Journal of Dental Research, Vol 65, 448-451, Copyright © 1986 by International & American Associations for Dental Research Online Journals
Characterization of human dental plaque formed on hydrogen-ion-sensitive field-effect transistor electrodes
R. Chida, K. Igarashi, K. Kamiyama, E. Hoshino and M. Esashi
The purpose of this study was to evaluate (with scanning electron
microscopy and microbiological characterization) the bacterial deposits
which accumulate on hydrogen-ion-sensitive field-effect transistor
electrodes (pH-ISFET) under conditions normally employed for telemetric
monitoring of changes in human dental plaque pH. Electrodes were mounted in
a carrier appliance which was worn for two, four, and six days. The plaque
pH response to a sucrose solution increased with the age of the plaque, as
expected from previous studies. After two days, the electrode was shown to
be almost completely covered with cocci. At days 4 and 6 there was a
dramatic increase in the number of rods present in the plaque. Adjacent
enamel surfaces showed similar accumulations of bacteria. The total number
of bacteria which had accumulated per unit area by day 4 was very similar
for the electrode and enamel surfaces. On both surfaces the plaque
contained approximately 25% streptococci, and the dominant species was
Streptococcus sanguis (approximately 75%). The plaque which accumulated on
pH-ISFET electrodes could not be distinguished visually or
microbiologically from that which formed on control enamel surfaces.
