Dental Pulp

• what is the dental pulp?

  a mass of connective tissue that resides within the center of the tooth, directly beneath the layer of dentin.

  
• what are the 3 functions of the dental pulp?

  • Production, maintenance, and repair of dentine (odontoblasts)

  • Sensitivity (nociception and proprioception)

  • Immune response (defense against pathogens)
• what are the Major cell types and structures found in the pulp?

  • Odontoblasts

  • Fibroblasts

  • Undifferentiated ectomesenchymal cells

  • Dental pulp stem cells

  • Inflammatory cells

  • Nerves

  • Lymph vessels

  • Blood vessels
• what are the 4 regions of the pulp from the periphery to the center?

  • Odontoblastic zone

  • Cell-free zone of Weil

  • Cell-rich zone

  • Pulp core

  
• describe the Odontoblastic zone


  • Forms the outer periphery of the pulp

  • Odontoblasts line the walls of the pulp and produce the predentine, which mineralizes into mature dentine

  • Odontoblasts are typically long, columnar cells, but may be flatter in more apical (rootward) regions of the pulp

  • These cells provide the link between the pulp and the dentine via the odontoblast processes within the dentine tubules

  
• describe the Cell-free zone of Weil

  • Rich in blood capillaries and nerves

  (important in maintaining and supporting the odontoblast layer)

  
• describe the Cell-rich zone

  • A region rich in fibroblasts (the main cell type found in this zone)

  • These cells form and maintain the pulp matrix (collagen types I and III, ground substance)

  • Undifferentiated ectomesenchymal cells are also found here

  -> These cells may give rise to new odontoblasts or fibroblasts depending on the stimulus

  
• describe the Pulp core

  • Contains the principal vascular network (blood vessels), which enters the pulp via the apical foramen

  • also contains the lymph vessel network

  
• what do Nerves and vasculature enter the pulp through?

  a hole at the root apex called the apical foramen.

  
• what nerves enter the dental pulp?

  sensory afferent nerves of the trigeminal nerve (fifth cranial nerve)
• in the dental pulp, the nerves branch as they extend coronally to form a large network in the cell-free zone.

  what is the network called?

  plexus of Raschkow

  
• where is the plexus of Raschkow primarily situated?

  in the cell-free zone of the pulp, however, some nerve endings extend into the odontoblastic layer and even into the dentine tubules

  
• How can dentine be such a sensitive tissue to temperature, changes in osmolarity, and physical stimuli?

  there are 3 hypotheses:

  
  

  1. Sensitivity is due to stimulation of nerve endings that are found within the dentine tubules

  
  

  2. The odontoblasts are the receptors of stimuli and are coupled with nerves in the pulp

  
  

  3. Hydrodynamic theory: fluid movement through the tubules is sensed by the free nerve endings in the plexus of Raschkow

  
• 1. Sensitivity is due to stimulation of nerve endings that are found within the dentine tubules

  
  

  state what supports and is against this hypothesis

  • Support: Some nerve endings do extend into the dentine tubules

  • Against: Relatively few tubules contain nerve endings and sensitivity does not depend on the stimulation of these particular nerves to cause discomfort

  
• 2. The odontoblasts are the receptors of stimuli and are coupled with nerves in the pulp

  
  

  state what supports and is against this hypothesis

  • Support: Odontoblast processes extend into the dentine

  -> to act as receptors?

  • Against: Not clear if odontoblasts can send signals to nerves in the pulp, and no clear indication of a synaptic connection between nerves and odontoblasts

  
• 3. Hydrodynamic theory: fluid movement through the tubules is sensed by the free nerve endings in the plexus of Raschkow

  
  

  state what supports this hypothesis

  • Support: dentine tubules are fluid- filled, fluid exits through exposed dentine tubules naturally (when dried, more fluid is lost, leading to more pain)

  -> Explains why pain can be induced from heat, mechanical probing, hypertonic solutions, dehydration (all of which would move fluid within the tubules)

  
  

  = PREDOMINANT THEORY

  
• state the Immune responses of the pulp

  • Innervation and the continued presence of odontoblasts and other cells make the pulp-dentine complex very responsive to environmental stimuli

  • Dental caries progression is slowed by closure of dentine tubules

  • Attrition can stimulate sclerotic dentine production

  • Larger physical or bacterial stimuli can trigger tertiary dentine production
• abnormalities of the dental pulp- what are pulp stones?

  mineralisations within the dental pulp, possible causes include disease, developmental abnormalities

  
  

  -> Relatively common and can form from a variety of host tissues (pulp collagen bundles, epithelial cells, blood thrombi)