Dentine hypersensitivity: the measurement in vitro of streaming potentials with fluid flow across dentine and hydroxyapatite.
Stimulus transmission across dentine, in conditions such as dentine hypersensitivity, is considered to occur via a hydrodynamic mechanism. This fluid flow in dentine may then induce a mechanoreceptor response in pulpal nerves. However, when fluid flows through a porous structure electrical potentials are also generated. The aim of this study was to develop a reproducible model system to measure streaming potential across dentine and hydroxyapatite and determine the influence of pressure. Using an acrylic cell, with silver electrodes, streaming potentials were recorded across dimensionally standardized dentine and hydroxyapatite specimens, over a pressure range of 1-6 atmospheres. Streaming potentials were found to be directly proportional to pressure and dependent on the electrical conductivity of the saline used in the cell. The results confirm the limited existing data on streaming potentials across dentine and indicate that at these low pressures excitation of pulpal nerves would not occur. However, if, as may be the case, stimuli applied to dentine create very high pressures, the resultant potentials generated could indeed evoke a neural response. The model system is worthy of further use to study this phenomenon and the factors which may influence it.
Department of Medical Physics, University of Wales College of Medicine, Cardiff, United Kingdom.
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Griffiths
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Morgan
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Williams
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Addy
D003804:Dentin / Q000502:physiology*; D003807:Dentin Sensitivity / Q000503:physiopathology*; D017886:Durapatite; D004553:Electric Conductivity; D006882:Hydroxyapatites; D008564:Membrane Potentials; D008954:Models, Biological; D008961:Models, Structural; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D012212:Rheology
D006882:Hydroxyapatites; D017886:Durapatite