Evaluation of an electronic device for gingival fluid quantitation.

A number of factors which might affect the readings of the HAR-600 GCFM were studied: 1. The readings were higher when the filter paper strips were placed between the fron halves of the upper and lower counterparts than when they were placed between the rear halves. No differences in readings were observed when the strips were placed in the middle, the left, or the right areas of the counterparts. 2. The higher the fluid viscosity the lower the reading. Salt water (0.9% NaCl) gave a lower reading than deionized water. 3. Increased room temperature or relative humidity led to higher readings, especially when the fluid volume exceeded 0.2 microliter. 4. More reading time was required for high viscosity fluid, low temperature, and high relative humidity. The HAR-600 GCFM readings and the lengths of ninhydrin-stained areas were compared. Both methods were able to reflect the amounts of serum absorbed.