Aphthous ulcers, canker sores or RAS (recurrent aphthous stomatitis), occur in 20 – 60% of the population. Although their etiology is unknown, most theories believe that some sort of immune dysfunction comes into play.

The presence of a canker sore can be associated with stress, trauma, nutritional deficiencies, hormonal imbalances and smoking cessation. Many other factors can also contribute to their occurrence.

Aphthous ulcers are more commonly noted in upper socioeconomic groups, professionals and non-smokers.

As for the clinical findings associated with an aphthous ulcer, they present intraorally on movable soft tissues as a small, painful ulcer. Aphthous ulcers typically occur as a single lesion, but a patient can exhibit a few separate lesions at the same time.