Necrotizing gingivostomatitis is an inflammatory condition affecting the gingiva and mouth that is caused by fusiform bacteria and spirochetes. It is characterized by painful, red gingiva with crater-like sores between teeth, bleeding gums, bad breath, and fever. Examination of affected tissue shows many bacteria and white blood cells. Histologically, there is gingival ulceration and necrosis with an inflammatory cell infiltrate. Treatment involves cleaning the mouth with antiseptics followed by scaling and antibiotics to resolve the infection.