This paper describes the use of micro-electrodes for the analysis of small fluid volumes recovered from the oral environment. The analysis has several advantages: (1) It directly measures the activity of ions, a quantity more relevant to mineral saturation than the conventionally measured concentration, (2) minimum fluid volume for analysis is usually less than 0.005 μL, small enough to avoid sample pooling in most analyses, (3) numerous ions can be measured simultaneously, (4) the analysis time is very short, and (5) the use of mineral oil to isolate specimens provides a simple method for controlling the CO2 tension and humidity over the specimens.
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