Prevalence and Progression of Periodontitis in Ankylosing Spondylitis

Inclusion Criteria: * Age ≥ 18 years * Subjects giving informed written consent * In case of AS patients, subjects to meet the 1984 modified New York criteria for AS. * In case of controls, subjects without a history of inflammatory arthropathy Exclusion Criteria: * Subjects having received periodontitis treatment including scaling within 6 months before study participation. * Subjects with a history of taking antibiotics including prophylactic anti-tuberculosis agents within 3 months before study participation. * Subjects with a hitory of taking immuno-suppresives (methotrexate, leflunomide, tacrolimus, cyclosporin, or azathioprine) or any dose of glucocorticoids (oral or pareneral) within 3 months before study participation. * Subjects with a history of diabetes mellitus. * Subjects with aggressive periodontitis requiring open flap debriment at enrollment immediately. * Subjects with a hitory of clinical inflammatory bowel disease. * Subjects with active infection, which can make an influence on the levels of acute phase reactants. * Subjects with any other condition to render the patient unable to understand the scope of the study or preclude the patient from following the protocol in the physician's opinion.