22-01-2021

1

Department of Oral Pathology & Microbiology

SRM Dental College,

Theories of mineralisaTion

dr. a.ramesh KUmar

SRM Dental College, Ramapuram, Chennai, India

22-01-2021

2

MINERALISATION• Process by which minerals are deposited in the organic

matrix, which is capable of accepting mineralsmatrix, which is capable of accepting minerals

• Synthetic cells + Alkaline phosphatase = mineralisation

• Inorganic portion – calcium hydroxyapatite crystals –Ca10 (PO4) 6 (OH)2

22-01-2021

3

NUCLEATIONFirst Aggregation of ions to form crystals

Nucleation

Homogenous Heterogenous

22-01-2021

4

Booster theory / Robinson’s Alkaline phosphatase theory

Alkaline phosphatase

(oragnic matrix)

Hydrolyses organic phosphates

(Pyrophsphates) – Release phosphate ions

Increase in phosphate ionsphosphatase

(oragnic matrix) Plasma & Calcifying tissue

ions phosphate ions

PrecipitationPhosphate ions + Calcium ions

Hydroxyapatitecrystals

22-01-2021

5

Collagen seeding theory

Calcium

Binds to Proteoglycans

between Collagen molecules

Proteoglycansremoved by

enzyme action

Phosphoproteinsget attached to

collagen

Alkaline phospatase break

down phosphoproteins

Phosphate ions released

Phosphate ions + Calcium ions

Hydroxyapatitecrystals at the gap zone of collagen

22-01-2021

6

Matrix vesicle theory

Matrix vesicle

ATPase, Alkaline phosphatase,

& Pyrophosphatase

+Ca2+ ions bound to

Alkaline phosphatasehydrolyse organic

phosphates to phosphate ions

Ca ions bound to phospholipids

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