The mechanisms of reception and transmission of sensitivity through the dentine have been the subject of numerous controversies. Several theories have attempted to explain the enigma of the sensitivity of this tissue, that appear to be so poor in nerve fibers and sensitivity receptors. This article discuss the data regarding the neurophysiology of the pulp-dentin complex and the odontoblast functions. The theory of direct stimulation of nerve fibers, the theory of dentinal receptors, the hydrodynamic theory and the theory of direct ionic diffusion are presented and analyzed. Each of these hypotheses fails to elucidate the mechanisms involved. The limitations of available techniques for investigation, the difficulties of isolation of the specific dentinal receptor and the lack of specific sensations (any type of stimulus elicits a painful response) complicate the understanding of the mechanisms involved in reception and transmission of stimulus through the dentin. Although the hydrodynamic theory appears to be the most commonly accepted, recent studies suggest that other neurophysiologic mechanisms could be also involved in reception and transmission of pain. Far from being clear, this problem needs a new approach, sophisticated research methods and more complex theoretical and experimental simulations.
Keywords:- DENTINE SENSITIVITY
- NERVE ENDING
- ODONTOBLAST
- STIMULUS