[The loss of force by friction in arch-guided tooth movement].

Employing arch-guided tooth movement always results in a loss of force by friction. In order to quantify the loss of force, an apparatus was designed featuring a simulated tooth with full three dimensional mobility. Five different wire alloys in five wire dimensions were combined with three brackets of different widths. Under optimal circumstances the ratio of applied force to orthodontically effective force was 2.3. In respect to the wire dimension the generated friction primarily depends on the vertical diameter. Wide brackets generate less friction than narrow ones. There are significant differences between the examined wire alloys. To minimize friction, a low surface roughness is of high importance.