Congenital insensitivity to pain--review and report of a case with dental implications.

Pain is a protective mechanism for the body. Absence of pain is a symptom in several disorders, both congenital and acquired. The congenital types are present at birth and affect the number and distribution of types of nerve fibers. At present, 5 types of hereditary sensory and autonomic neuropathies have been identified. The various disorders within this group are classified according to the different patterns of sensory and autonomic dysfunction and peripheral neuropathy and the presence of additional clinical features such as learning disability. However, the field is currently moving away from classification based on clinical presentation toward classification based on underlying genetic abnormality. In the absence of pain, patients are at risk of late presentation with illnesses or injuries, and have an increased incidence of traumatic injury. Self-mutilation is an almost invariable feature of these disorders. We report the case of a patient with congenital insensitivity to pain that presented with self-mutilation injuries to his hands and oral tissues caused by biting. The severe nature of these injuries necessitated serial extraction of his primary teeth soon after eruption, which led to a cessation of the problem. The mutilation has not returned following the eruption of the first of his permanent teeth, suggesting that he has learned not to bite himself, even though to do so causes him no discomfort.