What are the causes of a sore mouth?

Causes of Sore Mouth

A sore mouth results from dental/oral pathology, mucosal diseases, infections, autoimmune conditions, neuropathic disorders, or systemic diseases—with dental causes and oral mucosal lesions being most common. 1

Primary Dental and Oral Causes

Dental pathology represents the majority of acute oral pain and includes:

• Tooth decay, mobile teeth, and gingival inflammation causing localized or difficult-to-localize pain 1
• Excessive wear facets from bruxism contributing to chronic discomfort 1
• Post-dental procedure trauma or complications 1

Oral mucosal diseases present with visible lesions and include:

• Lichen planus causing painful erosive or reticular patterns 1, 2
• Herpes simplex and herpes zoster creating vesicular then ulcerative lesions 1, 2
• Recurrent aphthous ulcers appearing as well-demarcated oval/round ulcers with white/yellow pseudomembrane and erythematous halo 3, 4

Infectious Causes

Fungal infections:

• Oral candidiasis (76.8% caused by C. albicans) presents with oral burning, dysgeusia, and white patches, particularly in immunosuppressed patients or those with dry mouth (OR 3.02) 4
• Deep fungal infections occur especially in patients with hyperglycemia 5

Viral infections:

• Herpes labialis typically presents as self-limited vesicular eruptions 2
• HIV infection can manifest with persistent oral ulcers requiring antibody testing 3, 5

Bacterial infections:

• Syphilis causes palatal ulceration requiring serology 3, 5
• Tuberculosis produces stellate ulcers with undermined edges 3, 5

Autoimmune and Inflammatory Conditions

Bullous diseases require serum antibody testing (Dsg1, Dsg3, BP180, BP230):

• Pemphigus vulgaris and mucous membrane pemphigoid present with painful erosions 3, 6

Systemic inflammatory diseases:

• Behçet's syndrome characterized by recurrent bipolar aphthosis 3
• Inflammatory bowel disease (Crohn's disease, ulcerative colitis) manifesting with oral ulcers 3, 5

Neuropathic Causes

Burning mouth syndrome affects predominantly peri- and post-menopausal women, presenting as:

• Continuous burning of tongue (especially bilateral tip), lips, palate, or buccal mucosa with normal-appearing mucosa 1
• Associated dry mouth, abnormal taste, depression, and poor quality of life 1
• Secondary causes include oral candidiasis, haematological disorders, autoimmune disorders, and medication side-effects 1

Post-traumatic trigeminal neuropathic pain:

• Continuous burning or tingling within 3-6 months of dental trauma or procedures 1
• May present with allodynia or sensory changes 1

Systemic and Hematologic Causes

Blood disorders presenting with widespread necrotic ulcers with yellowish-white pseudomembrane:

• Anemia, leukemia, and neutropenia requiring full blood count and bone marrow evaluation 3, 5

Nutritional deficiencies significantly associated with oral ulceration:

• Vitamin B12 deficiency (OR 3.75) 4
• Folic acid deficiency (OR 7.55) 4
• Iron/ferritin deficiency (OR 2.62) 3, 5, 4

Traumatic and Chemical Causes

Mechanical trauma:

• Sharp food, dental appliances, or iatrogenic injury creating ulcers whose location corresponds to the inciting factor 3, 7

Thermal and chemical injury:

• Hot foods/beverages causing palatal burns 3
• Strong acids, alkalis, or caustic substances 3
• Irritant contact stomatitis from foods, chemicals, metals, spices, or oral care products under exaggerated exposure conditions 7

Other Contributing Factors

Salivary gland disorders:

• Tumors, duct blockage, and infection causing intermittent pain before eating 1
• Salivary stones most frequent in submandibular gland 1

Dry mouth (xerostomia):

• Global prevalence of 23%, associated with using >3 oral medications daily (OR 2.9), head/neck radiation, and Sjögren disease 4
• Increases risk of oral candidiasis by 11.5% 4

Critical Diagnostic Approach

For ulcers persisting >2 weeks or not responding to 1-2 weeks of treatment, obtain:

• Full blood count to detect anemia, leukemia, or blood disorders 3, 5
• HIV antibody and syphilis serology 3, 5
• Fasting blood glucose and coagulation studies 3
• Serum antibodies (Dsg1, Dsg3, BP180, BP230) if bullous disease suspected 3, 5
• Biopsy with direct immunofluorescence for atypical or unclear etiology 3, 5

Common pitfalls to avoid:

• Never rely solely on topical treatments for persistent ulcers without establishing definitive diagnosis, as this delays identification of malignancy or systemic disease 3
• Inadequate biopsy technique (too small or superficial) misses diagnostic features 3, 5
• Overlooking systemic causes leads to delayed diagnosis and inappropriate management 3, 5