The document discusses three main theories of mineralization: 1) The booster/Robinson's alkaline phosphatase theory which proposes that alkaline phosphatase hydrolyzes organic phosphates, increasing phosphate ions and allowing precipitation of hydroxyapatite crystals. 2) The collagen seeding theory where calcium binds to proteoglycans between collagen molecules, phosphoproteins attach, and phosphate ions are released to form hydroxyapatite crystals at collagen gaps. 3) The matrix vesicle theory where matrix vesicles bud off cells, alkaline phosphatase hydrolyzes organic phosphates inside the vesicles, forming the first apatite crystals which then grow and rupture into the organic matrix.

1. THEORIES OF MINERALISATION

2. MINERALISATION
 Process by which minerals are deposited
in the organic matrix, which is capable of
accepting minerals
 Synthetic cells + Alkaline phosphatase =
mineralisation
 Inorganic portion – calcium hydroxyapatite
crystals –
Ca10 (PO4) 6 (OH)2

3. NUCLEATION
 First Aggregation of ions to form crystals
Nucleation
Homogenous Heterogenous

4. THEORIES
Booster theory or Robinson’s
Alkaline phosphatase theory
Collagen seeding theory
Matrix vesicle theory

5. Booster theory /
Robinson’s Alkaline phosphatase
theory
Alkaline
phosphatase
(oragnic matrix)
Hydrolyses
organic
phosphates
(Pyrophsphates)
–
Plasma &
Calcifying tissue
Release
phosphate ions
Increase in
phosphate ions
Precipitation
Phosphate ions +
Calcium ions
Hydroxyapatite
crystals

6. Collagen seeding theory
 Nucleating substance Collagen [Seed] – Template
Calcium
Binds to
Proteoglycans
between Collagen
molecules
Proteoglycans
removed by
enzyme action
Phosphoproteins
get attached to
collagen
Alkaline
phospatase break
down
phosphoproteins
Phosphate ions
released
Phosphate ions +
Calcium ions
Hydroxyapatite
crystals at the
gap zone of
collagen

7. Matrix vesicle theory
 Matrix vesicle – organelles of cellular origin [matrix of
cartilage, bone, other hard tissues] – bud off from synthetic
cells
Matrix vesicle
ATPase,
Alkaline
phosphatase,
& Pyrophosphatase
+
Ca2+ ions bound to
phospholipids
Alkaline phosphatase
hydrolyse organic
phosphates to
phosphate ions
Phosphate ions bind
to calcium
Apatite crystals
formed
[1st crystal formed]
Crystal grows inside
vesicle by addition of
ions
Matrix vesicle rupture
Crystals released into
organic matrix
Crystal grow by using
ions in tissue fluid