The craniofacial structure changes with time: it is not just made up of bones and muscles, as other parts of the body, but it also includes teeth which affect its structural development. Two variables play a role during growth: genetics and function. The morphofunctional balance is given by the combination of these factors. With regard to genetics, science there is still much to learn. An altered function can be modified. Therefore myofunctional therapy is an efficient support for orthodontics, because altered functional conditions can cause irreversible anomalies to the facial morphology.