The periotron gingival crevicular fluid meter

The present study was undertaken to compare the calibration curve of the periotron* (HAR‐6000) with those of two earlier models (HAR‐600) instrument, which was found to be appreciably more sensitive in detecting small volumes of fluid than the two older models, is curvilinear in shae while the latter two models display linear calibration characteristics Calibration curves were also obtained for one of the HAR‐600 models with the periopaper strip inserted up to and beyond the manufactures recommendations. The results obtained in this case differed from those published by others. Using fluids possessing different dielectric dissipation constants, calibration curves were determined for the HAR‐6000 model over a wide range of volumes, The calibration data obtained best fitted quadratic functions and the relative positions of the curves on the axes are in the correct relationship to their dielectric constants Inter‐instrument and other variations have once more stressed the importance of individual instrument calibration by uers.