Dental Pulp

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Dental Pulp

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Introduction

• Non-mineralised vascular tissue
• Responsible for the formation of dentine
• Contained within pulp chamber and root canal of
  the tooth.
• Remains active through out life.

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Organisation

• Specialised connective tissue
• Odontoblasts are at the periphery of the tissue
• Nerve terminals of the trigeminal afferents and
  specialised antigen presenting cells which detect
  external stimuli and initiate a response to them

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Organisation

• Rest of the pulp serves to support.
• Blood vessels and nerves enter and leave the root
  canals through an apical foramen at the root end.

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Sections
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Composition

• Loose connective tissue, whereby it is made of a
  combination of cells embedded in an extracellular
  matrix of fibres in a semi-fluid gel.
• 75 water, 25 organic material.

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Composition

• Fibrous Matrix
• Non-Fibrous Matrix
• Cells

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Composition

• Fibrous Matrix
• Type I collagen is the principal fibrous
  component.
• Scattered irregularly as thin fibrils which
  bundles as fibres
• Alligned approx parallel to the predentine
  surface.
• Type III collagen is also present in large
  amounts
• Type V and VI are also present in small amounts.
• The greatest collagen concentration is at the
  apical portion.

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Non Fibrous Matrix

• Glycosaminoglycans(GAGs)
• Proteoglycans
• Fibronectin
• Laminin

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Cells

• Odontoblasts
• Fibroblasts
• Defence Cells T lymphocytes, macrophages,
  dendritic antigen-presenting cells.
• Undifferentiated cells pluripotential,
  primitive mesenchymal cells

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Odontoblasts

• Form a layer of lining on the periphery of the
  pulp and have a process extending into the
  dentin.
• At the coronal portion the cells are columnar,
  mid-portion is cuboidal and apical is flattened.
• Morphology of cells relates to its activity
• Odontoblasts have processes which begins at the
  neck of the cell body
• Process does not have cell organelles but has
  microtubules and filaments (terminal web)

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Fibroblasts

• The most common cell found in the pulp
• Found more in the coronal portion of pulp which
  forms the cell rich zone.
• Function is to form and maintain the pulp matrix
  (collagen ground matrix)

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Undifferentiated Ectomesenchymal Cells

• Represents the pool from which connective tissue
  cells of the pulp are derived.
• May give rise to odontoblasts and fibroblasts
• Found in cell-rich area and pulp core
• Diminishes with age

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Macrophages

• Centrally located in the pulp
• Involved in elimination of dead cells
• Lymphocytes
• Presence of T lymphocytes

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Dendritic Cells

• Dendritic process extend between odontoblasts.
• Capture and present foreign antigen to the T
  cells.
• Non phagocytic

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Functions

• Nutrition
• Sensory
• Inductive
• Defensive
• Formative

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Regions

• In histological sections, 4 distinct zones can be
  identified
• Odontoblastic zone located at the periphery of
  the pulp adjacent to the dentine.
• Cell-free zone beneath the odontoblast is a
  cell free zone also known as the zone of Weils.

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• Cell-rich zone beneath the cell-free zone is an
  area with a high cell density.
• Pulp Core is the area where major blood vessels
  and nerves are found.

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Age Related Changes

• Dental pulp gets smaller because of secondary
  dentine deposition.
• Older pulp is less vascular and more fibrous
• Innervation is reduced
• Mineralises in the form of pulp stones

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Dentine and Pulp

• Closely related developmentally and functionally.
• Both tissues are derived from the neural crest
  cells of the dental papilla
• Pulp communicates to the oral cavity via dentinal
  tubules

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Theories of Dentine Sensitivity

• Direct Innervation
• Dentine nerve terminals extend to the DEJ and
  hence initiate an action potential directly.
• Transduction
• Odontoblast can transduce a mechanical stimulus
  and transfer that signal to a closely opposed
  nerve terminal.

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Contd

• Hydrodynamic Theory
• Due to the fluid movement in the dentinal tubules
  in response to external stimuli, the nerve
  terminals within the dentinal tubule and
  odontoblast layer initiate an action potential.
• Rapid movement will cause pain.

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The End!

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