['Epidemiologic studies suggest a relationship between periodontitis and liver diseases. A rat periodontitis model was used to investigate whether a causal relationship exists between periodontitis and liver diseases.', 'Fourteen male Wistar rats (8 weeks old) were divided into two groups: a periodontitis group in which Escherichia coli lipopolysaccharide (LPS) and Streptomyces griseus proteases were applied into the gingival sulcus for 8 weeks, and a control group using pyrogen-free water instead. After blood samples were collected, periodontal tissues and liver specimens were analyzed.', 'Chronic administration of LPS and proteases to the gingival sulcus induced periodontitis and liver injury, including steatosis with inflammation and sinusoidal fibrosis. Apoptosis, enhanced concentration of 8-hydroxydeoxyguanosine, and activated production of tumor necrosis factor-alpha in liver were observed in the periodontitis group, with increased gingival inflammation, serum LPS, and reactive oxygen species.'] Does chronic administration of lipopolysaccharide and proteases induce periodontal inflammation and hepatic steatosis in rats?