What causes aphthous ulcers?

Causes of Aphthous Ulcers

Aphthous ulcers (canker sores) are primarily caused by a combination of genetic predisposition, immune system dysfunction, and various triggering factors including stress, trauma, nutritional deficiencies, and food sensitivities. 1, 2

Types of Aphthous Ulcers

• Minor aphthous ulcers: Most common form, small lesions (<1 cm) that heal within 7-14 days
• Major aphthous ulcers: Larger (>1 cm), deeper, more painful, and may take weeks to months to heal
• Herpetiform aphthous ulcers: Multiple small clustered ulcers that may coalesce 3

Primary Causative Factors

Genetic Factors

• Family history is a significant risk factor
• Genetic predisposition affects approximately 20% of the general population 2

Immune System Dysfunction

• Abnormal immune response in the oral mucosa
• T-cell mediated immune response against oral epithelium
• Increased oxidative stress with higher levels of malondialdehyde (MDA) and lower antioxidant vitamins 4

Common Triggers

Local Factors

• Trauma: Injury from sharp foods, dental appliances, toothbrush injury, or accidental biting 1
• Oral hygiene products: Toothpastes containing sodium lauryl sulfate 1

Systemic Factors

• Nutritional deficiencies:

  • Vitamin B12 deficiency 5
  • Iron deficiency
  • Folate deficiency
  • Zinc deficiency
  • Decreased levels of antioxidant vitamins (A, C, E) 4

• Stress and psychological factors: Emotional stress can trigger or worsen outbreaks 2, 3

• Hormonal changes: Menstrual cycle fluctuations 2

• Food sensitivities: Reactions to certain foods including:

  • Acidic foods (citrus fruits, tomatoes)
  • Spicy foods
  • Nuts
  • Chocolate
  • Certain preservatives 1

Associated Systemic Conditions

Aphthous-like ulcers can be associated with underlying systemic conditions:

• Gastrointestinal disorders:

  • Celiac disease
  • Inflammatory bowel disease (Crohn's disease, ulcerative colitis) 3

• Immunological disorders:

  • Behçet's disease (characterized by recurrent bipolar aphthosis)
  • HIV infection
  • Neutropenia 3

• PFAPA syndrome (Periodic Fever, Aphthous stomatitis, Pharyngitis, Adenitis) 6

Diagnostic Approach

When aphthous ulcers persist beyond 2 weeks or are recurrent:

1. Evaluate ulcer characteristics (duration, shape, location, number, appearance)
2. Consider blood tests to rule out nutritional deficiencies (B12, folate, iron, zinc)
3. Consider biopsy if ulcers are persistent, unusual in appearance, or don't respond to treatment 7, 1

Prevention Strategies

• Maintain good oral hygiene with soft toothbrush and mild non-foaming toothpaste
• Avoid known trigger foods
• Address nutritional deficiencies
• Manage stress effectively
• Avoid oral trauma 1

Remember that while aphthous ulcers are painful and bothersome, they are generally benign and self-limiting. However, persistent ulcers (>2 weeks) should be evaluated to rule out more serious conditions including oral cancer.