The cooperation of an orthodontist and a dental hygienist is dealt with, the benefits of such cooperation and the role of a dental hygienist in the improvement of oral hygiene in patients undergoing orthodontic tretment is discussed. The sample included 60 healthy patients treated with appliance in both arches. 50% of the patients attended an orthodontic practice wich closely cooperates with a dental hygienist, the rest of patients attended the practice where the cleaning teeth technique is explained only once, after the adjustment of the fixed appliance.