Aim: To illustrate the importance of treatment timing and the positive effect of applying sound biomechanic principles in a patient with a difficult skeletal pattern. Methods: A female patient, 9 years of age, with a skeletal Class II, Division 1 malocclusion and a long lower face is presented. Mandibular growth was guided in a horizontal direction with a monobloc that reduced the vertical growth potential. The maxillary incisors were intruded 4.5 mm during the second stage of treatment, and the maxilla was widened using rapid
palatal expansion. Full fixed appliances were used and forces were applied to control the vertical dimension. Results: A Class I occlusion was achieved. The patient showed less gingiva when smiling and the vertical dimension was controlled. World J Orthod 2002;3:19–26.