Perleche, or angular stomatitis, is most commonly caused by reduced interarch distance, leading to excessive skin folding at the corners of the mouth. This creates a moist, warm environment that favors fungal and bacterial growth, resulting in inflammation and cracking. Reduced interarch distance often occurs due to tooth wear or loss, causing decreased vertical dimension and lip incompetence. Correcting this by restoring proper vertical height helps prevent recurrence. Thus, mechanical factors associated with jaw relationship are key in its etiology.

Reference: Oral Pathology, Neville et al., 4th Edition.