The repeatability of human dentine permeability measurement in vitro

OBJECTIVE: The aim of this study was to determine the repeatability of apparatus designed to assess dentine permeability at two different pressures. METHOD: Forty-five human coronal tooth portions were prepared and permeability was measured at two separate time points, 5h apart, at 14 cm H2O pressure and then at 100 cm H2O pressure. Repeatability was determined using the limits of agreement (LOA) method. RESULTS: The results showed equal mean permeability of 0.6 microl at both time 1 and time 2 at 14 cm H2O pressure, and 2.7 and 2.5 microl at time 1 and time 2, respectively, at 100 cm H2O pressure. At 14 cm H2O pressure, the LOA were (-0.4, 0.4)microl and at 100 cm H2O pressure the LOA were (-0.2, 0.6)microl. CONCLUSION: Although repeatability measurement at 14 cm H2O pressure appeared to be acceptable, the higher permeability values at 100 cm H2O pressure may make the latter the pressure of choice despite the small bias.