Afferent impulses from the teeth due to pressure and noxious stimulation

The earliest workers, Hunter & Charles Bell [1811], believed that the dentine was insensitive to pain and that its apparent response to stimuli was due to mechanical impulses which were transmitted to the pulp. Clinical observations by Duval [1833] and Thomas Bell [1835] showed that the dentine itself was acutely sensitive to pain. This has been the generally accepted view up to the present time. Peaselee [1857] mentions that various forms of pressure can be detected and to some extent localized by the teeth. Friinkel [1871] pointed out that this power of localization was due to the nerves of the periodontal membrane and was still present after removal of the pulp. Black [1887] clearly recognized that both the pulp and periodontal nerves were necessary to complete the sensory complex of the tooth. The nerves of the periodontal membrane responded to the slightest pressure, whereas the pulp nerves gave rise to pain whatever the stimulus. The demonstration by Stewart [1927] that the tactile thresholds of teeth were practically unchanged after extirpation of the pulp strongly suggests that the tactile sensitivity is limited to the periodontal membrane, although it has been maintained that there is a considerable amount of tactile sensibility over and above pressure which is affected by removal of the pulp [Woods, 1914]. Others have suggested that alterations in the calibre of the dentinal tubules from occlusive stress may be transmitted to the pulp nerves [Sprenkel, 1936]. At the present time, it is most generally accepted that pain is related to the pulp fibres and touch to the periodontal membrane, although pain may arise from this region as well.