SENSORY NERVES OF THE PULP

 

SENSORY NERVE TYPE FEATURES
Nerve endings of myelinated A-delta fibers ·     Involved in sharp pain sensations.

·     Most sensitive to stimuli that cause movement of dentinal fluid à “hydrodynamic stimuli”.

·     It is still unknown whether these receptors are present in dentin, predentin, odonbtoblastic layer, pulp, or a combination of these sites.

C-fibers ·     Most responsive to pulp-damaging stimuli, heat, or inflammatory agents.

·     Responsible for intense aching pain. The high threshold of C-fibers may make them resistant to dentinal hydrodynamic stimulation.

A-beta non-nociceptive low-threshold mechanoreceptors ·     Conduct signals due to vibratory stimuli.
Mostly unmyelinated fibers that contain neuropeptides ·     Neuropeptides include – substance P, calcitonin gene-related peptide (CGRP), and neurokinins.

·     These fibers end in pulp and dentin.

[From: Inoki R, Kudo T, Olgart LM. Dynamic aspects of dental pulp. Cambridge, Great Britain: Chapman and Hall. 1990].

 

FIBER TYPE MYELIN ENDS IN CONDUCTION VELOCITY STIMULUS THRESHOLD RESPONDS TO RESPONSE (Patient’s symptoms)
A-beta Yes Pulp-dentin border Fast

[40-70 m/s]

Low Air drying & Probing (exposed dentin); Cold (not heat). Hypersensitivity/ Sharp pain
A-delta Lightly Pulp periphery Slow

[5-15 m/s]

Low Air drying & Probing (exposed dentin); Thermal change. Hypersensitivity/ Sharp pain
Silent A-delta Lightly Pulp periphery Slow Low Intense heat/cold reaching pulp proper. No response unless activated
C

(poly-modal)

No Pulp core Slowest

[0.5-1 m/s]

High Histamine & Bradykinin (exposed pulp); Thermal; Mechanical. Dull pain

[From: Seltzer & Bender’s Dental Pulp].

 

Leave a Reply