Intro to implants Flashcards
What are the typical problems with fixed/removable prosethetics?
Retention/resistance
Phonetics
Aesthetics
Stability
Micro leakage
Caries in abutments
Lateral forces
Deterioration of peridontal health around abutments
Psychological
How did dental implants change from when they were first invented until now?
First looked at in the 1950s initially made of cobalt chrome and stainless steel which sint’ very biocompatible.
Subperiosteal implants developed next. Initially very stable but lead to infections.
in 1960s and 70s Titanium was found to be very compatible with bone. Classical 2 stage surgery; first stage is placement second stage is uncovering
Andre Schroeder found a method of sectioning the bone and the titanium
What are the benefits of using dental implants?
Implant dentistry revolutionised dental treatment for patients
High survival and success rates
Conservative treatment option
Long term risk benefits were found to be in favour of dental implant use in 1978
What are the primary functions of bone?
Structural support
Calcium metabolism
What are the types of bone?
Compact bone
Spongy bone
Cancellous bone
Cortical bone
Woven bone
Lamellar bone
Bundle bone (only found around the alveolus)
What kind of bone is needed for implants?
A healthy ratio of cancellous bone to cortical bone.
Why is bone important as a calcium reservoir?
Calcium is important for maintaining pH, Nerve and muscle conduction, and heart function are all influenced by calcium levels.
What are the components of the bone’s molecular structure?
Organic bone consists of Type 1 collagen, GAG (glue), PG, Non-collagen proteins, Osteo collagen fibres, and H2O
Inorganic bone consists of hydroxyappatite, calcium carbonate, and fluoride
How much of bone is organic and how much is inorganic?
Organic = 35% Inorganic = 65%
Where do osteoblasts and osteoclasts arise from?
Osteoblasts = bone marrow derived mesenchymal progenitors (endosteal/periosteal origin)
Osteoclasts = bone marrow-derived haematopoietic progenitors
What kind of cytoplasm do osteoblasts have?
Basophilic cytoplasm
What are the functions of osteoblasts?
Bone building cells
Deposit bone matrix
Lay down bone in concentric circles
Phospholipid and proteo-glycan synthesis
Osteogenic cells
What growth factors and cytokines act on on osteoblasts to stimulate their function?
TGF-beta
BMP
PDGF
Insulin-like growth factor
What is an osteocyte?
Most abundant bone cell
Formed as embedded osteoblasts
Express TGF-beta
Communicate via dendrites
What is the function of osteoclasts?
Bone resorption cells
Occupy 1% of bone surfaces
Work in combination with osteoblasts and remain active for 3 weeks.
Tunnels 0.2 - 1mm deep formed by them
Ruffled border contacting the bone, villi at resorption contact and then they digest the bone via proteolytic digestion and phagocytosis
What do osteoclasts look like on microscope?
Multinucleate
Monocyte family
Have vili like projections that are important for bone resorption
Found in howship lacunae
What regulates osteoclast function?
PTH
How do osteoclasts get deactivated?
Typically degenerate via apoptosis
What is the bone matrix made up of?
Collagen fibers that are impregnated with mineral salts.
Mineral salts consist of 85% calcium phosphate, 10% calcium carbonate, 5% calcium fluoride and magnesium fluoride
Non-collagen proteins such as Bone Morphogenic Proteins
What are the types of bone morphogenic proteins?
Growth factors/cytokines
TGF beta superfamily
Bone inducing cytokines BMP2, BMP7
Acid insoluble protein which bind to UD-MesenchymalCSC to get OsteoBlast differentiation
How much resorption happens daily?
Approximately 0.7% of the skeleton is resorbed daily
Where is periosteum located?
Outer surface of most bone but not articular surfaces.
What are the layers of the periosteum?
Outer fibrous layer
Inner cellular layer
Cells and blood vessels are related to the periosteum. What is the significance of this in dentistry?
Raising a mucoperiosteal flap typically causes 0.5mm bone loss.
What dental procedures cause bone modelling?
Orthodontic movement
Implant placement
Sculpting and shaping after growth
What happens during bone remodelling?
It is a cyclical process
No change occurs to the shape of the bone
Old bone is removed and new bone replaced it
How does bone mass change in response to age?
Maxilla grows approximately 10 years after linear growth has finished
Bone mass declines after 4th decade
By 80 years bone mass is 50% less
Women lose more bone mass
How do edentulous ridges differ between upper and lower jaw?
Upper jaw bone tends to be more trabecular.
Upper jaw tends to resorb quicker than lower jaw
Lower jaw bone tends to be more compact and dense
What is osseointegration?
Direct connection between the bone and implant without interposed soft tissue.
What factors are needed for successful osseointegration?
Design
Implant surface condition
Host bed status
Surgical technique
Loading
What are the types of bone quality?
Quality 1: Very hard, very dense, may overheat, anterior mandible
Quality 2: Externally hard, Good core, Ideal for implants, and found in the premolar region
Quality 3: Thin externally, Good core, Good for implants, Maxillary incisor region
Quality 4: Very soft, very thin, found in posterior maxilla
What does quality 1 bone consist of?
Homogenous compact bone
What does quality 2 bone consist of?
Thick layer of compact bone around core of dense trabecular bone.
What does quality 3 bone consist of?
Thin layer of cortical bone around dense trabecular bone.
What does quality 4 bone consist of?
Thin layer of cortical bone around low density trabecular bone
What are the types of implants?
Straight/tapered
One piece/ Two piece
TAD- Orthodontics
What are the microscopically different implants?
V thread
Reverse thread
Square thread
What is the ideal size of microscopic implant?
100 microns for complete bone ingrowth
What are the types of implant surfaces?
TItanium machined surfaces
Titanium plasma spray surface (using plasma spray to spray titanium particles on top of the implant (good for increased surface area but has a tendancy to break off the implant surface)
Sand blasted surface
Hydroxyl apatite coated titanium surfaces
How is the implant surface designed?
Coating is designed to decrease time for osseointegration
Machine surface/sand blasting/acid etching
Surfaces can add/subtract
They can affect the cytokine expression and growth factors in the bone
What kind of surface treatments are supported by evidence in literature?
Current literature supports subtractive surface treatments:
Acid etching is beneficial
Sandblasting large grit
Additive surface treatments can breakdown and are unstable
What are the stages of osseointegration?
Osteophillic
Osteoconductive
Osteoadaptive
What happens in the osteophillic stage of osseointegration of implants?
Occurs upon insertion
Body responds to the rough surface
Clot formation occurs and cytokines are released
Vascular growth
When does osteointegration begin to occur during the osteophillic phase?
Starts 1 week and lasts for a month
What happens during the osteoconductive phase?
Bone cells spread along titanium and a thin layer of woven bone is formed. Bone is gradually added during this stage over 3 months until it reaches stability.
What happens during the osteopadaptive phase?
Starts at 3 - 4 months
Remodelling occurs around the implant
Initial Bone to Implant Contact thickens and implants stable under the load.
What are the types of stability of newly integrated implants?
Primary stability as the bone remodels
Secondary stabliity when the de novo bone forms around the implant
