Osseointegration Flashcards

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1
Q

Define osseointegration:

A

A process whereby clinical asymptomatic rigid fixation of alloplastic materials is achieved and maintained in bone during functional loading

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2
Q

How long does a treatment plan usually suggest an implant is left unloaded for?

A

3-6 months

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3
Q

What is primary stability?

A

What is achieved immediately by mechanical fixation (i.e. screwed into a surgically created hole?

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4
Q

Why is primary stability paramount for clinical success?

A

If its moving it won’t heal properly and therefore will be unable to resist forces on tooth in all directions

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5
Q

Which 4 factors influence the degree of primary stability achieved?

A
  • Bone quality and quantity
  • Implant design
  • Patient factors
  • Surgical technique
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6
Q

What are the two main factors for failure of an implant?

A

Mobility and pain

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7
Q

What is secondary stability?

A

Osseointegration

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8
Q

What does the presence of fibrous tissue between the implant and bone mean for the future of the implant?

A

It will fail -> mobility

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9
Q

What happens in osseointegration?

A

Direct contact between implant and bone (histologically osteoblasts and mineralised matrix contact the implant surface)

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10
Q

Describe the healing process of implants:

A

Highly dynamic, continuous process = maintenance of peri-implant bone and depends on both bone modelling and remodelling

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11
Q

What happens when load is applied to an implant?

A

Amount of contact between bone and implant increases (needs forces to maintain)

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12
Q

What is the abutment important for?

A

Soft tissue attachment (blocks pathway for infection = peri-implantitis -> bone resorption)

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13
Q

What are the 3 phases of endosseous wound healing (within the bone)?

A
  • Osteoconduction
  • De novo bone formation
  • Bone remodelling
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14
Q

What is distance osteogenesis?

A

Bone formation on the old bone (distant from the implant)

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15
Q

What is contact osteogenesis?

A

Bone formation on the implant

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16
Q

How is contact osteogenesis encouraged?

A

Surface of implant treated -> aimed to attract by osteoconduction of cells = more favourable for secondary stability

17
Q

What is the process of osteogenesis?

A

Activated platelets release a number of growth factors = mitogenic for fibroblasts and osteoblasts, chemotactic for fibroblasts, neutrophils and osteogenic cells

18
Q

What is mitogenic?

A

Encourages cells to divide

19
Q

What is chemotactic?

A

Attracts cells

20
Q

Why is implant surface important?

A

Potentially modulates level of platelet induction and/or maintains anchorage of fibrin scaffold along which cells must migrate

21
Q

What % implant surface is integrated to be deemed successful?

A

60-70% of implant

22
Q

What % of bone implant contact (BIC) did albresktsson find in his study of implants in the maxilla and the mandible?

A

Maxilla = >50%, mandible = >75%

n.b. clinical relevance of this is unknown

23
Q

What % of bone implant contact (BIC) did albresktsson find in his study of implants between loaded and unloaded implants?

A

10% less in unloaded

24
Q

What is visible when looking at an osteointegrated implant under an electron microscope?

A

A 20-500nm thick layer of dense amorphous substance between bone and implant (organic bone matrix origin, probably proteoglycans an possible osteopontin and bone sialoprotein) = partly calcified

25
Q

How do we assess implants clinically?

A

Radiographs (poor resolution) and resonance frequency analysis (measure resistance to vibration of the abutment in the surrounding bone) = can convert to number which can be compared against other implants

26
Q

How do we no longer assess implants clinically?

A

Gripping with forceps and wiggle

27
Q

What is failure of implants correlated with?

A

Interposition of fibrous tissue between implant and bone

28
Q

What classifies as failure of an implant?

A

Mobility, pain, gingival inflammation, bone erosion, fracture

29
Q

What are the 3 different categories of compromising factors for implants?

A
  • poor surgical technique
  • Poor design
  • patient related factors
30
Q

What is a poor surgical technique?

A

Infection, overheating of bone, over-instrumentation

31
Q

What is a poor design?

A

Implant surface factors, shape of implant, overloading due to poor prosthetic design, loading too early

32
Q

What are patient related factors?

A

Limited available bone, poor oral hygiene, bruxism, age, smoking, radiotherapy, medications

33
Q

Why can implants not be placed in a growing child?

A

Implant becomes ankylosed to bone = stops jaw being able to grow normally = ‘sinking implant’

34
Q

What 4 factors do we promote to improve the osseointegration process?

A
  • Faster and stronger bone formation
  • Better stability
  • More rapid loading
  • Improved clinical performance in areas of poor quantity/quality of bone
35
Q

Which 3 ways do we achieve better osseointegration?

A
  • use surface topography to enhance osteoconduction
  • use surface coating to provide biological means to manipulate the type of cells that grow on the implant surface
  • use of implant as a vehicle for delivery of a bioactive coating that may achieve osseoinduction along its surface
36
Q

What have studies for using surface topography to enhance osteoconduction shown?

A

Osteoblasts might attach better, spread and proliferate on smooth surfaces but differentiate faster, produce higher levels of growth factors and mineralise faster on rougher surfaces

37
Q

What have studies for using surface coating to provide biological means to manipulate the type of cells that grow on the implant surface shown?

A

Superior initial rates of osseointegration have been achieved, experimentally long term failure is caused by delamination of coating and particle release from implant surface = need longer term studies to be sure, also no increase in BIC or osteoblast differentiation shown yet, and non-specific absorption of plasma proteins may occur with unfavourable interactions with inflammatory molecules

38
Q

What have studies using implants as a vehicle for delivery of a bioactive coating that may achieve osseoinduction along its surface?

A

-BMPs and PDGF enhance osteogenesis