In Vitro pH Response of a Periodontal Probe-type Antimony Micro-electrode

The pH of the periodontal pocket is related to the microbial flora and the inflammatory process in periodontal tissues. Many investigators have studied the pH in gingival crevices or periodontal pockets using different methods which have yielded a variety of results. In order to measure the pH directly in periodontal pockets, a periodontal probetype antimony micro-electrode (AT) was designed. The antimony electrode is not fragile and is thus convenient for pH recording, but it has been reported to be inaccurate in the presence of organic reducing agents. The purpose of this study was to evaluate the accuracy of the AT in comparison with a conventional glass electrode (GL) in vitro. The AT tip diameter was 0.5 mm, and its form and size were similar to those of the conventional periodontal probe. Prior to the pH measurement, the AT was calibrated using standard buffers of pH 4 and 7, while the GL was calibrated with pH 4, 7 and 9 buffers. The two electrodes were put in the same test solution to give the pH readings simultaneously. Either HCl or NaOH was gradually added to the standard solutions to cover the pH range of 4.0-9.2, and the pHs given by the GL and the AT were continuously recorded. Then, the pH values of buffer solutions containing glucose (278 mmol/l) and/or blood (10%) were measured with both electrodes to see if there were any observable differences between them. As a result, the pH values given by AT and GL matched each other in the range of 4.0