Marking width, calibration from tip and tine diameter of periodontal probes

The present study comprises an investigation of 7 different probe types, representing currently-marketed major designs (WHO-CPITN, Williams, Michigan), as well as available calibration systems (engraved, etched and painted markings). Width of markings, accuracy of calibration from probe tip, and tine diameter at the tip and at specified points along the tine were assessed, using a stereomicroscope at a magnification of x 40. Blind duplicate measurements of these probe tine characteristics were 100% reproducible to within 0.01 mm. There was an overall range in marking width from 0.00-1.13 mm. The best marking, in that it had no appreciable width and the highest accuracy, was the discrete transition between normal and engraved parts of probes with engraved bands. Mean inaccuracies of different probe sets varied from 0.06 to 0.22 mm. Probes from the same batch from the same production line could differ by more than 0.5 mm in calibration. Mean tip diameter ranged from 0.28 to 0.70 mm. It was concluded that probe tine diameter and calibration should be considered in addition to other variables of periodontal probing. Standardisation of tine characteristics and avoidance of the use of different types or batches in a single study should enhance the accuracy and reproducibility of periodontal probe-dependent measurements.