Ozden H K, Selcuk A A. Is there a role of toothpastes in the development of recurrent aphthous stomatitis? A prospective controlled clinical trial with skin patch testing. Oral Surg Oral Med Oral Pathol Oral Radiol 2020; 10.1016/j.oooo.2020.10.006.

Allergens in toothpastes did not appear to stimulate the formation of RAS.

This study explored whether the skin patch test (SPT) can be used to determine if toothpaste allergens play a role in the aetiology of recurrent aphthous stomatitis (RAS). Sixty-three patients with RAS and 47 healthy volunteers were skin patch tested with sodium lauryl sulfate, cocamidopropyl betaine, propylene glycol, aluminium chloride hexahydrate, menthol, triclosan, and titanium dioxide. Fisher's exact test and the Yates chi-square test were used to compare categorical variables and patch test results between two groups. The SPT was positive in eight (22%) patients with RAS and 11 (23%) control subjects, and the difference between the groups was not statistically significant. Sodium lauryl sulfate, titanium dioxide, and menthol were the most common positive allergens in both groups. Allergens in toothpastes did not appear to stimulate the formation of RAS. To determine a clearer relationship a study in a larger patient series employing intraoral patch testing with more toothpaste ingredients was suggested.