Dental Pain Pathway and Mechanism

download Dental Pain Pathway and Mechanism

of 19

  • date post

  • Category


  • view

  • download


Embed Size (px)

Transcript of Dental Pain Pathway and Mechanism

Dental painDr. MUMENA C.H

Key questions

What is pain? What are the components of pain? What is the pathway of pain sensation? What is referred pain? What are the pain control system in brain, spinal cord? How is dental pain stimulated? What is the mechanism of dental pain transmission?

What is pain?

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Nociception is used to describe the neural response to traumatic or noxious stimuli

Classification of pain

Clinical :

acute pain primarily due to nociception

chronic pain due to nociception but psychological and behavioural factors play an important role Pathophysiology:

Nociceptive pain: caused by activation or sensitisation of peripheral nociceptors, specialised receptors that transduce noxious stimuli Neuropathic pain: caused by the injury or acquired abnormalities of the peripheral or central neural structures.

What are the components of pain?

2 components

First pain

fast sharp, well localised sensation conducted by A fibres (pinprick)

Second Pain-(Slow pain)

Dull, slower onset, and poorly localised sensation conducted by C fibres

What is the pathway of pain sensation?

Pain Pathways

3 neuron pathways

Transmit noxious stimuli from periphery to cerebral cortex located in dorsal root ganglia Dorsal Horn Prim. afferent neuron synapse with 2nd order neuron crosses midline and ascends to reach thalamus. Synapse in thalamic nuclei with 3rd neuron. send projections to internal capsule, and to postcentral gyrus of cerebral cortex

Primary afferent neurons:

2nd order neuron

3rd order neuron

Pain Pathways

Lateral spinothalamic tract:

carries discriminative aspects of pain (location, intensity and duration) mediate autonomic and unpleasant emotional perceptions of pain and project to thalamus

Medial spinothalamic tract

What is referred pain?

Pain sensation produced in some parts of the body and felt in other structures away from the place of development N.B: superficial pain are not referred except deep and visceral pain

What are the pain control system in brain, spinal cord?

Brain control: Role:

block pain impulses before entering the brainGray matter surrounding aqueduct of sylvius Raphe Magnus nucleus in pons Serotonin & Opiate receptor substances (Endorphin, Enjephalin & Dynorphin)

The system present in


Spinal cord control

Posterior gray horn

Gateway for pain impulses to reach brain via spinothalamic tracts Gate Theory (Read)

Applied physiology: Analgesia: Loss of pain sensation Hyperalgesia: Increased sensitivity to pain sensation Paralgesia: abnormal pain sensation

How is dental pain stimulated?

Large nerve enter the apical canal of teeth Nerve trunks traverse the radicular pulp proceed to

coronal pulp and branch paripherally

Subodontoblastic plexus obvious apparent in the roof, lateral walls & lesser extent at root canals Network comprises myelinated and non-myelinated axons (Known as parietal layer of nerves or nerve plexus of Raschkow)

How is dental pain stimulated?

Most pulp nerve endings are in odontogenic region of pulp horns Some terminate on or in associations with odontoblasts Pain in tooth is a function of the high concentration of nerve endings within the tooth Pulp highly sensitive to temperature changes, electrical and chemical stimuli and pressure

What is the mechanism of dental pain transmission?

Teeth perceive only modality of pain. Theory explaining pain in tooth:

Direct innervation theory Transduction theory Hydrodynamic theory

Direct innervation theory

Based on belief that nerves extend to the DEJ. However studies no nerves present at this junction

Transduction theory

Odontoblastic process is a receptor It conducts the pain to nerve endings in the peripheral pulp and in the dentinal tubules.

Hydrodynamic theory

Based on the premise that when dentin is stimulated, fluid and the odontoblastic process move within the tubules, making contacts with the nerve endings in the inner dentin and adjust pulp. When nerve endings are contacted, they deform and act as mechanoreceptors to produce an impulse Several factors support this theory such as cold, heat e.t.c.