Rapid maxillary expansion with incisor intrusion: a study of vertical control

This is a prospective study of 20 consecutively treated patients needing maxillary expansion and incisor intrusion. The patients were treated with a bonded maxillary expansion appliance, intrusion of the incisors with either a one-piece or three-piece base arch and anchorage augmented by the use of vertical-pull chincup therapy. Because rapid palatal expansion and intrusion of maxillary incisors both produce extrusion of posterior teeth, this study was undertaken to determine if a combination of controlled forces could prevent undesirable increases in vertical dimension. The maxillae were widened approximately 8 mm, the incisors were intruded 3 mm, the maxillary molars stayed the same or were intruded slightly, and the mandibular plane angle stayed essentially the same. In addition, A-point was retracted slightly and the occlusal plane was rotated in a counter-clockwise direction.