Pathway 13-7-5 DETECTION First Step - PLASTICITY OF INTRADENTAL NERVE FIBERS （neuro imflammataion）
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Questions and Answers

What role do voltage-gated sodium channels play in the neural response to inflammation in dental pulp?

  • They alter the firing characteristics of nociceptors in inflamed tissues. (correct)
  • They completely inhibit neuronal activity in inflamed tissues.
  • They are responsible for enhancing nerve regeneration.
  • They exclusively increase pain sensitivity by degrading pain pathways.

    • Which sodium channel expression is notably increased in inflamed dental pulp collected from patients with irreversible pulpitis?

  • Nav 1.8 and Nav 1.9 (correct)
  • Nav 1.7
  • Nav 1.2
  • Nav 1.4

    • What could explain the difficulty in achieving profound anesthesia in inflamed tissues?

  • Resistance of TTX-R sodium channels to lidocaine. (correct)
  • Decreased density of nerve fibers in inflamed areas.
  • Higher local pH levels affecting drug ionization.
  • Increased blood flow that enhances lidocaine metabolism.

    • How do denervated teeth compare to innervated teeth in terms of healing after pulp exposure?

    <p>Innervated teeth demonstrate superior healing owing to neurogenic inflammation.</p> Signup and view all the answers

    What effect does PGE2 have on neurons isolated from dorsal root ganglia cells?

    <p>It increases TTX-resistant sodium channel currents rapidly.</p> Signup and view all the answers

    What role do neurotrophic factors play in the innervation of teeth?

    <p>They regulate neuronal structure, survival, and function.</p> Signup and view all the answers

    ⭐️⭐️Which neurotrophic factor is suggested to support neurons responsible for nociception?

    <p>Nerve growth factor (NGF)</p> Signup and view all the answers

    What happens to the number of nerve fiber sprouts when inflammation subsides?

    <p>It decreases.</p> Signup and view all the answers

    ⭐️Which cells synthesize NGF in the dental pulp?

    <p>Fibroblasts</p> Signup and view all the answers

    What is the primary function of the large trigeminal neurons in adult teeth?

    <p>Transmitting mechanosensitive stimuli</p> Signup and view all the answers

    ⭐️What is the primary receptor for NGF on the axonal surface of sensory fibers?

    <p>TrkA (tropomyosin receptor kinase A)</p> Signup and view all the answers

    Which nerve fibers sprout into inflamed tissues surrounding pulpal injury in rats?

    <p>CGRP and SP-containing fibers</p> Signup and view all the answers

    Study Notes

    Tooth Innervation

    • The innervation of teeth is dynamic and influenced by aging, injury, and dental caries.
    • Nerve fibers sprout into inflamed tissues surrounding pulpal injury, increasing CGRP and SP content.
    • Sprouting decreases when inflammation subsides.
    • Neuron growth factors govern the innervation pattern in normal and inflamed teeth.
    • NGF and GDNF play crucial roles in maintaining neuronal structure, survival, and function.
    • During development, all dental fibers require NGF and express its receptor, TrkA.
    • In adult teeth, larger trigeminal neurons depend on GDNF, while smaller neurons rely on NGF.
    • GDNF supports neurons responsible for mechanosensitive stimuli, while NGF supports nociception.
    • NGF binds to TrkA receptors, leading to internalization and transport to the cell body.
    • NGF expression regulates neural changes during inflammation.
    • NGF receptors are found on intradental sensory fibers and Schwann cells.
    • NGF is synthesized by fibroblasts in the coronal subodontoblastic zone.
    • Increased NGF production corresponds to areas of the pulp with maximum sprouting of CGRP- and SP-containing nerve fibers.
    • Neuroimmune interactions occur in the dental pulp, with a coordinated increase of pulpal nerves and immune cells.
    • Recruitment of immunocompetent cells occurs after electrical tooth stimulation.
    • Similar responses are seen in periapical bone with radicular pulpitis.
    • Neurogenic inflammation enhances healing, as denervated teeth heal poorly.

    Voltage-Gated Sodium Channels

    • Changes in the distribution and activity of voltage-gated sodium channels occur during neural response to inflammation.
    • Mice lacking the Nav 1.7 gene show reduced pain-like behaviors when exposed to proinflammatory agents.
    • TTX-resistant sodium channels (Nav 1.8 and Nav 1.9) are increased in inflamed dental pulp.
    • Exposure to PGE2 increases TTX-resistant sodium channel currents, indicating increased activation of existing channels.
    • These sodium channels are relatively resistant to lidocaine, explaining difficulty in achieving profound anesthesia in inflamed tissues.

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