Abstract: Studies orthodontic sliding mechanics using preadjusted brackets in the measurement of kinetic frictional forces between a bracket and the archwire, as well as torques and deformed angulations of the bracket. In order to attain precise measurement in the kinetic frictional force tests, special loading apparatus is designed to simulate the slow sliding of orthodontic teeth. Optical methods are developed to measure changes of deformed angulations in bracket wings for the archwire in its torsional state. A rotating wheel is used to exert and measure torques on the bracket. An integrated data acquisition system is designed to collect data automatically. Time graphs of kinetic frictional forces and of torques versus deformations in bracket wings are obtained at real time. These methods provide experimental means to evaluate brackets in clinical medicine, and can similarly be of use to all kinds of engineering measurements for diminutive forces and displacements.