Recurrent aphthous stomatitis may be initiated by traumatic epithelial implantation and sustained by localized pathergic status.

Recurrent aphthous stomatitis (RAS) is the most common oral mucosal disease. The pathogenesis of RAS has been debated long and various etiological predisposing factors have been suggested. Nonetheless, these proposals do not explain development of aphtous ulcerations and the underlying mechanisms remain to be uncovered through more definitive cellular and molecular approaches. Soft tissues of oral cavity are subject to traumatic injuries owing to various functional activities demanding interactions of soft and hard tissues. These injuries may lead to implantation of epithelial cells at the sites of injury. Following implantation of keratinocytes, a mild sustained immunologic reaction to these cells may be expected which is characteristic of aphthous ulcerations. Subsequently, these localized sites of implantation may remain in a pathergic status. Thereafter, these sites exhibit higher vulnerability to recurrence of aphthous ulcerations when affected by environmental stimuli.