EN
Periodontitis, an inflammation of periodontal tissues, exists in several clinical forms. The most common one is adult periodontitis with Porphyromonas gingivalis, a Gram-negative anaerobic rod, being generally regarded as the major pathogen involved in this disease. This organism produces a large quantity of proteolytic enzymes, as virulence factors, which are considered to play a crucial role in its pathogenecity. These enzymes are involved in both destruction of periodontal tissues and interrupting host-defence mechanisms through the degradation of immunoglobulins and complement factors leading eventually to disease progression.