Relationship between crevicular aspartate aminotransferase levels and periodontal disease progression

Background: Aspartate aminotransferase (AST), an enzyme released from necro tic cells, has been identified in gingival crevicular fluid (GCF), and elev ated levels are associated with periodontal tissue destruction. The aim of this study was to examine the relationship between elevated GCF levels of A ST and periodontal disease progression. Methods: Over a 12-month period, 8 to 10 interproximal sites in 41 periodon titis subjects (PS) and 15 healthy subjects (HS) were monitored. Clinical m easurements included relative attachment level (RAL), probing depth, and bl eeding on probing (BOP). Semiquantitative levels of GCF AST (<800 <mu>IU, g reater than or equal to 800 mu IU, and greater than or equal to1,200 mu IU) were determined using a chairside assay. At the 6- and 12-month visits, sc aling and foot planing and prophylaxis were performed in the PS and HS, res pectively. Sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) were calculated for 2 diagnostic criteria (AST greater than or equal to 800 mu IU, AST greater than or equal to1,200 mu IU) utilizing 4 thresholds of disease progression as determined by 2 met hods (absolute change in relative attachment level and cumulative sum [CUSU M]). Results: The percentage of sites exhibiting AST greater than or equal to 80 0 mu IU, AST greater than or equal to1,200 mu IU, and BOP in the PS was sig nificantly (P <0.02) lower at 6 and 12 months compared to baseline. The use of crevicular AST activity to monitor periodontal disease progression was associated with many false-positive results. Overall, low specificities, PP V, and odds ratios were demonstrated by the assay when using 2 diagnostic c riteria and 4 thresholds of disease progression. The high NPV suggest that a negative AST test result was indicative of a periodontally stable site. Conclusions: These results demonstrate that elevated levels of AST were pre sent at sites that did not subsequently exhibit disease progression. The hi gh prevalence of AST-positive sites due to gingival inflammation diminished the test's ability to discriminate between progressive and stable, but inf lamed, sites.