Aetiology of recurrent aphthous ulcers (RAU).

A significant decrease in the pH of saliva has been detected in patients with recurrent aphthous ulcers (RAU). The decrease in pH was more prominent at night than between meals, and some persistent decrease was noticed even after recovery. The total proteins of saliva in RAU were also significantly decreased. These findings were similar to those observed in patients complaining of peptic ulcers, so it is recommended that patients with RAU should be treated with antacids as well as anticholinergic drugs, and that the possibility of concomitant peptic ulceration should also be investigated.