The Forsus Fatigue Resistant Device (FRD) is a hybrid functional appliance used for treatment of Class II and Class II subdivision malocclusion and for midline corrections. To ensure a symmetrical installation on the left and right sides when using the L-pin attachments (as opposed to the EZ modules), we recommend the following procedure:
1. Mark the leg of one of the L-pins provided with the Forsus kit at a point 2mm away from the L-bend, measuring with a vernier or other precision caliper (A). This space provides an adequate amount of play for the spring after activation.
2. Insert the marked pin into the headgear tube of a spare prewelded molar bracket, so that the mark lies immediately distal to the tube. Make a second mark on the pin just mesial to the molar tube (B).
3. Remove the pin from the tube and transfer the same markings to the second pin (C). The mesial marks on the right and left sides will be visible during installation of the Forsus, so the pins can be bent precisely and symmetrically at these marks.
We find that taking a few extra steps makes insertion of the Forsus appliance with L-pins much easier. Later reactivation using the manufacturer's crimpable stops will also be more precise if these steps are followed.