Diagnostic characteristics of crevicular fluid aspartate aminotransferase (AST) levels associated with periodontal disease activity.

During a 2-year period pocket depth, probing attachment level, gingival index, and crevicular fluid aspartate aminotransferase (AST) levels were monitored in 25 previously treated periodontitis patients. Probing attachment level change was used retrospectively to identify sites where active periodontal destruction had occurred. The ability of crevicular fluid AST activities at 600, 800, 1000, and 1200 microIU levels to recognize active disease was investigated. Probing attachment level changes observed support the concept that the pattern of periodontal disease activity is episodic and infrequent. A loss of greater than or equal to 2 mm was found at 11% of all studied sites, whereas a gain of greater than or equal to 2 mm was noticed for 15% of sites. 2 subjects had 3 teeth that lost greater than or equal to 2 mm of attachment, whereas 15 subjects demonstrated no teeth with disease activity. The remaining 8 subjects had 1 or 2 sites that lost greater than or equal to 2 mm of attachment. Bayes's theorem and ROC curves were used to exemplify the sensitivity and the specificity of AST assessments. The AST 800 microIU demonstrated a sensitivity of 0.93 and specificity 0.68 and an odds ratio of 15.4 for attachment loss greater than or equal to 2 mm. Under the conditional probability of either 50%, 25% or 10% active disease prevalence, AST 800 microIU has a predictability of 73%, 50% and 24% respectively.