The purpose of this study was to determine the correlations between various clinical assessments of inflammatory periodontal disease and the percentage of motile bacteria in the subgingival flora of sites representing widely varying states of periodontal disease. Darkfield microscopy was used to determine the percentage of spirochetes and other motile bacteria at two sites from each of 60 volunteers. For each site the following clinical assessments were recorded: Plaque Index (PII), gingival exudate (GE), Gingival Index (GI), bleeding tendency (BT), pocket depth (PD), connective tissue attachment loss (AL) and Periodontal Disease Index (PDI). Statistically significant (P less than 0.001) positive correlations (r) were found between the percentage of subgingival spirochetes and PII (r=0.54), GE (r=0.61), GI (r=0.57), BT (r=0.59), PD (r=0.56), AL (r=0.56) and PDI (r=0.61). Clinically healthy sites harbored much lower percentages of motile bacteria than did clinically disease sites. Most of the observed variation in the percentage of motile bacteria could be accounted for by variations in the percentage of spirochetes. The most significant increases in the relative percentages of subgingival spirochetes occurred when bleeding upon probing was observed as a sign of inflammation and/or when pocket depth and attachment loss exceeded 3 mm.

To determine the sensitivity and specificity of the radiographic detection of calculus, 275 proximal tooth surfaces from 18 patients were evaluated. Standardized periapical radiographs obtained before extraction were coded, batch processed, and evaluated independently by two investigators under optimum viewing conditions. After extraction, the teeth were photographed and evaluated both microscopically and by planimetry on 40 X linear projections. Evaluation of calculus by conventional radiography showed low sensitivity: radiographic deposits were detected on only 44% of surfaces that demonstrated calculus microscopically. Specificity was high and the rate of false positives was only 7.5%. Detection of calculus was influenced by the thickness of calculus, the percentage of root surface occupied by calculus, and by tooth type; but not by attachment loss, probing depth, proximal surface, or arch location. These results show that present radiographic techniques are not appropriate for detecting calculus on root surfaces.