surface?
* what surrounds the trabeculae of mineralized bone?
* The bone trabeculae had become reinforced by?
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.
The original Branemark’s protocol for loading
- The original Branemark’s protocol recommended strict adherence to surgical and prosthodontic 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.
**- now we only wait 3 months **
loading options in modern practice
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
Immediate loading may impose a greater risk for implant failure when compared to conventional loading, although the survival rates were high for both groups.
**only immeadiately load with correct cases **
good cases for immeadiate loading, why?
when there are multiple implants placed and connected to one another (over-denture)
By connecting the implants with the acrylic restoration, we limit the micro-movements and therefore, ensuring the osseointegration process
Ideal insertion torque for immediate loading ?
Ideal insertion torque for immediate loading ? >35Ncm
Prosthesis Conversion with immeadiate loading
convert a denture to a fixed overdenture at same appt as implant placement, this will be temporary restoration
Is bone matrix organization influenced by loading (IL vs NL)
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.
NL vs IL and collagen fibers
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.
submerged implants bone 4 weeks
- 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 %
IL implants bone at 4 weeks
- 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 %
submerged implant bone at 8 weeks
- Bone trabeculae with many wide marrow spaces and many capillaries were present in the peri-implant tissues, but few marrow spaces abutted directly on the implant surface.
- Mineralized tissue was present at the interface with the implant surface.
- No gaps or connective, fibrous tissues were present at the bone-implant interface.
- The bone near the implant appeared to be more mature than that found at a distance.
BIC 62.3 ± 4.9 %
IL bone at 8 weeks
- At low-power magnification mature,
trabecular bone, with many wide
marrow spaces with a large number of
capillaries, was present around the
implant perimeter. - A large portion of the implant surface
appeared to be lined by bone trabeculae. - CT with few inflammatory cells, was
present on one side of the implant, in
the coronal portion. - At the bottom of this pocket there
was newly formed bone. - No osteoclasts were observed in the
area of the pocket
submerged vs IL 4-8 weeks compared
CONCLUSIONS: Very high BIC percentages were present, after 4 and 8 weeks, both around the submerged and IL implants. An higher quantity of bone was present around the IL implants, but due to the small number of specimens it was not possible to do any statistical evaluation. IL did not seem to impede bone formation in the early healing periods.
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.
Piezosurgery was more beneficial to use for implant site preparation.
insertion torque
The insertion torque can be defined as the measurement of the resistance that the
implant encounters during its advancement in the apical direction by means of a
rotating movement on its axis
Low R=low torque (cancellous bone)
Is there an optimal insertion torque for osseointegration to occur around unloaded implants?
: no significant differences were observed in the way bone heals around implants placed at high vs. low insertion torque.
