Fig. 1.

Schematic of the apparatus used to measure dentin permeability. N₂ gas passed into a pressure vessel containing a beaker of water. The water passes through the system at whatever pressure is used. The rate of movement of a tiny air bubble in a 25 µL micropipette quantitates how much water permeates across exposed dentin. The microsyringe adjusts the position of the air bubble for the next trial (from Pashley et al.¹¹, with permission).