Recurrent oral aphthous ulcer is the most common oral lesion in occurrence and one of cause is oxidative stress so investigators need to use antioxidant drugs like topical coenzyme Q10 gel to treat the lesion and more safe for the participants.

Double randomized clinical trial study using two parallel group suffer from oral aphthous ulcer one take antioxidant topical q10gel and other group take placebo carpabol gel two times per day for seven days measuring outcome at fourth and seventh day including pain; healing period and clinical parameters.

Sample size of study include 26 in each group.

Inclusion Criteria:

• Patients with free medical history and no systemic diseases16.
• Patients clinically diagnosed as suffering from symptomatic oral minor aphthous ulcers.
• Patients who agreed to take medications.

Exclusion Criteria:

• Patients suffering from any systemic disease as Crohn's disease, Behcet's disease and others.
• Anemic and leukemic patients (using complete blood count investigation)
• Patients taking systemic drugs such as systemic steroids and other immunosuppressive therapy.
• Patients treated with any oral topical medications 48h before the study27.
• Pregnant and lactating mothers.

double blind