[pH determination in human crevicular fluids. Examination of the pH meter and evaluation of the correlation between pH level and clinical findings or the microflora in each periodontal pocket].

The purpose of this study was to investigate the accuracy and reproduction of a microelectrode with a glass capillary, and to discuss the correlation between the pH level and the microflora in periodontal pockets or the clinical findings in the various stages of periodontal disease. The upper or lower anterior teeth of 34 patients with mild to severe periodontal disease were examined. Before the measurement, supragingival plaque was removed from each tooth. A special glass capillary was incorporated in the microelectrode to cover its tip, so that it would not touch the pocket walls or tooth surfaces during pH measurement. After the pH in the crevicular fluid was determined, subgingival plaque was collected with paper points from each periodontal pocket. This bacterial plaque was sonicated with saline solution, and examined under a phase contrast microscope with a calibrated eyepiece graticule to count and morphotype groupings of microorganisms as 1) coccoid forms, 2) rods, 3) filaments, 4) motile rods, 5) spirochetes or other cell types. Crevicular fluid flow measurements and clinical findings (pocket depth, and gingival inflammation) were also investigated. The following conclusions were drawn: The electrode with capillary was useful to determine the pH of the crevicular fluid clinically. A reduction in pH level was seen in deep pockets or severe gingival inflammation. A close correlation was seen between salivary and crevicular pH. The pH level was significantly positively related with the proportion of coccoid forms, but was negatively correlated with the proportion of motile organisms that are reported to be related with periodontal disease.