A cross-sectional analysis of aspartate aminotransferase in human gingival crevicular fluid

Previous investigation has shown that the concentration of aspartate aminotransferase (AST), an established serum marker for cardiac and liver damage in humans, is significantly elevated in samples of gingival crevicular fluid (GCF) from ligated teeth in beagle dogs. This paper reports on a cross-sectional study of the relationships between AST in GCF and clinical indices of human periodontal disease in 60 patients with mild to moderate adult periodontitis. AST standardized to a 30-second collection interval (AST30) showed substantial (multiple regression R2 = 0.61) association with summary indices of patient disease status, modest association (partial R2 = 0.22) with tooth disease status within patient, and weaker (partial R2 = 0.12) but statistically significant association with site-to-site variation in disease at the same tooth. AST concentration showed modest (R2 = 0.30) between-patient relationship with clinical indices, but no clinically significant relationship with these indices between sites within patients, suggesting a rough proportionality between accumulated enzyme and GCF volume at sites with varying stages of disease. The relationship between GCF volume and probing depth also appears central to interpretation of enzyme assays. Clinical measures of past periodontitis and current inflammatory disease are cross-sectionally related to variation in AST30, across patients and sites within the same patient. Considerable residual variation, especially elevated AST30 in the absence of clear signs of disease, may result from varying levels of current disease activity, not reflected in clinical measures.