The resilience to noxious insults and the inherent
healing potential of the dental pulp is well recognized.
Since the pulp is relatively incompressible, the total
volume of blood within the pulp space cannot be greatly
increased. Hence careful regulation of pulp blood flow
is of critical importance and alterations in pulp micro-circulation
may be the first to occur with the onset of
pulp inflammation.
In general, the pulp microcirculation is supplied
through the maxillary artery, which is a branch of the
external carotid artery. The maxillary artery leads into
the dental artery and enters the tooth via arterioles
feeding each individual pulp microvasculature. Pulp
vessels are arranged in a hierarchical system:
the arterioles course up centrally and give off branches to
form a capillary network at the periphery of the pulp
and the blood drains into venules at the centre of the
pulp. The capillary network provides the odontoblasts
with a rich source of nutrients. The vascularity of the
pulp is comparable with that of the most vascular parts
of the brain and the tongue, indicating that the pulp
is a highly vascular tissue.
One study has shown
that pulp vessels are immune to artherosclerosis in
monkeys.
The dental pulp has a relatively high blood flow. It is
estimated to be 40–50ml/min/100g of pulp tissue in a
mature tooth as determined by radioactive microsphere
techniques.
This flow is relatively high, compared to
that of other oral tissues and skeletal muscle.
Numerous shunt vessels have also been observed in the
dental pulp, although their function is less well
understood.
These vessels can be arterio-venous
anastomoses, venous-venous anastomoses or U-turn
loops. They provide a direct communication between
arterioles and venules, hence bypassing the capillary
bed. Considerable shunting occurs in the apical half of
the pulp.
When the intrapulpal pressure rises during
inflammation, these shunt vessels may open up to
reduce the intrapulpal pressure so that the normal
blood flow is maintained.