Periodontal pocket measurements with a modified Plast-o-Probe and a metal probe.

Two types of periodontal probes used to measure pocket depths, i.e. a modified Plast-o-Probe (PoP) and a metal probe (MP), were compared. Periodontal pocket depths in 5 volunteers were determined by 5 clinically trained investigators using each of the probes. The average periodontal pocket depth was found to be the same for both probes and was independent of the degree of gingival inflammation and the localisation of probing. The results obtained by 1 of the 5 investigators were influenced by the type of probe. 4 investigators found that PoP permitted a 2.8-11.0% greater degree of reproducibility while MP exhibited a 0.9-12.2% higher inter-investigator agreement. In vivo and in vitro radiological and histometrical analysis on another group of patients showed a similar degree of penetration into the connective tissue zones with both probes. The investigators considered PoP a precise instrument but suggested that its readability should be improved for routine clinical use.