Acute necrotizing ulcerative gingivitis (ANUG)

Introduction

Acute necrotizing ulcerative gingivitis (ANUG), also known as Vincent's gingivitis or trench mouth, is an acute, rapidly progressive, painful periodontal infection characterized by necrosis and ulceration of the interdental papillae, spontaneous gingival bleeding, and severe halitosis. It represents a severe form of plaque-induced gingival disease in which tissue destruction occurs rapidly due to the synergistic effects of pathogenic anaerobic bacteria and impaired host immunity.

ANUG most commonly affects adolescents and young adults but may occur at any age. It is particularly common among individuals with poor oral hygiene, malnutrition, psychological stress, smoking, diabetes mellitus, HIV infection, and other immunocompromising conditions.

Without prompt treatment, the infection may spread into deeper periodontal tissues, resulting in necrotizing ulcerative periodontitis (NUP). In severely malnourished or immunocompromised children, especially in resource-limited settings, the disease may progress to cancrum oris (noma), a life-threatening gangrenous infection causing extensive destruction of facial soft tissues and bone.

Early recognition and aggressive management are essential to prevent irreversible tissue destruction and systemic complications.

Etiology

ANUG is a polymicrobial infection involving anaerobic bacteria, particularly:

• Fusobacterium species

• Prevotella intermedia

• Treponema species (spirochetes)

• Selenomonas species

• Porphyromonas gingivalis

Disease develops when these microorganisms proliferate in the presence of impaired host defenses.

Predisposing factors include:

• Poor oral hygiene

• Heavy dental plaque accumulation

• Dental calculus

• Smoking and tobacco use

• Malnutrition

• Vitamin deficiencies, especially vitamin C and B-complex vitamins

• HIV infection

• Diabetes mellitus

• Immunosuppression

• Psychological stress

• Sleep deprivation

• Recent acute illness

• Xerostomia

• Previous history of periodontal disease

Risk factors

Individuals at greatest risk include:

• Poor oral hygiene

• Heavy smokers

• HIV infection

• Poorly controlled diabetes mellitus

• Malnourished children

• Immunocompromised patients

• Psychological stress

• Fatigue

• Young adults

• Vitamin deficiencies

• Limited access to dental care

Pathophysiology

ANUG develops through a combination of bacterial infection and impaired immune response.

The sequence of disease includes:

1. Excessive plaque accumulation promotes overgrowth of anaerobic bacteria.

2. Fusiform bacteria and spirochetes invade gingival tissues.

3. Bacterial toxins induce rapid tissue necrosis.

4. Neutrophil dysfunction and impaired host immunity accelerate tissue destruction.

5. Ulceration begins at the interdental papillae.

6. Necrotic tissue becomes covered by a yellowish-white or gray pseudomembrane.

7. Progressive destruction causes severe pain, spontaneous bleeding, and halitosis.

8. In severe untreated cases, infection extends into periodontal tissues or facial structures.

Differential diagnosis

Conditions that should be considered include:

1. Severe plaque-induced gingivitis

2. Acute herpetic gingivostomatitis

3. Necrotizing ulcerative periodontitis

4. Primary oral syphilis

5. Oral ulceration associated with leukemia or agranulocytosis

Signs and symptoms

Patients typically present with sudden onset of symptoms.

Common clinical features include:

• Severe gingival pain

• Painful swollen gums

• Bright red gingiva

• Bleeding gums with minimal provocation

• Spontaneous gingival bleeding

• Necrosis of the interdental papillae

• "Punched-out" interdental papillae

• Yellowish-white or gray pseudomembrane covering ulcers

• Pain during eating and tooth brushing

• Foul-smelling breath (halitosis or fetor ex ore)

• Metallic taste in the mouth

• Excessive salivation

• Difficulty chewing

• Fever

• Malaise

• Cervical or submandibular lymphadenopathy

In advanced disease:

• Extensive gingival destruction

• Periodontal attachment loss

• Bone destruction

• Facial swelling

• Features of cancrum oris (noma), particularly in severely malnourished children

Diagnostic criteria

Diagnosis is primarily clinical.

Characteristic findings include:

• Sudden onset of severe gingival pain

• Necrosis of interdental papillae

• "Punched-out" papillary appearance

• Yellow-gray pseudomembrane

• Spontaneous gingival bleeding

• Severe halitosis

• Gingival erythema

• Heavy plaque accumulation

• Tender regional lymph nodes

• Fever in severe cases

Investigations

Diagnosis is usually clinical.

Investigations may be performed to identify underlying systemic disease or complications.

