The purpose of this study is to evaluate the therapeutic clinical efficacy of a synthesized 5 wt.% chitosan nanoparticle paste compared to a standard topical corticosteroid (triamcinolone acetonide 0.1% oral paste) in patients suffering from minor recurrent aphthous stomatitis. The study specifically monitors changes in clinical ulcer diameter and pain reduction.

Recurrent aphthous stomatitis (RAS) is a common oral mucosal disease causing significant pain and discomfort. This randomized, active-controlled, single-blind clinical trial investigates a novel mucoadhesive 5 wt.% chitosan nanoparticle paste formulation synthesized via the ionic gelation technique. Eligible patients diagnosed with minor RAS are randomly allocated in a 1:1 ratio to either Group A (active control: triamcinolone acetonide 0.1% oral paste) or Group B (experimental: 5 wt.% chitosan nanoparticle paste). Both groups apply their designated medication topically four times a day using a sterile swab after rinsing and drying the affected area. Treatment is continued until complete healing of the ulcer occurs. Clinical follow-up examinations are performed periodically at days 0, 1, 6, and 10 to measure the clinical ulcer diameter using a Hu-Friedy periodontal probe and to record subjective pain scores via a Visual Analogue Scale (VAS).

Inclusion Criteria:

• Patients complaining of oral recurrent ulcers with signs of minor recurrent aphthous stomatitis.
• History of oral recurrent ulcers with a recurrence rate of 2 to 3 times per year.
• Ulcer diameter less than 1 cm at baseline.
• Maximum of 4 days passed since the emergence of the current ulcer.
• No use of any prior medications or treatment for the current ulcer.
• Signed written informed consent.

Exclusion Criteria:

• Background of systemic diseases, including diabetes mellitus.
• Connective tissue diseases such as Lupus.
• Syndromes or diseases related to aphthous ulcers, such as cyclic neutropenia and Behcet's disease.

To ensure rigorous single-blinding, medications were dispensed in masked, identical containers by an independent coordinator. The clinical investigator performing all follow-up measurements and scoring was completely blinded to the treatment assignments.