Dental Pulp 101: A Cellular And Structural Overview

Dental Pulp 101: A Cellular And Structural Overview

Describe briefly the microscopic structure of pulp.
Answer:

Structure of Pulp:

• The pulp consists of

1. Interceullar substance:

• The intercellular substances are dense and gel-like in nature.
• Its appearance varies from finely granular to fibrillar.
• It is composed principally of glycosaminoglycans, glycoproteins, and water.
• With age its composition changes.
• Initially, there occurs chondroitin A, B and hyaluronic acid, and glycoproteins in abundant amounts.
• Later all these substances decrease in amount.
• This reduction interferes with the function producing metabolic changes.
• This also results in irregularities in mineral deposition.

Pulp Functions:

• It supports the cells.
• It acts as the medium for the transport of nutrients from the vasculature to tire cells and of metabolites from the cells to the vasculature.

2. Fibroblasts:

• It is the most numerous cell type in the pulp.
• They are particularly numerous in the tire coronal portion of the pulp.
• They have typical stellate shapes.
• Adjacent cells are joined by intercellular junctions.
• The cytoplasm is homogenous with the abundant rough-surfaced endoplasmic reticulum, mitochondria, and other organelles.
• In young pulps, fibroblasts have a plump, cytoplasm and an extensive amount of all organelles for synthesizing matrix.
• With age, fibroblasts appear as flattened spindle-shaped cells with dense nuclei.

Fibroblasts Functions:

• Fibroblasts form and maintain the pulp matrix.
• They are capable of ingesting and degrading collagen when appropriately stimulated.
• They play an important role in inflammation and healing.
• They release inflammatory mediators, cytokines, and growth factors.

3. Fibers:

• The matrix of pulp consists of collagen fibers.
• These fibers exhibit typical cross striations at 64 nm and range in length from 10-100 nm or more.
• In the young pulps, single fibrils of collagen are found scattered between the pulp cells.
• With age, the collagen fibers increase in amount and organize into fiber bundles.
• The fibers are principally type 1 and type 3 collagen.
• The greater concentration of collagen generally occurs in the most apical portion of the pulp.
• Their presence may be related to environmental trauma.

4. Undifferential mesenchymal cells:

• The connective tissue cells of the pulp are derived from it.
• Depending on the stimulus, these cells may give rise to odontoblasts, fibroblasts, or macrophages.
• They are found throughout the cell-rich area and the pulp core.
• They appear as large, polyhedral cells possessing a large, centrally placed nucleus.
• They have abundant cytoplasm.
• They are the primary cells in very young pulp, but few are seen in pulps after root completion.
• With age, there is a reduction in these cells which reduces the regenerative potential of the pulp.

5. Odontoblast:

• They are the second most prominent cell in the pulp they are tall columnar cells with large oval nuclei
• The odontoblast morphology and its organelles vary with the functional activity of the cell.

Odontoblast Functions:

• Function primarily as secretory cells.
• They synthesize and secrete collagen from dentin and also the ground substance.

6. Defence cells:

• They are.
• Histiocyte or macrophage:
• They have irregularly shaped cells with short blunt processes.
• Their nucleus is smaller and more rounded and granular cytoplasm.

Mast cells:

• They are seen along vessels in the inflamed pulp.
• Their number increases during inflammation of the pulp.

Plasma cells:

• Their nucleus is small and the cytoplasm is basophilic.
• They are seen during inflammation and produce antibodies.

7. Other cells:

Eosinophil and lymphocytes:

• They are found extravascularly in the pulp.

Dendritic cells:

• They are bone-derived cells.
• Found in and around the odontoblast layer.

Dendritic cells Function:

• They capture and present foreign antigens to T-cells.