THE ELECTRICAL-RESISTANCE OF ENAMEL-DENTIN CYLINDERS - INFLUENCE OF NACL CONTENT IN STORAGE SOLUTIONS

Objectives. To investigate the influence of different electrolyte conc entrations on the electrical resistance of sound human enamel-dentine cylinders in vitro. Methods: Forty cylinders of 3-mm diameter and 2-mm length were drilled from 40 extracted caries-free third molar teeth. For ease of handling the samples were fixed in Perspex discs by means of a cyanoacrylate-adhesive. An a.c. source (frequency 500 Hz, amplitu de 1 mu A) with a high internal resistance was applied. Only Ohm's res istance was measured. The resistance measurements on the samples were made after storage in distilled water, 0.16 mM NaCl, 1.6 mM NaCl, 16 m M NaCl and 160 mM NaCl for 24 h. Results. The mean resistance values w ere 2026 +/- 152, 1835 +/- 178, 1605 +/- 364, 483 +/- 265 and 60 +/- 3 3 k Ohm, respectively. All values were statistically significantly dif ferent (Wilcoxon test; P<0.0001). Conclusion. It is concluded that the choice of electrolyte solution influences the resistance values of th e enamel-dentine samples. This effect should be taken into account whe n measuring electrical resistances in vivo and in vitro. (C) 1998 Else vier Science Ltd. All rights reserved.