Ceramics

Question 1

Describe the long bone structure.

Answer 1

Spongy Bone:
AKA: Cancellous or Trabecular Bone
Very porous
High vascularized
Red bone marrow to make blood cells and platelets
Epiphyseal Line:
Point of union between epiphysis and diaphysis 
Yellow Bone Marrow: 
Makes fat cells, cartilage, and bones
Compact Bone:
AKA: cortical bone
Structural

Question 2

What is ossification?

Answer 2

Formation of bone

Question 3

What are osteoblasts?

Answer 3

cell that secretes bone matrix

Question 4

What are osteoclasts?

Answer 4

cells the degrade bone

Question 5

What are osteocytes?

Answer 5

for bone maintenance

Question 6

What are osteogenic cells?

Answer 6

osteoprogenitors, they differentiate and turn into osteoblasts

Question 7

Describe the tooth structure.

Answer 7

Enamel:
Hard outer surface
stronger than bone
96% hydroxyapatite
Dentin:
45% hydroxyapatite
33% organic
22% water
yellow in solar
Pulp:
living connective tissue
considered part of the dentin

Question 8

What are ceramic characteristics?

Answer 8

Brittle
High hardness
high thermal resistance
high electrical insulation
good corrosion resistance

Question 9

What are ceramic crystal structures described as?

Answer 9

ionic crystals

composed of ions rather than atoms

Question 10

What is considered for ceramic crystals?

Answer 10

the magnitude of charge and the size of the atoms

Question 11

What must a ceramic crystal be?

Answer 11

electrically neutral

Question 12

How do you find the coordination number of an ionic crystal?

Answer 12

Need to know the radius of anion and cation
Depends on nearest neighbors with opposite charge
Cations have smaller radius than anions
use rc / ra, too small for space, unstable

Question 13

What is the Ca/P ratio?

Answer 13

< 1 - dissolves in solution
> 5 - too hard, foreign behavior
1-2 is preferred

Question 14

What does bioinert mean?

Answer 14

does not interact with tissue and is not rejected
Advantages:
Little to no immune response
Maintain their physical and mechanical properties
Disadvantages:
Minimal bone ingrowth
appearance of non-adherent fibrous membrane
interfacial failure and loss of implant can occur

Question 15

What does bioactive mean?

Answer 15

It will interact with body
ability of a material to form a bond with living tissue
ability of a material to stimulate healing, tricking the system into thinking it’s a natural material
biodegradation: breakdown due to chemical or cellular actions

Question 16

Describe the bioactivity index.

Answer 16

Ib = 100 / t50bb
where t50bb is time required for more than a 50% bond
A higher value, the faster the rate of apatite formation on its surface

Question 17

Describe bioactive glasses.

Answer 17

Bioactive
easily alter their chemical composition to fine tune degradation rates
formed when molten ceramic is rapidly cooled
cannot observe crystal structure using microscopy

Question 18

What are calcium phosphate ceramics?

Answer 18

a major constituent of bone mineral
synthesized by mixing calcium and phosphate under acidic or alkaline conditions
not suitable for implants if Ca/P < 1

Question 19

Describe Hydroxyapatite.

Answer 19

amenable to a variety of substitutions
replacing F with OH increases crystallinity, crystal size, and stability, reduces solubility, found in fluoride toothpaste
can replace with carbonate to make it more soluble

Question 20

Describe B-tricalcium phosphate

Answer 20

Dissolves in wet media, rapid degradation, easily replace by bone