The mechanical motion gives an output in terms of linear, rotatory or oscillatory motion. Special swinging chairs with electrical controls can be used to induce rotatory nystagmus. This dependence of specific rotation on wavelength is called optical rotatory dispersion. The variation of specific rotation with wavelength is called optical rotatory dispersion (ORD). However, the anterior cruciate ligament is the most important contributor to rotatory knee stability. Optical rotatory dispersion can be used to find the absolute configuration of metal complexes. They may be divided into five types&colon; anterior, posterior, lateral, medial, and rotatory. Levamisole, a levo rotatory isomer of imidazothiazole, was previously approved as an antihelminthic and immunomodulator. Other variants with lateral or rotatory displacement have been described, as well as mixed types. It converts the rotatory motion to linear motion, and looks like an animal walking. For single, conical-rooted teeth such as the incisors, rotatory movements are also used. Rotatory or shaky motion of sperms indicates presence of antispermal antibody. Rotatory movements are then made to dislodge the tooth from the socket. In Bangladesh it is five years course followed by a year of compulsory rotatory internship.