In everyday orthodontic practice it is no longer uncommon for patients to prefer treatment that is as quick and uncomplicated as possible, but above all aesthetic. At least that is the patient's idea. Therefore, the energies of the last few years have increasingly been directed towards the development of transparent splints, so-called "clear aligners" for the treatment of misaligned teeth, which has led to an over saturation of the market in recent years. When researching the internet, 27 different aligner providers were already listed in 2015. However, aligners found their origin years earlier, starting with the idea of correcting minor forms of malocclusion, such as rotated teeth or small crowding of the front teeth. What all splints have in common is that they cover the entire dental arch as a clear, thermoformed plastic splint, but otherwise the models of the various providers can be very different equipped, according to the wishes of the attending dentist. There are still some aligner systems who remain deliberately and explicitly specialized in the treatment of small tooth misalignments and irregularities whilst other aligner systems are able to target complex malocclusions. In order to carry out larger tooth movements, fixed attachments are planned on the buccal shelf of some teeth. Larger and more targeted forces can be applied to the tooth. Studies that show a comparison of aligner systems with fixed appliances were unfortunately often described as inadequate due to a lack of control groups, a lack of blinding or randomization, or poor methodology.