This is a prospective, randomized, blinded, placebo-controlled, crossover clinical trial to evaluate the efficacy of 2-DeNT oral topical powder in the treatment of recurrent aphthous stomatitis (RAS). To be included in the study, subjects must have had minor RAS ulcers of less than 48 hours duration. It was randomly determined which powder was used first; all subjects used both the 2-DeNT powder and the placebo powder. Subjects applied the powder twice daily and maintained a daily log recording the size of the ulcer, its erythema score, and their level of pain. The subjects continued applying the 2-DeNT powder until the ulcer was resolved.

Inclusion Criteria:

• a history of minor recurrent aphthous stomatitis (RAS) lesions occurring at least 3-4 time/ year, and usually requiring 5 or more days to resolve
• presence of an active ulcer of less than 48 hours duration on either the buccal or labial mucosa (making them more easily accessible for powder application)
• willing and able to give informed consent

Exclusion Criteria:

• pregnant or lactating
• if ulcers were manifestations of a systemic disease process such as ulcerative colitis, Crohn's disease, Behcet's syndrome, or anemia;
• concurrent clinical conditions that could either pose a health risk to the patient by being involved in the study or potentially influence the outcome of the study
• hypersensitivity to dexamethasone, diphenhydramine, tetracycline, metronidazole, nystatin, karaya gum, or zinc oxide
• having used corticosteroids, oral retinoids, or other immunomodulatory agents within one month of participation in the study; non-steroidal anti-inflammatory agents (e.g., aspirin, ibuprofen, etc.), acetaminophen, or oral antihistamines chronically within one month of participation in the study or any use within five days of participation in the study; topical medication (including steroids, retinoids, and anti-microbial drugs) within two weeks of participation in the study, systemic antibiotics within two weeks of participation in the study; any preparation or medication (OTC or prescription) applied to the ulcer within 48 hours of participation in the study
• history of drug or alcohol abuse
• having had any dental work within 2 weeks of study entry
• having had any orthodontic or oral appliances (that could cause oral trauma) within 1 cm of the ulcer or any recollection of trauma in the area of the ulcer
• participating in any other study involving investigational or marketed products within 1 month of study entry or plans to participate in such an investigation during this study.