[How effective is asymmetrical headgear in practical use?]

The asymmetrical face bow with internal hinge was successfully employed in the treatment of all examined patients. It finds application as an individual appliance, in combination with removable appliances, and in conjunction with the fixed appliance technique. The major advantage of the face bow is that during a check-up visit, because it is already in place, it presents itself as a proven means for the treatment of asymmetries by adding a hinge on the side not to be distalized and by shortening the external arm on the same side. It is not necessary to employ a new, special face bow or even to change the orthodontic bands. In addition, in the case of an intermaxillary midline correction, no anchorage loss occurs. In the case of more extensive molar rotations, a pretreatment with a palatal archwire is recommended to rotate the molars. Because in 4% of the patients a cross bite or a cross bite tendency arises on the side distally treated, at the beginning of treatment the use of bands with attachments for palatal archwires should be considered. Relatively sizable distal forces in the range of 2:1 to 4:1 are exerted on the molar. This should be taken into account when selecting the forces of the external arm. It is recommended to apply on each of both sides a distal force of no more than 4 to 5 N. Decoupling of forces and movements through the internal hinge makes it possible for the practitioners to check the asymmetrical effect of the face bow by pulling out carefully the lingual archwire from the right or left tube. As long as the hinge still folds down, when the face bow is applied, the geometrics of the face bow should be altered. The following procedures can be recommended: 1. Further shortening of the already shortened arm; 2. outward bending of the long external arm; 3. use of an additional stop tube at the lingual archwire on the side that must be distalized. During the use of related low-pulls, the molars are subjected to diverse forces as a result of preferred sleeping positions, head bearings, and extensive friction, To avoid these non-calculable asymmetries, it is recommended to use gliding low-pulls. Because of the excellent results achieved throughout the use of the asymmetrical headgear with the lingual archwire, it can be recommended that it become a standard appliance in clinical practice.