inflammation of the gums (gingivae). Symptoms include tender, sometimes swollen, gums that bleed easily. Areas of tissue destruction (necrosis) or ulceration may develop, and fever and halitosis may be present in severe disease. The most common cause of gingivitis is the accumulation of dental plaque on exposed tooth surfaces. The form of gingivitis known as trench mouth (Vincent's gingivitis (Vincent gingivitis)) is believed to be caused by a spirochete, Borrelia, and a bacterium, Fusobacterium, acting in symbiosis on previously weakened gum tissue. General infections, poor tooth alignment (malocclusion), poor dental hygiene, and faulty dentures are other causes of gingivitis. In some cases, gingivitis occurs as a result of another disease, such as diabetes mellitus, leukemia or similar blood dyscrasias, or vitamin deficiency.

Herpes simplex virus causes an infectious, painful gingivostomatitis, characterized by the development of white plaques and vesicles in the mouth.