Ceramics And Polymers

Question 1

General benefits of ceramic implant materials

Answer 1

• Inertness in body fluids
• High compressive strength
• High hardness

Question 2

Problems with ceramics

Answer 2

• Do not bend easily at room temperature
• Susceptible to crack propagation
• Can undergo static fatigue

Question 3

Describe notch sensitivity

Answer 3

In ductile materials notch tips widen under load and stress risers decrease
In brittle materials fast fracture happens quickly

Question 4

Why are compressive stresses not considered as big of a problem with notch sensitivity?

Answer 4

Compressive stresses can be supported across cracks without extending flaws

Question 5

What is the first notable ceramic in our notes?

Answer 5

Aluminium oxide - Alumina - Al2O3

Question 6

What is the moh’s hardness grade for aluminium oxide

Answer 6

9

Question 7

What is the main use of Aluminium Oxide in implants

Answer 7

Hip ball construction (occasionally socket - acetabular cup)

Question 8

What happens during sintering?

Answer 8

Firing a powder pressed piece, but not melting it, to reduce pore size

Question 9

What is the second notable ceramic in our notes?

Answer 9

Calcium Phosphate

Question 10

What is the main use of Calcium phosphate?

Answer 10

Artificial Bone

Question 11

How is Calcium Phosphate obtained?

Answer 11

Processing sea coral or synthetic production

Question 12

What three factors affect the type of Calcium Phosphate ceramic that is produced?

Answer 12

Ca/P ratio
Presence of water
Impurities

Question 13

What is the form of Calcium Phosphate ceramic most closely related to bones and teeth?

Answer 13

Hydroxyapatite

Question 14

What kind of Calcium Phosphate would be more suitable for bone scaffolds?

Answer 14

Porous Calcium Phosphate

Question 15

How can Coralline (mostly Calcium Carbonate) be converted to Hydroxyapatite?

Answer 15

React with Ammonium phosphate under heat and pressure

Question 16

List the three types of polymer molecular structure from weakest to strongest

Answer 16

• Linear
• Branched
• Cross-linked

Question 17

What are the three classifications of biomedical synthetic polymers

Answer 17

Thermoplastics
Thermosets
Elastomers

Question 18

Name two Polyolefins

Answer 18

Polypropylene, Polyethylene

Question 19

What are the three ways that polyethylene is processed

Answer 19

• Low Density (LDPE)
• High Density (HDPE)
• Ultra-High Molecular Weight (UHMWPE)

Question 20

Two applications for LDPE and HDPE

Answer 20

• Lining of Catheters

- Porous graft (craniofacial augmentation)

Question 21

Main uses for UHMWPE

Answer 21

• Sliding surfaces in artificial joints with a metal pairing

- High load bearing joints (unbeatable)

Question 22

Main uses for Polypropylene

Answer 22

• Monofilament suture materials

- Meshes

Question 23

What is the most important application of polyamides?

Answer 23

Nylon (sutures)

Question 24

Name three alternative synthetic and non-biodegradable polymers

Answer 24

Poly(Vinyl Chloride) (PVC)
Polyurethanes
Silicone

Question 25

List three features of Methacrylates e.g. PMMA

Answer 25

Excellent Chemical Resistivity and high bio compatibility
Excellent light transparency
High index of refraction

Question 26

Hydrogels love____

Answer 26

Water (Hydrophilic)