Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biomaterials > Bioactive glasses and glass ceramics 1 > Flashcards

Bioactive glasses and glass ceramics 1 Flashcards

1
Q

What type of response do bioactive materials elicit at the tissue-implant interface?

A

Elicit a specific biological response at the tissue-implant interface that results in the formation of a chemical bond
include glasses, glass-ceramics, and ceramics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do bioactive materials differ in terms of?

A

Mechanism
Rate
Thickness of interfacial layer
Strength of bonding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of layer do bioactive glasses, glass ceramics, and ceramics form at the implant-tissue interface

A

Undergo time dependent modification of the implant surface
From a carbonated hydroxyapatite layer with tissue Very VERY strong interfacial adhesion
Some glasses, like 45S5 bio glass, also bond to soft tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the carbonated hydroxyapatite layer structurally and chemically close to

A

The inorganic phase of bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Bone composition

A

70% Mineral phase
30% Organic phase
2 % Cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Mineral phase of bone components

A 
95% Hydroxyapatite
Magnesium
Sodium
Potassium
Fluoride
Chloride
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Organic phase of bone components

A

98% matrix made of:

  • 95% collagen
  • 5% non collagenous proteins (BMO, TGFß: 2% NCP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Cells phase of bone components

A

osteoblasts
osteocytes
osteoclasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Region A composition of bioactive glass and glass ceramics

A

Bone bonding glasses

All glasses contain 6wt% P2O5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Region B composition of bioactive glass and glass ceramics

A

Inert materials
Elicit a fibrous capsule at the implant-tissue interface
Greater than 60% SiO2
Used for window, bottles, and microscope slides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Region C composition of bioactive glass and glass ceramics

A

Resorbable glasses

Degrade after 10-30 days implantation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Region D composition of bioactive glass and glass ceramics

A

Not technically practical

Has not been tested as implants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Region E composition of bioactive glass and glass ceramics

A

Inside dashed line of diagram
Soft tissue bonding glasses
ex: collagenous tissues
Ib > 8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Five principal components of bioactive glasses and glass ceramics

A 
In order of prevalence:
SiO2
Na2O
CaO
CaF2 (only in 45S5F)
P2O5
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Compositional features of bioactive glass (distinguish them from normal glass)

A

Contain 6 wt% P2O5
Have less than 60 mol% SiO2
High Na2O and CaO content
High CaO/P2O5 ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Does lowering or increasing CaO/P2O5 ratio reduce bioactivity?

A

lowering the ratio reduces bioactivity

17
Q

Does the addition of 12.5% CaF2 affect bioactivity?

A

No, it does not affect bioactivity

18
Q

What does in addition of 3% Al2O3 in a bioglass do?

A

It stops the bone bonding ability

19
Q

Bonding mechanism of bioactive glasses

A

As bioglasses react with aqueous environment of body, chemical and structural changes occur over time
Chemical composition and pH of solution change as accumulation and dissolution of products changes

20
Q

What happens when a bio implant is bonded to a bone?

A

Carbonated hydroxyapatite is formed

21
Q

What happens when a bio implant is bonded to soft tissue?

A

Collagen fibrils are chemisorbed through electrostatic, ionic, and hydrogen bonding

22
Q

Chemical reaction stages of bioactive (glass) implants with bone

A
  1. Rapid ion exchange
  2. Si-OH group formation
  3. Silica-rich layer formation
  4. Amorphous calcium phosphate
  5. Crystalline hydroxyapatite
23
Q

Step 1 of bioactive implants chemical reaction: ion exchange

A

Initiation of rapid cation exchange of Na+ and Ca2+ ions from the glass with H+ from solution
Usually controlled by diffusion
Hydrolysis of sola groups creates silanols (Si-OH)
pH increases

24
Q

Step 2 of bioactive implants chemical reaction: Si-OH group formation

A

Cation exchange increases [OH- ], leading to attack of silica glass network
Soluble silica lost in the form of Si(OH)4, resulting in breakdown of Is-OSi bonds and continued formation of Si-OH at the glass solution interface
Interface controlled action with t^1 dependence

25
Q

Step 3 of bioactive implants chemical reaction: Silica-rich layer formation

A

Condensation reaction takes place
result: depolymerization of SiO2 rich layer on surface of the glass that is depleted in alkali (Na+) and alkaline earth cations (Ca2+)

26
Q

Step 4 of bioactive implants chemical reaction: Amorphous Calcium phosphate

A

Migration of Ca2+and PO43-groups through the SiO2 rich surface layer to form an amorphous CaO-P2O5-rich film on top of the SiO2-rich layer.
CaO-P2O5-rich film then grows by the incorporation of more soluble calcium and phosphate ions from solution

27
Q

Step 5 of bioactive implants chemical reaction: Crystalline hydroxyapatite

A

Crystallization of the amorphous CaO-P2O5 film by incorporation of OH ̄ and CO32- to form a mixed carbonated hydroxyapatite layer

Biomaterials (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions