Dental Problems

Pulp Physiology and Histology

Oral Precancer ErythroplakiaTooth is made of three parts -the outer hardest enamel, middle softer dentin and the inner pulp or blood vessels. Thus, when an infection or damage occurs it spreads in this process outer to inward, from tooth enamel to middle dentin to inner pulp. An infection to the pulp can be understood and the treatment can be done by knowing the dynamics of physiology and pathology. In this article, there is a brief discussion on the pulp physiology and histology. Let us examine them.

Pulp physiology:

Dental pulp can be defined as the special organ with an unique environment. It has an unyielding dentin surrounding the resistance, resilient softer tissue of mesenchymal organ reinforced with the ground substance. It also has a closer relationship between the peripheral cell, dentin and the odontoblasts. Thus, making it as a functional entity which is sometimes also known as the pulp-dentin complex.

The tooth pulp has a very high circulatory force. This is because of its fluid interchanging between the tissue and the capillaries, which maintains the hydrostatic pressure within the non-compliant chamber. This hydrostatic pressure is known as the intra pulpal pressure. It is normally about 10mm of Hg (mercury) and it varies with every arterial pulse. The pulp doesn’t have a consistent in itseffective collateral circulation, even though the teeth have accessory canals. Hence, a pulpal injury irrespective of different causes is frequently irreversible and painful.

Nerve fibers responsible for transmitting pain are A delta (fast pain) and polymodial fibers (slow pain).


The pulp is described as having two regions, central zone and peripheral zone.

  • Central pulp zone:

    • The main body of the pulp occupies this area, which contains a core of loose connective tissue (stroma) bearing large nerves and blood vessels and branch out to supply to outer pulp layers.
    • Outlining the central zone is an area that is richly populated with undfifferentiated mesenchymal cells (reserve cells) and fibroblasts, and is referred to as the cell rich zone.
    • The principle extra cellular components are ground substance and collagen.
  • Peripheral zone:

    • Peripheral to the central area is the sub-dentinoblastic region of the pulp or zone of Weil.
    • This appears as a cell free zone which may diminish in size or temporarily disappear.
    • Plexuses of capillaries and small nerve fibers ramify in this layer deep to the odontoblastic layer.
    • The nerve fibers do not have their outer wrapping (mycelin sheath) and terminate into naked, free fibers as dendrites (free nerve endings), acting as specific receptors for pain.
    • On account of these free nerve endings pulp demonstrates pain as the only sensation irrespective of the stimulus.

The above article discusses briefly about the pulp physiology and histology.

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