Background: Oral mucosa is exposed to a large number of antigenic agents contained in toothpastes. These agents are reported to stimulate recurrent aphthous stomatitis (RAS) pathogenesis, and toothpastes that do not contain probable allergenic substances reduced the number and frequency of aphtous ulcers.

Objectives: We aimed to determine whether the skin patch test (SPT) can be used to determine toothpaste allergens playing role in the etiology of RAS.

Methods: Sixty-three patients with RAS and 47 healthy volunteers were skin patch-tested with; sodium lauryl sulfate, cocamidopropyl betaine, propylene glycol, aluminum chloride hexahydrate, menthol, triclosan and titanium dioxide, which are present in most of the toothpastes. The blotting paper was impregnated with the hapten with the help a plastic syringe, and they were adhered to the backs of the participants using a hypoallergenic, water-tight plaster. The second author evaluated the SPT results at the hours of 48, 72 and 96 after removal of the skin patches. Statistical significance was set at p <0.05.

Results: The skin patch test was positive in 8 (22.2%) RAS patients and 11 (23.4%) controls and the difference between the groups was not statistically significant (p > 0.05). When aphtous ulcer frequency was grouped as 3-6 and more than 6 per year, no difference was found between the two groups in terms of patch test results (p > 0.05). Sodium lauryl sulfate, titanium dioxide and menthol were the most common positive allergens in both groups. An irritant reaction was not detected in any of the participants.

Conclusions: Allergens in toothpastes did not appear to stimulate the formation of RAS. However, in order to determine a clearer relationship, a study on a larger patient series, employing intraoral patch testing with more toothpaste ingredients may be conducted.