Canker Sore Etiology and Diagnosis

Primary Etiologic Factors

Frequent canker sores result from a multifactorial process involving immune dysregulation, nutritional deficiencies, mechanical trauma, stress, hormonal factors, food sensitivities, and underlying systemic diseases, though the exact cause remains unknown in many cases 1
Iron deficiency can contribute to oral ulceration and should be evaluated 2
Mechanical trauma from sharp food edges, dental appliances, or accidental biting can create ulcers that correspond in location and shape to the inciting factor 3
Trauma sites are particularly vulnerable in individuals predisposed to canker sores 1

Inflammatory bowel disease commonly causes recurrent oral ulceration and requires specific investigation 2, 3
Celiac disease can manifest with oral ulcers, and gluten has been identified as a trigger agent in susceptible individuals 2, 3
Anemia and leukemia can present with oral ulcers, requiring full blood count and potentially bone marrow biopsy 2
Neutropenia may cause widespread necrotic ulcers with yellowish-white pseudomembrane 2
Behçet's disease manifests as recurrent bipolar aphthosis and significantly impacts quality of life 3
Bullous diseases require evaluation for serum-specific antibodies 2
HIV infection can manifest with oral ulcers and should be tested for in persistent cases 2, 3
Syphilis can present with oral ulceration, necessitating serology examination 2, 3
Deep fungal infections occur particularly in immunosuppressed or hyperglycemic patients 2, 3

Smoking status affects disease presentation, with smokers reporting fewer outbreaks 4
NSAIDs can cause oral ulceration as part of gastrointestinal complications 3
Medication review is essential in evaluating recurrent ulcers 3

Any ulcer persisting beyond 2 weeks or not responding to 1-2 weeks of treatment requires specialist referral and comprehensive testing 5, 2, 3
Solitary chronic ulcers >2 weeks must be biopsied to exclude malignancy 3
Full blood count to evaluate for anemia, leukemia, or neutropenia 2, 3
Fasting blood glucose level to assess for hyperglycemia 2, 3
HIV antibody testing in persistent cases 2, 3
Syphilis serology examination 2, 3
Nutritional markers including vitamin B12, folate, and iron levels 3
Coagulation studies before biopsy 5

Relying solely on topical treatments without establishing a definitive diagnosis for persistent ulcers delays identification of malignancy or systemic disease 2, 3
Inadequate biopsy may miss important diagnostic features 2
Overlooking systemic causes leads to delayed diagnosis and inappropriate management 2