Significance of Pain Diagnosis

مجهول

• Many dental patients are in pain when they areseen. The most commo cause of pain in the orofacial region is inflammatory disease of either thepulp or the tooth's supporting structures. Effective
• Thus before a practitioner treats apatient in pain, a correct diagnosis is essential.
• Thus before a practitioner treats apatient in pain, a correct diagnosis is essential.
although most dental pain results from inflammatory changes,such inflammation of pulp and periradicular tissues is often not painful. In fact, pain severe enough for the patient to seek dental treatment
may occur only a small proportion of the time.

Pain Mechanisms
Specificity
• A longstanding belief is that a specific part of the
nervous system is responsible for carrying pain
from pain receptors to a pain center in the central
nervous system.
• There are, in fact, some nerve
fibers that respond only (or maximally) to stimuli
in the noxious range.
. However, the existence of such a dedicated "pain system" is not sufficient, in itself, to explain all experimental and clinical features of pain such as:Referred pain, trigeminal neuralgia as well as the clearly documented effects of emotional and motivational factors

Gating
• The anatomic substrate of the gating mechanism for pain is in the dorsal horn of the gray matter of the spinal cord and brainstem.
• The gate either inhibits or facilitates the activity of transmission cells that carry activity further along the nervous pathway.
• A number of factors determine whether the gate is open or not.
• One important factor is the relative degree of activity in large diameter AB fibers and small diameter A8 and C
fibers.
• . The large diameter AB fibers are activated by nonnoxious stimuli, and the small A8 and C fibers by noxious stimuli. Large fiber activity tends to close the gate, whereas small fiber activity opens the gate. Descending control mechanisms.


Pain as an Experience
This overall description of the processing of noxious
information integrates the presence of receptors
and pathways specialized to conduct pain.

The Versatility of Pain
• The characteristics of pain can change with time because of the adaptation of peripheral receptors, facilitation or fatigue among central connections, or a number of other causes..



• Persisting noxious input, particularly from C fibers, can produce changes in the dorsal horn neurons, especially
in the presence and distribution of membrane receptors."
The changes in these altered neurons can persist long after the original stimulus, a phenomenon known as central sensitization or "windup.""
These long-term changes in excitability can lead to spontaneous pain or decreased pain threshold and may be a component of some chronic pain syndromes


Superficial Versus Deep Pain
• Pulpal pain may be considered deep (visceral). Periradicular pain is superficial (peripheral
• Pain from deep tissues is poorly localized.

• In contrast, larger, faster nerve fibers in superficial tissues and less central convergence allow more precise localization of superficial pain. Pulpal pain may be considered deep
Thus extension of inflammation from a deep site (pulp) to a superficial one (periradicular tissues) often allows localization of the tooth that is
the culprit.