Etiology and Clinical Management of Recurrent Aphthous Ulcers (Canker Sores)

Multifactorial Etiology

• Recurrent aphthous ulcers arise from a combination of disturbed immune response, genetic predisposition, nutrient deficiencies, oral trauma, and stress; no single factor has been definitively proven as the sole cause. 1
• The condition is considered multifactorial, with variable contributions from different mechanisms in individual patients. [1][3]

Local Mechanical and Chemical Factors

• Mechanical trauma—such as sharp tooth edges, dental procedures, or accidental biting—can trigger ulcer formation. [2][1]
• Physical injury, including thermal burns to the oral mucosa, is a recognized precipitating factor. 1
• Chemical irritation from strong acids or alkalis may initiate lesions. 1

Immunologic and Nutritional Factors

• A disturbed immune response, likely mediated by genetic alterations affecting both innate and adaptive immunity, is the leading suspected mechanism. 3
• Deficiencies of vitamins, particularly vitamin B12 and folate, are associated with increased risk of aphthous ulcers. 3

Systemic Disease Associations

• Canker sores may be secondary manifestations of systemic conditions, including inflammatory bowel disease (Crohn’s disease, ulcerative colitis), autoimmune disorders, and certain skin diseases. 1
• Psychological stress and anxiety are linked to the occurrence of recurrent aphthous ulcers. 1

Clinical Evaluation and Management

• A thorough history and comprehensive systems examination are essential to differentiate idiopathic ulcers from those secondary to systemic disease, as the latter can herald serious conditions such as malignancy, autoimmune disease, or inflammatory bowel disease. [2][1]
• Ulcers that persist longer than 2 weeks or fail to improve after 1–2 weeks of standard therapy should prompt biopsy and systemic work‑up to exclude underlying pathology. [2][3]