This is a functional orthodontic appliance made of a greatly reduced double-plate to which a widened labial bow and a palatally displaced "tongue bar" are attached (Fig 10-81a). It preferentially activates the vestibular musculature (lip closure) and the tongue (correct position and contact with the palate), which is the purpose of the lip bar with two buccinator loops and the tongue bar. It is indicated for shifting and leveling the occlusion and for correcting forms of dysgnathia arising from malfunctioning due to anomalies of the tongue and lip posture.
The labial bow (lip bar) lies at the level of the maxillary anterior teeth, bends down at the canines to the mandible, and is passed along the posterior teeth as a long buccinator loop. It then runs between the canines and premolars over the dentition into the acrylic of the appliance. It is shaped out of 0.9-mm hard steel wire and guided at a small distance from the tooth surfaces.
The tongue bar, like a tightened Coffin spring, runs dorsally over the palate; the 1.2-mm-thick wire is 1 mm away from the mucosa. This is intended to re-educate tongue activity.
The acrylic plate is very slender and mainly comprises a narrow mandibular base. The acrylic reaches the mandibular anterior teeth and, to provide better support for the appliance, is passed up to the occlusal surfaces of the posterior teeth.
The slender basic appliance can be worn all day long without restricting speech and achieves a quick result. It can be used as a distal activator (type 1) (Figs 10-81b and 10-81c).
The shield appliance (type 2) has an acrylic body that runs over the anterior palatal area in the frontal part of the maxilla (Figs 10-81 d and 10-81e). Individual labial or buccal shields can be prepared for the vestibule.The shield appliance is used in an open bite and stops the tongue from sliding between the anterior teeth.
The reverse appliance (type 3) as a prognathism activator relates to the maximum retrusive position (Figs 10-81f and 10-81g). Compared with the basic appliance, its lip bar runs along the mandibular anterior teeth, and the lingual bar loop is bent forward.The lingual plate of the acrylic body runs over the incisal edges of the maxillary anterior teeth and contacts the palatal surfaces of the maxillary posterior teeth.