Dental pain

Dr. 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

Primary afferent neurons: located in dorsal root ganglia Dorsal Horn – Prim. afferent neuron synapse

with 2nd order neuron 2nd order neuron

crosses midline and ascends to reach thalamus. Synapse in thalamic nuclei with 3rd neuron.

3rd order neuron send projections to internal capsule, and to

postcentral gyrus of cerebral cortex

Pain Pathways Lateral spinothalamic tract:

carries discriminative aspects of pain (location, intensity and duration)

Medial spinothalamic tract mediate autonomic and unpleasant emotional

perceptions of pain and project to thalamus

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 brain The system present in

Gray matter surrounding aqueduct of sylvius Raphe Magnus nucleus in pons

Neurotransmitters: Serotonin & Opiate receptor substances (Endorphin, Enjephalin

& Dynorphin)

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.