Periodontitis is a disease characterized by loss of connective tissue attachment and bone around the teeth in conjunction with the formation of periodontal pockets due to the apical migration of the junctional epithelium.Early diagnosis and treatment of progressive periodontitis is important because of the irreversible nature of this disease. Traditional clinical measurements used for periodontal diagnosis are often of limited usefulness in that they are indicators of previous periodontal disease rather than present disease activity. There is a need for development of new diagnostic tests that can detect the presence of active disease, predict future disease progression and evaluate the response to periodontal therapy, thereby improving the clinical management of periodontal patients. This book discusses the role of oral bio-markers in the diagnosis and progression of periodontal disease and describes the role of GCF β-Glucuronidase levels as a diagnostic tool and measure of treatment outcome in patients with chronic periodontitis.