Similarities between pulp and connective tissue (x5)
- cells - mainly fibroblasts
- collagen matrix
- ground substance / ECM
- blood vessels and nerves
- 75% water 25% organic
Differences between pulp and connective tissue (x7)
- specialised cells (odontoblasts)
- contained in a rigid chamber
- no fat cells
- no oxytalin fibres
- no mast cells
- blood vessels have a wide lumen and thin/narrow wall
- densely innervated
Name 4 pulpal cells
- odontoblasts
- fibroblasts
- undifferentiated ectomesenchymal cells
- Defence cells: macrophages, lymphocytes
Pulpal innervation
- 70-80% non-myelinated
- the rest: myelinated fibres: 90% Ad, 10% A-beta
- plexus of raschkow (in the cell free zone)
- marginal plexus (around odontoblasts)
Site of touch receptors
Periodontal ligament
Site of pain receptors
Dentine/pulp, periodontal ligament
Site of cold receptors
Gingiva, dentine/pulp
Name the three theories of dentinal sensitivity
- Dentine is innervated
- Odontoblast receptor theory
- Hydrodynamic theory
Where area in dentine is most sparsely innervated?
pre-dentine of pulp horn
What is the odontoblast receptor theory?
Stimulus transduction via the odontoblast process
Communication between odontoblast and primary afferents
What is the problem with the odontoblast receptor theory?
There is no evidence of electrical communication chemical synapses between odontoblast and nerves
Odontoblast process likely only extends 1/3rd into dentine
What causes outward fluid flow? (X5)
- cooling
- drying
- evaporation
- hypertonic solutions
- decreased hydrostatic pressure
What causes inward fluid flow? (X3)
- heating
- mechanical
- increased hydrostatic pressure
Which nerves are involved in the hydrodynamic theory?
Unmyelinated endings of A-delta and A-beta fibres
Functions of pulp x3
- dentine formation
- Defence and repair
- sensory
