Objectives: oral lesions, sometimes caused by removable and fixed orthodontic devices, represent an unpleasant trouble that can reduce patient cooperation. Aim of this in vivo study was to test the efficacy of a 5,16% peroxyde hydrogen and 0,1% hyaluronic acid mouthwash in reducing pain and healing time of this kind of traumatic lesions. Methods: a sample of 18 patients, with orthodontic device derived oral lesions, was randomly splitted in a group A, treated with the hydrogen peroxide and hyaluronic acid mouthwash, and in a group B, treated with a placebo mouthrinse. After traumatic factor removal, every patient daily registered on a VAS scale for 1 week his pain intensity and was evaluated by a third operator that registered lesion healing speed and the presence of discolorations or side-effects. One month after lesions healing the groups were crossed and, when new lesions appeared, the study continued following a cross over design. Results: there was no patients showing side effects or teeth discoloration. Test group A had a mean VAS value 1.34 points lower and an healing process 1.74 days on average faster than control group B. Conclusions: even if we tested a small group of patients, it seems that this mouthwash is effective on pain reduction and healing fastening of orthodontic derived oral lesions, after the traumatic agent removal. Absence of side effects facilitate patience adherence to the mouthrinse protocol.