Pain Irradiation

Pain irradiation (Latin: dolor irradians) is the process of the pain impulse spreading from the site of inflammation to other areas innervated by branches of a nerve. In dentistry, this phenomenon is most commonly observed in cases of irreversible pulpitis.

Etiology and pathophysiology

The mechanism of development is associated with the convergence of nerve pathways. Pain signals from different teeth and facial zones converge in the common nuclei of the trigeminal nerve in the brain. When intensely stimulated, the brain loses the ability to precisely localize the source, and it seems to the patient that the pain is emanating from a healthy tooth, ear, temple, or the entire half of the jaw.

Clinical significance

Pain irradiation is a classic sign of irreversible pulpitis and an important criterion for differentiating it from apical periodontitis. When the infection progresses beyond the tooth root into the periodontal apparatus, the irradiation typically disappears, allowing the pain to become well-localized, aiding in identifying the causative tooth.