What causes aphthous ulcers?

Causes of Aphthous Ulcers

Aphthous ulcers (canker sores) are primarily caused by an abnormal immune response triggered by multiple factors including genetic predisposition, local trauma, nutritional deficiencies, and systemic conditions. 1

Primary Causes and Triggers

Immune System Dysfunction

• Genetically mediated disturbances in both innate and acquired immunity play a central role in aphthous ulcer development 2
• The earliest visible lesions typically develop over lymphoid follicles 3
• Characterized by focal inflammation and an abnormal immune response to oral mucosal tissue

Common Triggers

1. Physical Trauma

   • Local physical trauma to oral mucosa 4
   • Ill-fitting dental appliances 1
   • Sharp tooth edges 1

2. Dietary Factors

   • Hard, acidic, spicy, or salty foods 1, 5
   • Toothpastes containing sodium lauryl sulfate 1, 5
   • Alcohol and carbonated drinks 1, 5

3. Nutritional Deficiencies

   • Vitamin B complex (B1, B2, B6) deficiencies 6
   • Iron deficiency 1
   • Folate deficiency 7

4. Systemic Conditions

   • Gastrointestinal disorders:
     • Celiac disease 7, 2
     • Inflammatory bowel diseases (Crohn's disease, ulcerative colitis) 7, 2
   • Immune disorders:
     • HIV infection 1
     • Neutropenia 7
     • Behçet's disease (characterized by recurrent bipolar aphthosis) 7

5. Other Contributing Factors

   • Stress 2
   • Hormonal changes 2
   • Certain viral and bacterial infections 2
   • Elevated blood glucose (predisposes to fungal infections that may present as oral ulcers) 3, 1

Diagnostic Considerations

When to Suspect Underlying Conditions

• Ulcers persisting beyond 2 weeks 1
• Multiple recurrent episodes (4+ times per year) 7
• Unusual patterns or locations of ulceration
• Systemic symptoms accompanying oral ulcers

Important Diagnostic Tests

• Complete blood count to evaluate for anemia, leukemia, or other blood disorders 1
• Fasting blood glucose to check for diabetes 3, 1
• HIV antibody test and syphilis serology for suspected infections 3, 1
• Biopsy for persistent ulcers (>2 weeks) to rule out malignancy 1

Prevention Strategies

• Avoid known triggers (hard, acidic, spicy foods; SLS-containing toothpastes) 1, 5
• Maintain good oral hygiene with soft toothbrush and mild non-foaming toothpaste 1
• Consider vitamin B complex supplementation if deficient 6
• Manage stress through appropriate techniques 2
• Address any underlying systemic conditions 7, 2

Clinical Pearls

• Most aphthous ulcers are minor (less than 10mm) and heal within 7-10 days without scarring 4
• Approximately 10% of cases involve major aphthous ulcers (>10mm) that can cause scarring 4
• Any oral ulcer persisting beyond 2 weeks requires further investigation to rule out malignancy 1
• Recurrent aphthous stomatitis (RAS) is defined by recurrence of oral aphthous ulcers at least 4 times per year 7