Microscopic evaluation of clinical measurements of connective tissue attachment levels

The purpose of this study was to determine how accurately periodontal probes measure connective tissue attachment levels in beagle dogs with (1) clinically healthy gingivae, (2) experimental gingivitis, and (3) periodontitis. In the healthy and experimental gingivitis specimens the probes were inserted with a standardized force of 25 ponds. In periodontitis specimens the probes were inserted with a gentle, but nonstandardized force. After insertion, 120 plastic periodontal probes (40 in each group) were held in place by fusing them to the teeth. Blocks of periodontal tissue with the probes in situ were subsequently processed and serially sectioned. Histometric measurements were made from the sections in order to compare the level of connective tissue attachment to the level of probe penetration. In healthy specimens the probes consistently failed to reach the apical termination of the junctional epithelium (x = -0.39 mm). In the experimental gingivitis group most probes came closer to the apical termination of the junctional epithelium, but on the average still fell short by x = -0.10 mm. In periodontitis specimens the probes consistently went past the most apical cells of the junctional epithelium (x = +0.24 mm). A significant relationship between the degree of inflammation and level of probe penetration was found. No relationship was observed between histological and clinical sulcus depths. It is concluded that in beagle dogs (1) periodontal probes do not precisely measure connective tissue attachment levels, (2) inflammation has a significant influence on the degree of probe penetration, and (3) histological and clinical sulcus depths differ significantly.