In a few cases, it may be found that spaces are slow or difficult to close with the normal mechanics. If no obstacles to space closure are evident (see below), alternative mechanics may be considered. Tiebac.ks with two modules may help, or a looped archwire can be made. A useful alternative in difficult space-closure situations is the Hycon® device from Edenta. This has been used successfully by one of the authors for 4 years in selected cases.
The device consists of a centimeter segment of 21 x25 rectangular wire, to which is soldered a 7 mm screw device. The rectangular segment is placed in the double or triple tube on the molar, and bent over distally. The screw is provided with a large head, to which a ligature wire can be loosely connected. The ligature wire is then extended forwards and tied to the archwire hook. The developer of the Hycon® device was Dr Winfried Schiitz, a German orthodontist, and he suggests that a small screwdriver be used twice per week to turn the screw one full turn (1/8 mm) in a clockwise direction. Thus, approximately 1 mm of space closure is accomplished per month (Case NH, p. 268). This device provides a very short-acting but strong force that essentially overcomes any frictional concerns. If overdone, however, it will lead to significant archwire deflection, which should be avoided. The I Iycon® device, like palatal expanders, distraction osteogenesis screws, and some molar distalizing devices, requires diligent patient cooperation to ensure success.
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