Necrotizing Ulcerative Gingivitis (NUG) is an acute, destructive bacterial infection of the gingiva characterized by necrosis, ulceration, and spontaneous bleeding of the interdental papillae. Historically known as “trench mouth,” it belongs to the spectrum of necrotizing periodontal diseases and can advance to involve the periodontal ligament and alveolar bone if not treated promptly.

Clinical Presentation

NUG progresses rapidly — often over hours to days — and is distinguished from ordinary gingivitis by the presence of frank tissue necrosis. The hallmark sign is punched-out, crater-like destruction of the interdental papillae covered by a gray-yellow pseudomembrane. Patients typically report a characteristic fetid odor and a metallic taste.

• Severe gingival pain, often spontaneous and out of proportion to visible inflammation
• Necrosis and sloughing of the interdental papillae
• Spontaneous gingival bleeding or bleeding on minimal contact
• Pronounced halitosis and altered taste sensation
• Systemic signs — low-grade fever, malaise, and cervical lymphadenopathy — in severe cases

Causes and Risk Factors

NUG arises from a dysbiotic shift within the subgingival plaque biofilm, with overgrowth of anaerobic organisms — particularly Fusobacterium nucleatum and oral spirochetes of the genus Treponema. Several host and behavioral factors substantially increase susceptibility:

• Psychological stress, which suppresses immune function and alters salivary composition
• Immunosuppression, including HIV infection, where NUG is a recognized indicator condition
• Tobacco use and inadequate oral hygiene
• Malnutrition and chronic sleep deprivation

Diagnosis and Management

Diagnosis is primarily clinical, based on the triad of pain, gingival necrosis, and bleeding. Treatment begins with gentle professional debridement to remove necrotic tissue and disrupt the causative plaque biofilm. Systemic antimicrobials — most commonly metronidazole — are prescribed when constitutional symptoms are present. Oral hygiene instruction, nutritional support, and reduction of modifiable risk factors such as smoking form the cornerstone of long-term management. Without timely intervention, NUG can advance to necrotizing ulcerative periodontitis, causing irreversible attachment loss and destruction of the underlying alveolar bone.

Because NUG responds quickly to appropriate treatment yet readily recurs when precipitating factors go unaddressed, identifying and managing the patient’s systemic and behavioral risk profile is just as important as local gingival care.