Dentin Permeability: Effects of Temperature on Hydraulic Conductance

The rates of fluid movement across dentin discs, in vitro, were measured at 10, 20, 30, 40, and 50°C in unetched and acid-etched dentin. Increasing the temperature 40° (i.e., from 10 to 50°C) resulted in a 1.8-fold increase in fluid flow in unetched dentin, which was of a magnitude similar to the decrease in viscosity that occurred over the same temperature range. In acid-etched dentin, the 40°C temperature change produced more than a four-fold increase in fluid conductance, more than double that which could be accounted for by changes in viscosity. Analysis of the data suggests that this additional increment in hydraulic conductance is due to thermal expansion-induced increases in tubular diameter.