222 MICROSCOPIC ANATOMY OF THE TEETH 



and trophic fibres would be distributed to the pulp and also 

 to the dentine which contains within the tube a protoplasmic 

 prolongation of the odontoblast cell, the maintenance of the 

 functions of which would probably require a nervous supply. 



Historical Review 



The question of the innervation of the dentine has long 

 been a matter of much controversy, the majority of observers 

 holding that sensation was conducted by the dentinal fibril, 

 while others thought it probable that true nerve fibres were 

 supplied to the dentine. 



For a long period it was considered that dentine is not 

 sensitive, and even such an eminent authority as John Hunter 

 was of this opinion. He says (13) : ' We may presume 

 that the bony substance' (of the teeth) 'itself is not capable 

 of conveying sensations to the mind, because it is worn 

 down in mastication and occasionally worked on by operators 

 in living bodies without giving any sensation of pain in the 

 part itself.' Duval showed, in a paper which he read before 

 the Academy of Medicine in Paris in 1831, that there is 

 sensation in the dentine, and was of opinion that it is 

 chiefly manifested just beneath the enamel (5). 



Salter, in his classical work on Dental Pathology, writing 

 in 1874, says : ' The nerves of the tooth-pulp form loops 

 towards the periphery which may be readily demonstrated 

 by the action of caustic alkali, and from these, according to 

 Boll, large numbers of very minute fibrils proceed outwards 

 between the ivory cells and their tubular prolongations. 

 It is highly probable that these are the nervous elements 

 distributed to the dentine, but whether they pass into the 

 intertubular substance, or, fastening upon the tube walls, 

 are so piloted into the ivory structure, is quite uncertain. 

 It is, however, highly improbable that they pierce the wall 

 of the ivory cell and occupy the axes of the tubes ' (29). 



Boll's observations were made in 1868 (2), on the teeth 

 of Rodents, which he treated with a very weak solution of 

 chromic acid (~ to ~ P er cent.). His preparations showed 

 fine fibres in great abundance, which passed between the 

 odontoblasts, and where the dentinal fibril was pulled out 



