Aside from the bacteria that cause gum disease, there are other considerations which can modify the course or aggressiveness of the disease. These are called "risk factors" and are Smoking, Diabetes, Genetically induced gum disease. In periodontal diseases, bacteria trigger inflammatory host responses which, along with the direct destructive effects of the bacteria, cause most of the tissue destruction. This book describes about the knowledge regarding the etiology and pathogenesis of various diseases and a quick review for undergraduate,post graduate&clinicians who can update their knowledge