Journal of Dental Research, Vol 69, 1806-1811, Copyright © 1990 by International & American Associations for Dental Research Online Journals
Electrochemical impedance characterization of human and bovine enamel
M. Levinkind, T. J. Vandernoot and J. C. Elliott
London Hospital Medical College, United Kingdom.
The alternating current impedance characteristics of human and bovine
enamel slices were measured in vitro. An electrochemical cell containing
two platinum gauze electrodes and 0.01 mol/L KCl buffered to pH 7.4 at 20
degrees C was used. The electrodes were attached to a potentiostat that was
connected to a microcomputer-controlled frequency-response analyzer.
Measurements were made at discrete frequencies between 1 Hz and 65 kHz by
application of a sinusoidal potential of 50 mV (rms) across the assembled
cell. The impedance was calculated from the input potential and the
resulting measured flow of current. For quantitative evaluation of these
measurements, an equivalent circuit was postulated. It contained five
passive electronic components and accurately modeled the different
specimens. Values for individual electrical components in the equivalent
circuit were estimated by complex non-linear least-squares regression
analysis. This study demonstrated that it is possible to measure and
quantitatively distinguish between the impedance characteristics of:
permanent human, deciduous human, and bovine enamel, as well as the enamel
from a variety of sites from human teeth, some of which had been extracted
prior to being fully erupted. Proposals are made as to which physical
properties in the specimens are modeled by individual components in the
equivalent circuit.
