The purpose of this study is to evaluate the efficacy and safety of BNP105 in the treatment of recurrent aphthous stomatitis.

Inclusion Criteria:

• Ability to confirm voluntary participation and agree to all trial purposes by signing and dating the informed consent forms;
• Age greater than or equal to 12 years;
• One minor recurrent aphthous stomatitis with onset of symptoms within 48 hours;
• Moderate to severe baseline pain, with VAS ≥ 60 mm (EVA scale 0-100 mm).

Exclusion Criteria:

• Any clinical findings that, in the judgment of the investigator, may interfere with the safety of research participants;
• Participants diagnosed with: Behcet's disease, rheumatoid arthritis, systemic lupus erythematosus, reactive arthritis, Reiter's syndrome, Crohn's disease, ulcerative colitis);
• Participants with diseases that affect healing (e.g. diabetes);
• Immunocompromised participants;
• Participants with aphthous herpetiform ulceration or major aphthous ulceration;
• Participants using medication to treat oral ulcerations (systemic or local);
• Participants who used analgesics or anti-inflammatory drugs in the 6 hours prior to the beginning of the study;
• Participants who used systemic antibiotics in the 2 weeks prior to the beginning of the study;
• Participants using medications that can confuse pain assessment (psychotropics, antidepressants and sedative-hypnotics), except when on a stable dose for at least 30 days prior to the screening visit, and the dose cannot be changed during the clinical trial;
• Participants with current smoking habits.
• Participants who are pregnant, breastfeeding or planning to get pregnant or female participants with the potential to become pregnant who are not using a reliable method of contraception;
• Known hypersensitivity to the formula components used during the clinical trial;
• Participants with current or medical history of cancer in the last 5 years;
• Participants who participated in other research protocol in the last 12 months, unless the investigator judges that there may be a direct benefit to it.