Dentin

DENTIN

It is a highly mineralized tissue, composed of about 70% of inorganic material (hydroxyapatite crystals), about 20% of organic base, which are mainly of type I collagen fibers (highly mineralized) and 10% water. This allows the dentin has a certain minimum degree of flexibility, serving as support for the glaze will not crack.Is a yellowish color, which gives color to the tooth. Asdentin is a highly permeable tissue when there are problems of dental pulp necrosis or hemorrhage pulpal easily pigmented.
The dentin is a sensitive tissue. When stimulated with actors directly or indirectly, painless, although its structure has no innervation, this is because the tubes containing cell processes surrounded by fluid, which moves the effect of heat, cold, air blast, etc. .1. STRUCTURE

1.1. Tubules
Are very thin 2 to 2.5 microns in diameter. Traverse the entire thickness of dentin,. Curve and have an orientation perpendicular to the surface. There are (depending on the type and area of the tooth) about 40,000 tubules per mm 2 of surface.
As observed in perpendicular cut, inside the cell processes are observed, occupying almost the entire thickness of the tubule.Among thecell membrane and the tubule wall is a space called periodontoblastic, where tissue fluid (which is why it is so hydrated dentin). The secret odontoblast an organic substance that is part of the inner wall of the tubule, called the lamina limitans.Dentinal tubules on the end, especially in the crown, have ramifications (which sometimes generates most sensitive areas in the dentin in this sector),also between neighboring tubules exist side bridges.
There is a different number of tubules per unit of measurement on the outer and inner dentin. For example, in the coronal dentin is approximately 20,000 tubules per square millimeter of enamel around 45,000 per square millimeter and near the pulp. This implies that the outer part of dentin is stronger because it has more mineral between thetubules.

1.2. Odontoblast or fibers Tomes.
The odontoblast cell has an extension that fills the dentinal tubule, if the tubules are branched or forming bridges side, the extension also.
In a tubular cross section shows the lamina limitans, deeper into the space occupied by fluid and odontoblast, which has vesicles, filaments, microtubules and some mitochondria.
This extension is active becausethe cell is synthesizing and delivering periodontoblastic elements into space.

1.3. Intertubular dentin
Dentin is left between the dentinal tubules. Has collagen (produced by odontoblast) mineralized by 70%. The fibers are arranged perpendicular to the tissue forming a dentinal tubule.

1.4. Peritubular dentin.
Is what is forming the odontoblast as it progresses towards the pulp. It ismore mineralized than intertubular dentin: 78-80%. Is a hyper-ring. As it approaches the odontoblast, peritubular dentin is lower reach does not exist near the odontoblast, because the new odontoblast is forming.

( dentine at the outer boundary: the dentin was formed without odontoblast because the odontoblast was there. In a 10-15 microns thick collagen is perpendicular to dentinal tubule, but ismore disordered and parallel, this area is called mantle dentin.

( Dentin in an intermediate sector, this whole area is called dentin circumpulpar.

( very close to the odontoblast dentine, the collagen is mineralized, this sector is called predentin. The predentin is very pale and with a colored balloons, the limit is irregular. All this is due to the way in which mineralized collagen, thisis not a continuous front of mineralization, but mineralization cores, called globules of mineralization, when joining these points leave an irregular boundary and winding.

2. Dentin formation

• increase lines or lines of Owen, representing the steps of duty cycle of odontoblasts.

• interlobular spaces or spaces Czermak: near the boundary are observed coronary colored spaces,...