Extracellular potassium concentrations in human dental plaque fluid recovered from single sites.

Previous studies using potassium ion-selective microelectrodes have demonstrated that potassium concentrations in dental plaque fluid obtained by centrifugation are identical to whole plaque values determined immediately after collection. Such procedures were now used to examine the variations in potassium concentrations between single-site samples of overnight-fasted resting plaque fluid. The potassium concentrations (67.3 +/- 10.8 mmol/l, N = 50) were similar to those found before in whole plaque within 1 min of removal from the mouth and did not appear to be site-dependent. Possible mechanisms for the maintenance of potassium in plaque fluid at higher than salivary levels are described.