Delineation of somatic nerve endings in rat teeth by radioautography of axon-transported protein.

We have shown that there is extensive innervation of cusp pulp and dentin in rat molars. The dental nerves either end freely below the odontoblast layer or form gap junction endings on the odontobast cell body or along its dential process. The nerves are largely absent from response dentin, are found in contact with virtually all other odontoblasts at the tip of the cusps, are less frequent in intercuspal regions, and are absent from root dentin and odontoblast layers. The incisors were completely different from the molars, perhaps because they are continuously erupting teeth. The distribution of nerve endings in rat molars may be representative of that in teeth of other species, but the nerve endings should be mapped radioautographically for each type of tooth before generalizations can be made.