The prediction of distortion in formed orthodontic appliances

The theoretical prediction of the onset of distortion within a retraction U-loop as derived from a knowledge of the maximum bending moment, the wire characteristics and the loop dimensions was found to be in good agreement with the experimental measurements carried out on large scale models of the U-loops. The ability to predict distortion in appliances should be of use in any comparison of the properties of the different designs of U-loop or in the evaluation of different designs of orthodontic appliance.