Periodontal disease is a chronic inflammatory disease of the gums and tissues surrounding the teeth. It is caused by plaque bacteria, including Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans. Left untreated, it can lead to tooth loss. Symptoms include red, swollen, bleeding gums; bad breath; and loose teeth. It is diagnosed through examination of the gums and bone measurements. Treatment involves deep cleaning or surgery to remove bacterial infection. Daily brushing and flossing is the best prevention method.