Ceramic bio materials

Question 1

Define Ceramic

Answer 1

InOrganic, non metallic metal.
Crystaline compounds formed between metallic and nonmetallic elements
These crystals have strong bonds and are therefor hard

Question 2

Glasses

Answer 2

Ceramic composition but not crystaline
Bioactive glasses work with the surface to form a calcium phosphate layer on their surface
- They are an inorganic melt colled to a solid form without crystalisation
- An amorphous (lacks long range order like you would expect in a solid) solid
Possesses short range atomic order –> therefor brittle

Question 3

1st Generation Biomaterial

Answer 3

Bioinert- minimal interaction with the body tissues
Generally forms a fibrous capsule
Alumina, Zirconia

Question 4

2nd Generation Biomaterial

Answer 4

Biodegradable (Resorbable)
This dissolves after a specific period of time ( need to ensure this is the required time )
Calcium phosphates and calcium sulphates

Bioactive - surface reactive
Tighly bonded to living tissues
Hydroxyapatite

Question 5

3rd Generation Biomaterial

Answer 5

Scaffolds made of biologically active molecules
This stimulates living tissue regeneration
Bioglass

Question 6

What type of biomaterial is calcium phosphate and give and example of how it is used

Answer 6

2nd Gen- Biodegradable

Used as bone graft substitute to replace bone loss

Question 7

Why do we use bioceramics

Answer 7

Initially used instead of metals in order to increase biocompatability

Question 8

Three basic types of biomaterial

Answer 8

• Bioactive
• BioInert
• Bioresorbable

Question 9

What type of biomaterial is Glass ceramic and give and example of how it is used
Give definition
Give an example of a commercially available version

Answer 9

BioActive
Glass- ceramics - a polycrystaline solid prepared by controlled crystallisation of glass.
Vertibral prosthesis to replace those removed after surgery
- It was the first biomaterial to display bioactiviity in the bone system
-Capable of direct chemical bonding with the host tissue
- Stimulatory effects on bone building cells
- The structure does not shrink during crystalisation so the net glass shape is retained. This makes it good for non load baring implants such as maxillo facial repair.
Example: BioGlass which bonds well with bone. It is sometimes used ina powder form to encourage bone healing- occurs because it forms hydroxyapatite which encourages cell adhesion adn releases calcium.

Question 10

Bioinert ceramics- most common example, uses and +ives

Answer 10

Alumina oxide 
Zirconia is also very popular for use in hip sockets 
Highly stable 
Good mechanical properties
Good biocompatability 
Little fibrous capsule formation 
Non degradable 
Don't cause osteolysis

Question 11

What ceramic is known as the ultimate ceramic and why
Current problems
How are we over coming them

Answer 11

Zirconia
It has great properties when dry- super strong
As soon as it gets wet it fails
Combining it with alumina means the new material has improved hardness and wear resistance. It also is provided with a high strength and density from the alumina.

Question 12

Give an example of a bioactive ceramic

Answer 12

Calcium phosphates
These are good for coating and scaffold but have poor mechanical properties
Bone mineral is carbonated hydroxyapatate which is a type of calcium phosphate so this works well for scaffolding bone

Question 13

What is the chemical formula for hydroxyapatate

Answer 13

Ca10(PO4)6(OH)2

Question 14

What is an example of a hydroxyapatite ceramic and what are they good for

Answer 14

TRICALCIUM PHOSPHATE

• Highly resorbable
• Especially useful in cements
• Not good at load baring as resolution rate is so high
• If used individually, work well as coatings
• If mixed with other materials can be used for other things

Question 15

What are the mechanical properties of glass ceramic influenced by

Answer 15

• Properties of crystalline phase
• Grain size
• Intergranular bonding
• Crystal orientation
• Percentage crystallinity - some residual glass pphase impves some properties such as bioactivity- dont want this to be 100%

Question 16

Give two examples of implantable bone fillers from bovine bone

Answer 16

Endobon
- Osteoconductive Hydroxyapatite ceramic
- Used as a bone graft substitute
- Biological origin
- Used in permanent fillings for trauma surgery and orthopedics
Bio-Oss
- Osseointegrates with newly formed bones
- Is resorbed by adjacent osteoclasts

Question 17

What is Corraline Hydroxyapatite

Answer 17

Sold as Pro Osteon
Hydrthermically converted marine coral exoskeletons converted into hydroxyapatite
The interconnected porous structure is similar to that of bone- Provides a strong natural foundation for new bone ingrowth and offers strong support
The strength once healed is similar to that of the actual bone
No implant rejected and has no immune response or disease transmission
The healing rates are equivalent to that of the patients own bone

Question 18

Define Composits

Answer 18

Consisting of two or more chemically distinct constituents in a macro scale having a distinct interface

Question 19

Define Composits

Answer 19

Consisting of two or more chemically distinct constituents in a macro scale having a distinct interface

Question 20

What advantages does using a composite have

Answer 20

• Improves mechanical properties like toughness
• Improves degradability
• Can combine strength with cell adhesion properties
• Can be used to allow the release of a drug/growth factor whilst maintain structure
• Higher tensile strengths and moduli that both biological materials and polymers
• They can be designed with crack deflecting abilities though laminations, voids and fibre reinforcements

Question 21

What materials can be mixed with bioceramic in order to reinforce them

Answer 21

Carbon Fibre 
Polymer fibres- Kevlar used in dentistry 
Ceramics
Glass fibres 
PLA and PGA cen self reinforce

Question 22

Give an example of a commmercially available biomaterial composit

Answer 22

HAPEX

Hydroxyapatite and high density polyethene- the cells attach themselves to the hydroxapatite and grow

Question 23

Electrospinning Composites

Answer 23

Nanoparticles are dissolved in the same solvent as PCL to make a solution with dispersed particles and then are spun using standard methods
This often requires a compromise between mechanical and biological properties