Objectives: To compare the permeability of human dentin and a porous ceramic with two different compositions of perfusion fluid, in vitro. Methods: Dentin discs were cut from extracted third molar at a level close to the pulp chamber and ceramic discs were cut from a porous ceramic block. The convective permeability of the discs was measured in a fluid transport model using de-ionised water or 1:3 diluted bovine serum and the hydraulic conductance was determined. Results: In the negative controls, no flow was detected. The hydraulic conductance values for the dentin discs and the ceramic discs when water was used as the perfusion fluid were 0.069±0.023and 0.047±0.019ml min-1 cm-2 cm H2O-1, respectively. When the discs were perfused with the diluted bovine serum the mean (standard error of the mean) hydraulic conductance values for the dentin and the ceramic discs were 0.036±0.016 and 0.012±0.0055 ml min-1 cm-2 cm H2O-1, respectively. Conclusion: Basing on the modern technique it is possible to fabricate discs of hydroxylapatite ceramic to act as substitutes for dentin barriers in cytotoxicity test.