Mineralization

Question 1

Describe ionic replacement

Answer 1

• any ion can be substituted
• F- may substitute OH-
  stabilises the lattice
  more acid resistant
  F- and prevention

Question 2

describe F- and apatite solubility

Answer 2

fluorapatite requires larger pH falls to result in dissolution of mineral

Question 3

what are the theories of mineralisation?

Answer 3

alkaline phosphatase - earliest theories
Nucleation theories: formation of a crystal from a solution
- homogeneous nucleation
- heterogeneous nucleation
Matrix vesicles - produced by cell to help odontoblast/osteoblast with remineralisation

Question 4

describe homogeneous nucleation

Answer 4

• homogenous nucleation of hydroxyapatite is very difficult to achieve
• Importantly hydroxyapatite crystals do not spontaneously form in the blood stream
• Ions in serum can sustain crystal growth

Question 5

describe heterogeneous nucleation - epitaxy

Answer 5

• a foreign solid will assist nucleation of a crystal
• especially if it has a similar lattice structure
• epitaxy (greek = “arranged upon”)
• organic matrix may act as an epitactic agent
• other molecules help overcome problems and allow for crystallisation organic matrix is the epitactic agent

Question 6

describe matrix vesicles

Answer 6

• produced by cells
• contain high concentrations of Ca2+ and PO4 3- ions
• provide ideal microenvironment for crystal formation and growth
• released into extracellular tissue
• crystals grow and rupture vesicle
• help initiate mineralisation in a tissue
• matrix vesicles involved in bone mineralisation