Peptidergic nerves in human tooth pulp

Substance P-like and enkephalin-like immunoreactive nerve fibers were observed in the human tooth pulp. Immunoreactivity for substance P could be demonstrated in thin, beaded nerve fibers and glomerular-type nerve structures both in the center and in more peripheral parts of the tooth pulp. Substance P-like nerve fibers predominated in the center of the pulp substance, while a thicker type of enkephalin-like nerve fibers were more commonly seen at the periphery of the pulp. Controls exhibited no immunoreactivity for either neuropeptide. It is tentatively suggested that a dual innervation by substance P-like fibers and enkephalin-like nerve fibers may be involved in the mediation of toothache in man.