Andrea Wichelhaus

Applied biomechanics

Independently of the selected prescription of the bracket system used, sliding mechanics does not lead to the desired individual treatment results of complex patients. Orthodontic therapy is eased by individually adapted biomechanics and a modified sliding mechanics with targeted forces and moments. Prefabricated materials allow the targeted and defined application of moments. This enables the clinician to select a moment depending on movement, tipping, controlled tipping and bodily movement. NiTi segmented archwires and compound materials may be a useful supplement to conventional orthodontic therapy. Biomechanically, not only moments and forces are more manageable through the modified sliding mechanics but also side effects. Additionally, anchorage control is facilitated. Patients with difficult movements and large movement distances and patients requiring interdisciplinary treatment can not only be treated successfully, but also with a highly functional and aesthetic result.

Innovations in straight-wire therapy

Straight-wire mechanics, developed by Andrews in the 1970s, are based on the anatomical conditions of the teeth. The integration of first, second and third order bends into the bracket system has significantly facilitated the orthodontic therapy and made sliding mechanics possible. A dynamisation of the straight wire therapy was striven for by applying different prescriptions and slot dimensions. Clinical investigations show that this is only possible to a quite limited extent. Besides active movements along the arch, deficits of the straight wire technique manifest also in the finishing phase in the poor transmission of corresponding torque. In recent years, the individualization of the straight wire technique has been further developed when applying digitalization and indirect bonding. Studies show, however, only a short reduction of the treatment duration and no improvement of the clinical result. Reasons for this are the limited predictability of the biological reaction, the slot geometry (rectangular slot), manufacturer´s tolerances and the use of a mechanically rigid bracket system. A dynamisation of the orthodontic therapy was achieved by a newly developed bracket system made from Nickel-Titanium alloy in combination with a new slot geometry. The so-called “V-slot mechanics”, in combination with a superelastic alloy, allow the transmission of dynamic and small moments. Thus, the V-slot mechanics represent an entirely new treatment approach in orthodontics, leading to a “biologisation” of the treatment together with a biomechanical individualisation.