Objective: To study the effects of smoking or diabetes on the level of aspartate aminotransferase in gingival cervical fluid (GCF-AST).Methods: Periodontal disease index(PDI) and GCF-AST were measured and compared in 105 smokers,86 patients with diabetes and 90 healthy controls.Results: The PDI values in smokers and diabetes patients were higher than that in controls (P