Mineralization is a Process taking place in all the calcified structures in the body like the bone & enamel.
It is defined as the deposition of the mineral salts in and around the organic matrix to make it a calcified structure.
The mineralization process is based on 2 mechanisms:
- Booster Mechanism
- Seeding mechanism
And it is explained with the help of 3 Theories:
- Booster Theory
- Seeding Theory
- Matrix Vesicle Theory
The theories explain the process of mineralization in different ways, so lets know about them:
Boosters Mechanism: According to this theory due to the concentration/action of the enzymes the concentration of the calcium and phosphate ions which are building stones of mineralization increases to such a level that would lead to their precipitation.
Seeding Mechanism: It refers to a presence of a seeding or nucleating substance which acts a mould (or) template on which the crystals are deposited, the seeding substance resemble apatite crystals.
Matrix Vesicle theory: This theory states that, due to the presence of vesicles containing apatite crystals near each cartilage cell which aggregate and form a matrix which is mineralized.
Now going into the details of each Mechanism:
Booster Mechanism: There are 2 theories which explain this mechanism of mineralization
Robinson’s Phosphatase theory: According to him the presence of alkaline phosphatase releases the ions which take part mineralization and increases their concentration to such a level that their precipitation is seen.
Objections: As alkaline phosphatase is present even in tissues which do not calcify.
Cartier’s theory: According to him there are 2 types of substances which inhibit and one which induce the process, so with proper control of their concentrations the mineralization takes place.
Inducer: Adenosine triphosphate
Seeding Theory : It was made on account of the shortcomings of the booster theory, and the experimental studies revealed collagen to act as a seed, with apetite crystals forming on the collagen fibers.
The possible seeding substances are:
- Chondroitin sulphate
Matrix Vesicle Theory: According to this theory, due to the presence of vesicles containing apatite crystals near each cartilage cell which aggregate and form a matrix which is mineralized.
There are 2 types of vesicles:
Type I Vesicles: These are substances extruded from the cartilage cells.
Cause breakdown of proteoglycans and GAG.
Type II Vesicles: These are detached pieces of cartilage cells, are bounded by trilamellar membrane.
Promote mineralization by a blend of booster and seeding mechanisms.