Mouth ulcers, frequently referred to as canker sores, are a common oral condition. These small, shallow lesions can emerge on various soft tissues within the mouth, leading to discomfort during speaking, eating, and drinking.
Understanding Mouth Ulcers
A mouth ulcer, also known as an aphthous ulcer or canker sore, is a break or erosion in the mucous membrane lining the oral cavity. These lesions typically appear as small, round or oval sores with a white or yellow center and a distinct red border. They can develop on the inside of the lips, cheeks, tongue, the floor of the mouth, or the soft palate.
Mouth ulcers are distinct from cold sores, which are caused by the herpes simplex virus and usually appear on or around the lips. Unlike cold sores, mouth ulcers are not contagious and are not caused by a viral infection. While both can cause discomfort, their origin and typical locations differ.
Common Causes of Formation
Mouth ulcers can form due to various factors, from physical trauma to systemic influences. Physical injury is a frequent trigger, often resulting from accidental biting of the cheek or tongue, aggressive toothbrushing, or irritation from dental braces or sharp edges of broken fillings. Consuming hard or abrasive foods can scrape the delicate oral tissues.
Nutritional deficiencies can increase susceptibility. A lack of specific micronutrients like iron, vitamin B12, folate (vitamin B9), or zinc can impair mucosal health and regeneration. Stress and hormonal changes are contributing factors, with emotional stress and menstrual cycle fluctuations often correlating with outbreaks.
Dietary elements play a role, as sensitivities to acidic foods such as citrus fruits, tomatoes, or spicy foods can irritate the oral lining. Certain chemical irritants in oral care products, like sodium lauryl sulfate (SLS) in some toothpastes and mouthwashes, can destabilize the mucosal layer. Underlying medical conditions like celiac disease, inflammatory bowel disease, and certain autoimmune disorders can predispose individuals to recurrent mouth ulcers.
The Biological Steps of Ulcer Development
Ulcer development begins with initial damage to the protective oral mucosal lining, often following a trigger or injury. This damage creates a superficial breach in the epithelium, exposing the underlying connective tissue. The body then initiates an inflammatory response, characterized by redness and swelling around the affected area.
Immune cells are recruited to the site, working to clear damaged cells or potential pathogens. This inflammatory cascade can lead to further tissue breakdown and erosion, causing the surface layer of the mucosa to slough off. The erosion deepens, exposing nerve endings within the underlying connective tissue, which accounts for the pain associated with mouth ulcers.
A protective layer then forms over the exposed area, often appearing as a white or yellowish film. This film is primarily composed of fibrin, a protein involved in blood clotting and wound healing, which deposits over the ulcerated surface. The healing process commences, with new epithelial cells migrating from the edges to cover the exposed surface and gradually restore the oral lining.