Dental assessment

• Comprehensive oral examination

• Periodontal examination

• Plaque index assessment

• Periodontal probing after acute inflammation subsides

Imaging

Dental radiographs or orthopantomogram (OPG) if:

• Periodontal involvement is suspected

• Bone destruction is suspected

• Necrotizing ulcerative periodontitis is suspected

Laboratory investigations

Depending on clinical suspicion:

• HIV testing

• Blood glucose testing

• Complete blood count

• Nutritional assessment

• Other investigations for immunosuppressive disorders where indicated

Management

Management aims to:

• Relieve pain

• Eliminate infection

• Remove necrotic tissue

• Restore oral hygiene

• Prevent disease progression

• Identify and treat underlying systemic conditions

Treatment is usually performed in stages because severe pain often limits immediate comprehensive periodontal therapy.

Non-pharmacological management

Initial professional care

• Gentle removal of superficial plaque and necrotic debris

• Professional cleaning using 3% hydrogen peroxide under local anesthesia where necessary

• Irrigation of affected areas

• Careful debridement of necrotic tissue

• Removal of local plaque-retentive factors

Oral hygiene instruction

Patients should be advised to:

• Brush teeth gently with a soft toothbrush

• Maintain meticulous oral hygiene

• Rinse with warm saline several times daily

• Resume normal tooth brushing as pain improves

• Clean the tongue daily

• Replace toothbrush after recovery

Lifestyle modification

• Stop smoking immediately

• Improve nutritional intake

• Increase fluid intake

• Ensure adequate rest

• Control diabetes

• Seek HIV care where appropriate

Pharmacological management

Analgesics

• A: Paracetamol (PO) 1 g every 8 hours for at least 3 days,

• OR A: ibuprofen (PO) 400 mg every 8 hours for at least 3 days,

• OR C: diclofenac (PO) 50 mg every 8 hours for at least 3 days.

Antiseptic mouthwash

• A: Hydrogen peroxide 3% mouthwash every 6 hours for at least 7 days,

• OR A: povidone iodine 0.5% mouthwash every 8 hours for at least 7 days,

• OR B: chlorhexidine gluconate 0.1% mouthwash every 12 hours for at least 5 days.

Topical oral gel

• C: Lidocaine + chlorhexidine gluconate + metronidazole oral gel every 8 hours for at least 7 days.

Systemic antibiotic

• A: Amoxicillin (PO) 500 mg every 8 hours for at least 7 days,

• OR A: erythromycin (PO) 500 mg every 8 hours for at least 7 days (penicillin allergy),

• AND A: metronidazole (PO) 400 mg every 8 hours for at least 7 days.

Referral

Refer urgently to a dental surgeon, periodontist, or oral and maxillofacial surgeon if:

• There is extensive tissue necrosis

• Necrotizing ulcerative periodontitis is suspected

• Facial cellulitis develops

• Cancrum oris (noma) is suspected

• Severe immunosuppression is present

• Symptoms fail to improve within 48–72 hours

• Airway compromise or inability to eat develops

Complications

Untreated ANUG may result in:

• Necrotizing ulcerative periodontitis

• Progressive periodontal attachment loss

• Alveolar bone destruction

• Gingival recession

• Tooth mobility

• Tooth loss

• Periodontal abscess

• Facial cellulitis

• Cancrum oris (noma)

• Sepsis in severely immunocompromised patients

• Malnutrition due to painful eating

Prevention

Preventive measures include:

• Brush teeth at least twice daily with fluoridated toothpaste.

• Clean between teeth daily using dental floss or interdental brushes.

• Attend regular dental examinations and professional cleaning.

• Stop smoking and avoid tobacco products.

• Maintain adequate nutrition.

• Correct vitamin deficiencies.

• Ensure good glycaemic control in patients with diabetes.

• Maintain effective HIV treatment where applicable.

• Seek early treatment for bleeding or painful gums.

Patient education

Patients should understand that:

• ANUG is an acute bacterial infection requiring prompt treatment.

• Delaying treatment may lead to permanent damage to the gums and supporting tissues.

• Antibiotics should always be completed as prescribed.

• Good oral hygiene remains essential during recovery, although brushing may initially be uncomfortable.

• Smoking significantly delays healing and increases recurrence.

• Good nutrition supports immune function and healing.

• Persistent or recurrent ANUG should prompt evaluation for underlying conditions such as HIV infection or diabetes mellitus.

Prognosis

With prompt professional debridement, appropriate antibiotics, effective pain control, and improved oral hygiene, most patients experience significant clinical improvement within 24–72 hours, with complete healing occurring over 1–3 weeks.

Failure to address predisposing factors such as poor oral hygiene, smoking, malnutrition, or uncontrolled systemic disease increases the risk of recurrence and progression to necrotizing ulcerative periodontitis or, in vulnerable children, cancrum oris.