Biomechanics of loops in Orthodontics

Biomechanics is study of relationship of mechanical forces acting on biological system. Its application in the field of orthodontics helps to achieve optimum treatment results. For application of biomechanics in orthodontic appliances various biologic and physical variables need to be understood. . Tooth movement is caused not only by the direct application of mechanical forces to teeth and their support structures but application of specific orthodontic force systems is required for optimum control of tooth movement. Factors beyond applied forces are also involved in tooth movement depending on the biological response. The relationships between orthodontic force and tooth movement is precisely defined by the law of statics and dynamics. If we analyse the applied force system, we can accurately predict the nature of motion of a body. If we apply force on a free body, it will move according to the forces acting on it. Since the teeth are not free bodies, but they are surrounded by periodontal structure, forces act in a different way. The forces do not act directly, but they act as a stimulus which must be transduced into biological activity before tooth movement.