Osseointegration Flashcards
(40 cards)
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
Why do we use titanium and titanium alloys for implants?
- Low weight high strength/weight ratio
- Low modulus of elasticity,
- Excellent corrosion resistance
- Excellent biocompatibility
- Easy shaping and finishing.
What is the most frequently used titanium alloy and what is its 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
What is another option for implant material if patient doesn’t like metal or titanium?
zirconia
Surface topography influences…
osteoblasts morphology
What surface topography is best for osetoblast morphology: smooth, moderately rough, or rough?
the middle option (moderately rough)
Smooth
Minimally Rough
Moderately Rough
Rough
Smooth: (Sa<0.5μm)
Minimally Rough: (Sa 0.5-1 μm)
Moderately Rough: (Sa 1-2μm) ** ideal
Rough: (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 __________ level.
micrometre
What does surface modifications involve?
- Changing the surface topography using PHYSICAL AND/OR CHEMICAL methods
- Transforming surface properties by COATING with a highly biocompatible material
- Or a COMBINATION of both
What are examples of Surface Modifications?
- 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
Which 2 surface modifications do we use at UMKC most often?
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
What is the bone chemical composition?
Inorganic (65-70%)
Organic (30-35%)
What is the inorganic part of bone (65-70%)?
Crystalline salts (primarily, hydroxyapatite)
What is the organic part of bone (30-35%)?
- Type I collagen (90-95%)
- Non-collagenous proteins
- Proteoglycans
- Growth factors
What are the different cells in bone?
- pre-osteoblast
- osteoblast (creates bone)
- osteocyte (communication through bone)
- osteoclast (break down bone)
- endothelial cell
- monocyte
- macrophages
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
- 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 it 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
Events leading to: Formation of osseointegration encompassed…
coagulum, granulation tissue, development of a provisional matrix, woven bone, parallel-fibered bone and eventually lamellar bone.
Osseointegration : Early Events
2 HOURS AFTER IMPLANT INSTALLATION (in animal)
- Threads are in contact with bone - Mechanical anchorage
- Primary mechanical Stability
- The void between the pitch and the body of the implant: wound chamber
- Blood clot characterized by : erythrocytes, neutrophils and monocytes/macrophages in a network of fibrin + leukocytes engaged in the wound cleaning process
- Blood clot replaced with primitive granulation tissue 4 days after: this tissue contained mesenchymal cells, matrix components and newly formed vascular structures
- Provisional CT matrix had been established