Pulp Zones

The dental pulp is the soft connective tissue of the tooth that supports the dentin.

The pulp cavity exhibits four zones as you progress from the dentin-pulp junction toward the center of the pulp cavity:

Odontoblasts are pulp cells that are found in the peripheral layer closely related to the predentin.
The cells have a basally located nucleus with supraneuclear rough endoplasmic reticulum and golgi apparatus.
Mitochondria and lysosomes are found throughout the cytoplasm Dentin pulp complex.
The major function of odontoblast is to produce and secrete extracellular matrix of the predentine and bio- mineralization of the dentine.
They continue to produce predentine throughout life but the rate of depositions reduces as age advances.
The major protein secreted by odontoblast is Type I Collagen Odontoblasts have a process extending from the cell body up till the DEJ contained in a dentinal tubule, called the odontoblastic process.
There are multiple lateral odontoblastic processes originating from the main process.

This zone lies below the odontoblast and is prominent in the coronal pulp.
As the name suggests this area of pulp is nearly devoid of any cells Zones of the pulp.
40 microns wide &relatively free of cells.
Traversed by –
1. Blood vessels
2. Unmyelinated nerves
3. Cytoplasmic process of fibroblasts

This zone is beneath the cell free zone.
This area of pulp is characterized by the presence of major nerves and vessels of the pulp Zones of the pulp.

The constituents of this zone are basically the same as those in the pulp proper:

Fibroblasts
Undifferentiated mesenchymal cells
Defense cells (macrophages and lymphocytes)
Blood capillaries
Nerves
This zone is discernible due to its higher density of fibroblasts than the pulp proper and is much more prominent in the coronal pulp than in the root pulp

From the cell-rich zone inward is the central connective tissue mass known as pulp proper or pulp core;

This zone contains:

Fibroblasts, the most abundan cell type;
Larger blood vessels;
Nerves;
Undifferentated mesenchymal cells and defense cells (macrophages are frequently located in the perivascular area);
Collagen-fiber bundles.

Histologic picture of dental pulp