Regional variability in the permeability of human dentine.

This was measured qualitatively by using dyes and quantitatively by hydraulic conductance in dentine discs and crown segments in vitro. Both types of preparation demonstrated large regional differences in permeability, with the highest values at the periphery and the lowest in the centre of the disc or crown. As dentine permeability may vary 3-10-fold across a few millimetres, investigators should use as large a surface area as possible to compensate for these regional differences.