Experimental proof of the types of neurons that innervate the tooth pulp

That the tooth pulp is sensitive to pain and to temperature changes which are subjectively interpreted as pain, but apparently does not possess tactile end organs, is undisputed (Huber, '98; Allen, '25). Black ('87) has maintained that it requires both the pulp and the peridental membrane to complete the sum of the sensory functions of the tooth. Moreover, the nerves in the peridental membrane are stimulated by pressure, and this membrane thus acts as the touch organ of the tooth (Noyes, '15). Destruction of the tooth pulp should result in degenerative changes (chromatolysis) in the neurons which supply it. Should such destruction likewise affect the peridental membrane, the degeneration will not only involve neurons mediating painful impulses, but also those carrying the tactile ones. The presence of unmyelinated nerve fibers in the spinal nerves and their origin, course, and probable function seems to have been sufficiently established in a long series of reports by Ranson and his colleagues (Ranson, '08, '09, '11, '12, '13, "14 a, '14 b, '15; Ranson and von Hess, '15; Ranson and Billingsley, '16 ; Windle, '23). Such unmyelinated fibers arise from small cells in the spinal ganglia and outnumber the large cells approximately three to one (Ranson, '08). I n a classification based upon the size and distribution of Nissl bodies