The compliance spring is designed for two different applications. Its force is derived from a combination with intermaxillary Class II, Class III, or delta (triangular) elastics. If the elastic hook of the compliance spring is adjusted to protrude slightly into the buccal tissue, it will cause minor soft-tissue irritation that can be alleviated simply by wearing the elastics. The spring auxiliary slides onto the main archwire before the leg of the spring is inserted into the V-slot. The archwire must then be tied into the bracket with a stainless steel ligature to prevent it from becoming dislodged by the spring. When the compliance spring is placed over a round base archwire, it produces single-tooth labial root torque. This is often useful after a palatally impacted canine has been moved into the arch, though the root will still require labial movement. The compliance spring can also provide labial root torque for lingually positioned upper or lower lateral incisor roots. To avoid generating unwanted labial torque, the spring must be used with a rectangular base archwire.